On a late spring morning along Surf City, the first movement is often above the water, not within it. Brown pelicans travel low and steady just beyond the breakers, their wingtips nearly touching the surface as they follow a line that seems invisible from shore. Farther out, a group of terns holds in place against the wind, hovering, adjusting, then dropping sharply into the water before rising again. Closer to the sound side of Topsail Island, an osprey circles once, then folds into a dive toward a channel edge that looks, at first glance, no different than the water around it.
Nothing about these movements is random. They are responses to structure that exists beneath the surface—structure shaped by tide, wind, and the movement of other organisms. What appears as scattered bird activity is, in practice, a map of where the water is concentrating life.
For someone standing at the edge of it, that movement is one of the most accessible ways to read what cannot be seen directly.
What Birds Are Following Beneath the Surface
The birds that move along this stretch of coast are not searching broadly; they are tracking concentration. Along barrier island systems like those in Onslow County, physical processes—tidal exchange through inlets, wind-driven surface currents, and subtle differences in bottom shape—create zones where small fish, shrimp, and other prey accumulate (Peterson & Peterson, 1979; Piersma, 1997).
When the tide moves through places like New River Inlet, water does not flow evenly across the landscape. It accelerates through constrictions, slows along marsh edges, and bends around sandbars and channels. These shifts in speed and direction compress organisms into tighter spaces, particularly along boundaries where moving water meets something that resists it—an edge, a drop-off, or a change in depth (Wright et al., 1985).
Small schooling fish respond to that compression by tightening their formation. In doing so, they become more visible and more vulnerable. Larger fish—bluefish, Spanish mackerel, and juvenile coastal sharks—often move in from below, using that same concentration to feed. The pressure from below pushes prey upward, sometimes all the way to the surface.
Coastal birds feeding where prey has been concentrated near the surface along the breakers. | Image credit: A. Mitchell
What appears overhead depends on which part of that concentration each species is built to exploit.
Terns hovering and diving are often responding to prey that has been driven upward by predatory fish (Safina & Burger, 1985). Brown pelicans, which rely on plunge-diving, tend to follow more stable schools of fish that remain near the surface for longer periods (Shields, 2014). Ospreys, in contrast, depend on clear water and individual fish they can visually isolate, which is why their activity often aligns with calmer conditions and defined channel edges (Poole et al., 2002).
Each species is not simply feeding in the same place; each is reading a different layer of the same system.
When Surface Activity Signals Pressure Below
From the shoreline, bird activity can appear as isolated events—one dive, then another, then a sudden shift down the beach. Watched over time, a pattern emerges. A cluster of terns may concentrate in one location for several minutes, then disperse abruptly, reforming farther along the shoreline. Pelicans may align along a narrow band just beyond the breakers, following it as it drifts.
These shifts often reflect changes in how prey is being compressed and released beneath the surface. When predatory fish move through a bait school, the school tightens, rises, and becomes briefly accessible from above. When that pressure dissipates, the school spreads out again, and the birds move on.
This movement of energy—from smaller organisms to larger predators, and upward through the water column—is one visible expression of a trophic cascade. The term itself is often used to describe longer chains of ecological influence, but along the coast it can be observed in compressed moments, where the effects of predation become visible within seconds (Heithaus et al., 2008).
Birds do not initiate this process. They respond to it. Their presence marks where the system has already intensified.
Indicator Species at the Water’s Edge
From the beach, the difference is subtle. The water does not change color dramatically, and the waves continue to break as they did before. The level of activity shifts within that band—first visible in the air, then inferred below– marking places where the system has tightened, energy is moving through multiple layers at once, and the distance between surface and depth has, for a time, narrowed (Heithaus et al., 2008; Estes et al., 2011).
For someone entering the water, these differences in bird behavior can offer practical information, not in a predictive or absolute sense, but as indicators of what is happening just below the surface.
Brown pelicans traveling low in a consistent line often indicate schools of fish moving parallel to shore. Terns repeatedly diving in a tight area suggest smaller prey being pushed upward, frequently by larger fish feeding below. Ospreys focusing on a specific channel edge reflect clearer water and individual prey availability, rather than broad schooling events. Along the shoreline, shorebirds probing the sand at low tide are responding to invertebrates exposed by receding water, signaling a different layer of the system entirely—one tied to sediment and tidal timing rather than active predation (Colwell, 2010; Piersma, 1997).
None of these signals point directly to a specific species beneath the surface. What they indicate is concentration, and concentration is what draws larger predators closer to shore.
Along the coast of North Carolina, nearshore and juvenile shark presence is often associated with areas of high prey density, particularly where schooling fish aggregate (Heupel & Hueter, 2002). These conditions are not constant, and they shift with tide, temperature, and time of day. Birds make those shifts visible in real time.
At times, that activity stretches into lines that run the length of the breakers.
For someone stepping into the water, that narrowing matters. Not as a warning in the abstract, but as a recognition that the conditions supporting visible feeding above often extend below, linking organisms that are rarely seen together into the same moving structure.
Where the System Tightens
The patterns become easier to see near places where the water is forced to narrow, turn, or accelerate. The most consistent bird activity along this coast tends to occur where water movement is constrained and redirected. Inlets, marsh edges, sandbars, and the transitions between the Intracoastal Waterway and adjacent sounds create these zones (Wright et al., 1985).
At New River and its inlet, tidal flow compresses water into narrow channels before releasing it into broader areas, creating gradients in speed and depth. Along these gradients, prey accumulates, predators follow, and birds gather above.
These are not fixed points. As tide rises and falls, and as wind reshapes surface conditions, the locations of these compression zones shift. The birds move with them, tracing patterns that are constantly changing but not random.
For someone watching from shore, these movements can be read as lines, clusters, and absences—places where activity intensifies, and places where it suddenly drops away.
Standing Within It
Entering the water along this coast means stepping into a system already in motion. The surface may appear uniform, but the activity above it often reveals where that motion is focused.
Birds diving repeatedly in a confined area, or tracking a narrow band just beyond the breakers, indicate where prey is concentrated. Those same conditions are what draw larger predators into closer proximity to shore, not as an anomaly, but as part of the same process.
Watching the birds does not eliminate risk, and it does not provide certainty about what is beneath the surface. What it offers is context—a way to recognize when the water is more active, more compressed, and more connected across its layers.
What appears as feeding from above is part of a larger structure moving through the water. The birds do not create it, and they do not remain once it passes. They mark it, briefly, making visible what is otherwise difficult to see.
Bird movement along the shoreline often draws attention toward activity that remains unseen beneath the surface. | Image credit: A. Mitchell
References
Castro, J. I. (1993). The shark nursery of bulls Bay, South Carolina, with a review of the shark nurseries of the southeastern coast of the United States. Environmental Biology of Fishes, 38(1-3), 37-48. https://doi.org/10.1007/bf00842902
Colwell, M. A. (2010). Shorebird ecology, conservation, and management. University of California Press.
Estes, J. A., Terborgh, J., Brashares, J. S., Power, M. E., Berger, J., Bond, W. J., Carpenter, S. R., Essington, T. E., Holt, R. D., C. Jackson, J. B., Marquis, R. J., Oksanen, L., Oksanen, T., Paine, R. T., Pikitch, E. K., Ripple, W. J., Sandin, S. A., Scheffer, M., Schoener, T. W., & Wardle, D. A. (2011). Trophic downgrading of planet Earth. Science, 33(6040), 301-306. https://doi.org/10.1126/science.1205106
Heithaus, M. R., Frid, A., Wirsing, A. J., & Worm, B. (2008). Predicting ecological consequences of marine top predator declines. Trends in Ecology & Evolution, 23(4), 202-210. https://doi.org/10.1016/j.tree.2008.01.003
Heupel, M. R., & Hueter, R. E. (2002). Importance of prey density in relation to the movement patterns of juvenile blacktip sharks ( Carcharhinus limbatus ) within a coastal nursery area. Marine and Freshwater Research, 53(2), 543-550. https://doi.org/10.1071/mf01132
Piersma, T. (1997). Do global patterns of habitat use and migration strategies Co-evolve with relative investments in Immunocompetence due to spatial variation in parasite pressure? Oikos, 80(3), 623-631. https://doi.org/10.2307/3546640
Poole, A. F., Bierregaard, R. O., & Martell, M. S. (2002). Osprey (Pandion haliaetus). In The Birds of North America (1st ed.). Cornell Lab of Ornithology.
Safina, C., & Burger, J. (1985). Common tern foraging: Seasonal trends in prey fish densities and competition with bluefish. Ecology, 66(5), 1457-1463. https://doi.org/10.2307/1938008
Shields, M. (2014). Brown Pelican (Pelecanus occidentalis). In Birds of North America (1st ed.). Cornell Lab of Ornithology.
Wright, L., Short, A., & Green, M. (1985). Short-term changes in the morphodynamic states of beaches and surf zones: An empirical predictive model. Marine Geology, 62(3-4), 339-364. https://doi.org/10.1016/0025-3227(85)90123-9
There’s a version of this story that shows up often—sometimes in films, sometimes in passing explanations—that when a large storm approaches, sharks move into estuaries to escape the violence of the open ocean.
It makes intuitive sense.
The ocean becomes something unmanageable—waves building, wind stacking energy across the surface. And just inland, the estuary appears contained. Narrower. Protected. A place where the water feels like it should be quieter.
But if you stand at the edge of a tidal creek before a storm, what you see first isn’t protection.
It’s change.
The surface tightens. Wind presses across it—not yet breaking it into waves, but organizing it into long, directional movement. The irregular texture of a normal day disappears into something aligned. Purposeful.
Water levels begin to rise before rainfall arrives. The boundary between water and marsh softens. Spartina no longer holds a sharp edge. The ground beneath your feet gives way more easily, saturated beyond its usual resistance.
Water moving through a beach access during storm conditions along the North Carolina coast, as rising levels and wind-driven flow begin to overtake the boundary between ocean and land. | Image credit: J. Armstrong
This is the first shift.
Not force, but redistribution.
And everything in the system is already responding.
What Lives Here When the System Starts Moving
The sharks that use estuaries are not here because these places offer protection from storms.
They are here because of what you can’t always see at first glance.
A juvenile blacktip shark (Carcharhinus limbatus) doesn’t move through open water the way people imagine sharks do. It stays in the shallows—along the edges where the water darkens slightly, where small schools of fish break apart and reform, where the bottom shifts from sand to scattered shell. These areas are harder for larger predators to move through quickly. Not impossible—but slower, more complicated.
Blacktip sharks move through estuaries in Onslow County, North Carolina, using shallow water where depth, structure and movement shape where they travel. | Image credit: kseym001, iNaturalist
That difference matters when you’re small.
What scientists describe as “structure” is this: broken bottom, uneven depth, patches of grass, oyster shell, shadow, current seams. From the shoreline, it just looks like variation. To a young shark, it’s the difference between being exposed and being able to disappear for a second.
That’s why these areas are used as nurseries—not because they are safe, but because they are less predictable in a way that favors smaller animals (Heupel et al., 2007).
From a distance, it looks like open water. Up close, it’s a series of edges—grass, mud, and channels—where movement slows, shifts, and concentrates. | Image credit: A. Mitchell
An Atlantic sharpnose shark (Rhizoprionodon terraenovae) uses that same space differently. You wouldn’t see it cruising the center of a channel. You’d find it where things intersect—along the drop where shallow water slips into deeper flow, near the edges of grass beds, or where current carries small prey out of the marsh and into open water.
It’s not avoiding predators in the same way a juvenile blacktip is.
It’s positioning itself where food moves, while still staying just out of the most exposed water (Ulrich et al., 2007).
Even the bonnethead shark (Sphyrna tiburo)—often described as a “benthic feeder”—is easier to understand if you ignore the word and watch the behavior. It spends time over the bottom, moving slowly across seagrass beds and sandy patches, nosing through the substrate for crabs and small invertebrates.
You’re most likely to notice it not by seeing the whole animal, but by the movement it leaves behind.
A subtle disturbance. A shift in the grass. A shape that doesn’t hold still long enough to resolve.
It’s also one of the few sharks you’re likely to find deeper into the estuary, where the water begins to lose its salt edge. Bonnetheads can tolerate lower salinity than many coastal sharks, which allows them to follow food farther into these mixed waters rather than staying closer to the inlet (Bethea et al., 2007).
Not because it’s calmer there.
Because the feeding opportunities extend into that space.
These sharks are here because the estuary offers layers—places to feed, places to pass through, places where movement is broken up just enough to matter (Knip et al., 2010; Bangley et al., 2018).
But all of those layers depend on something staying consistent—edges holding their shape, water moving in predictable directions, and clarity allowing animals to track one another.
And those are the first things a storm begins to take apart.
The Problem With “Shelter”
When a hurricane approaches, an estuary does not become a refuge.
It becomes harder to read.
If you stand on the ocean side of Topsail Island, you’ll see the change first as energy—waves building, spacing tightening, the surface lifting and falling with more force than it did the day before. But if you cross to the other side of the island—along the Intracoastal Waterway or into Stump Sound—it doesn’t look like that.
There, it rises.
Steadily. Quietly. Without the same visible force.
And that difference is exactly why the idea of “shelter” feels convincing.
On the ocean side, the storm is easier to recognize. Energy builds into waves, making the movement visible in a way it isn’t on the other side of the island. | Image credit: WITN-TV. On the sound side, it doesn’t look like a storm in the same way. The water rises and shifts along the shoreline, even as the system is already building offshore. | Image credit: A. Mitchell
Under normal conditions, these waters are connected—but they don’t move together. Ocean tides enter through New River Inlet and New Topsail Inlet, then work their way through the back-barrier system—the marshes, the Intracoastal, the sounds. That movement slows as it spreads out, which is why tides behind the island can lag the ocean by hours (Friedrichs & Aubrey, 1988).
From the shoreline, it feels like separation.
Like the ocean is doing one thing, and the water behind the island is doing another.
As a storm approaches, that timing begins to compress. Wind pushes water through the inlets faster than the system can distribute it, while water already inside has less opportunity to drain back out.
What was once staggered in time begins to overlap.
Storm surge doesn’t just raise water levels—it disrupts the normal exchange between ocean and estuary, forcing water inland and holding it there longer than a typical tidal cycle (National Oceanic and Atmospheric Administration, 2023).
That’s why the sound side doesn’t look violent at first.
It’s not because it’s protected.
It’s because it’s filling.
You can watch it happen without measuring anything. The usual drop after high tide doesn’t come when you expect it. Water continues to rise or holds in place. The difference between ocean and sound begins to disappear—not because the ocean calms down, but because the back-barrier system begins to behave more like a single body of water under pressure.
Edges blur as marsh grass floods from below. The bottom disappears as suspended sediment increases, and runoff and resuspension mix material into the water column faster than it can settle (Mallin et al., 1999).
The system is no longer cycling. It’s shifting faster than it can recover, with the patterns that usually hold it together breaking down in real time (Resh et al., 1988).
It’s accumulating.
And once that happens, the things that made this environment usable begin to disappear with it.
Where the Larger Sharks Actually Go
If an estuary loses the very structure that makes it usable during a storm, then the question shifts.
Sharks are not staying in place and enduring that change.
They are moving with it.
But not in the way we tend to imagine.
They don’t need to move into something more protected, because the ocean itself isn’t uniform. What looks chaotic at the surface is layered, and that layering holds even as a storm passes overhead. Wave energy dissipates quickly with depth, which means that the violence you see from the beach does not extend indefinitely downward.
A few meters below the surface, movement changes.
Deeper still, it stabilizes.
From above, the structure becomes visible—shallow bars, deeper channels, and the connections between ocean and estuary that shape how water moves through the system. | Image credit: Town of Topsail Beach
For larger coastal sharks like the bull shark (Carcharhinus leucas), that difference matters more than distance from shore. They are not choosing between rough ocean and calm estuary.
They are moving within a three-dimensional space.
And they sense the change before it arrives. It’s the same shift you feel before a storm—the air getting heavier, the pressure dropping, something changing before you can point to it. In the water, that change travels differently, and sharks begin responding to it well before anything looks different at the surface (Papastamatiou et al., 2015).
From the shoreline, it can feel like the storm suddenly arrives. But for animals in the water, it doesn’t. The change builds, and they are already moving within it—shifting position, adjusting depth, following the parts of the system that are still holding together as everything else begins to change long before it’s visible from the shoreline (Heupel et al., 2003).
Where the Shallow-Water Sharks Go
The sharks that spend their time in these shallow systems don’t have the same options as those offshore, because there is no deeper layer to move into when conditions begin to change. Instead, their response is tied to what parts of the system still hold together. As water levels rise and flow patterns begin to shift, the backs of creeks and the shallowest flats are often the first places to lose definition. These are areas where water can become cut off or overly mixed, where direction is no longer consistent, and where the features that usually structure movement begin to disappear.
What follows is not a movement further inland, but a gradual pulling back toward places that remain more stable. That often means deeper channels, intersections where water is still moving in a defined direction, or areas closer to inlets where exchange is still occurring. Rather than leaving the estuary entirely, many individuals consolidate within the portions of it that continue to function in a recognizable way. This kind of movement—shifting position as conditions change rather than holding in place—has been observed in coastal sharks as these systems begin to break down (Heupel et al., 2003).
At the same time, the system itself is expanding beyond its usual boundaries. Storm surge and flooding connect environments that are typically separate, allowing water to move across marsh, into low-lying land, and through built spaces like roads, canals, and retention areas. When that happens, animals already present in the water column move with it, not because they are selecting those environments, but because the physical structure that normally contains them is temporarily absent. Observations of sharks and other marine species in flooded coastal areas are most often associated with these short-lived hydrological connections rather than deliberate movement into unfamiliar habitats (Snelson et al., 1984).
As water spreads across the landscape, the system expands with it—connecting marsh, channels, and developed areas into a single, continuous space. | Image credit: C. Mitchell, AccuWeather
As water recedes, those connections close just as quickly as they formed. The system contracts, and the pathways that briefly allowed movement into those spaces disappear. Animals either move back with the retreating water or are left in conditions that no longer support them. What appears from the outside as unusual behavior is, in most cases, the result of a system that has temporarily lost its boundaries and then reestablished them.
Where the Assumption Breaks
The idea that sharks move into estuaries for shelter during storms rests on a simple assumption: that calmer-looking water offers protection. From the shoreline, that assumption is easy to make. The ocean side of Topsail Island shows the storm first—waves building, energy increasing—while the waters behind the island, along the Intracoastal Waterway and within Stump Sound, often appear quieter in the early stages. But that difference is not a separation of systems. It is a difference in timing.
Under normal conditions, tidal exchange through New River Inlet and New Topsail Inlet distributes ocean energy into the back-barrier environment with a delay, shaped by channel geometry and friction. That lag creates the appearance that one side of the island is responding differently than the other, when in reality both are part of the same connected system (Friedrichs & Aubrey, 1988). As storm conditions intensify, that delay compresses. Water is pushed through the inlets more rapidly than the system can accommodate, and the distinction between ocean and estuary begins to collapse into a single, continuous response driven by surge, wind, and pressure (NOAA, 2023).
Sharks are responding to that shift the entire time, not by seeking out calm water, but by staying within parts of the system that hold their structure for as long as they can. Offshore, that structure exists vertically, allowing movement into deeper, more stable layers. Within estuaries, it exists horizontally and can disappear quickly as gradients break down. The concept of “shelter” depends on the persistence of those gradients—clear edges, directional flow, and predictable relationships between different parts of the system—but during a storm, those features are among the first to be altered.
What remains after the storm is not evidence of animals moving into safer spaces, but the memory of contrast between what those spaces usually are and what they became under changing conditions. That contrast is compelling enough to shape interpretation, even when the underlying processes point to a different explanation.
After the water recedes, the boundary remains shifted—marking where movement passed through, rather than where it began. | Image credit: J. Lester
References
Bangley, C. W., Paramore, L., Shiffman, D. S., & Rulifson, R. A. (2018). Increased abundance and nursery habitat use of the bull shark (Carcharhinus leucas) in response to a changing environment in a warm-temperate Estuary. Scientific Reports, 8(1). https://doi.org/10.1038/s41598-018-24510-z
Bethea, D., Buckel, J., & Carlson, J. (2004). Foraging ecology of the early life stages of four sympatric shark species. Marine Ecology Progress Series, 268, 245-264. https://doi.org/10.3354/meps268245
Ebert, D. A., Dando, M., & Fowler, S. (2021). Sharks of the world: A complete guide. Princeton University Press.
Friedrichs, C. T., & Aubrey, D. G. (1988). Non-linear tidal distortion in shallow well-mixed estuaries: A synthesis. Estuarine, Coastal and Shelf Science, 27(5), 521-545. https://doi.org/10.1016/0272-7714(88)90082-0
Heupel, M., Carlson, J., & Simpfendorfer, C. (2007). Shark nursery areas: Concepts, definition, characterization and assumptions. Marine Ecology Progress Series, 337, 287-297. https://doi.org/10.3354/meps337287
Heupel, M. R., Simpfendorfer, C. A., & Hueter, R. E. (2003). Running before the storm: Blacktip sharks respond to falling barometric pressure associated with tropical storm Gabrielle. Journal of Fish Biology, 63(5), 1357-1363. https://doi.org/10.1046/j.1095-8649.2003.00250.x
Knip, D., Heupel, M., & Simpfendorfer, C. (2010). Sharks in nearshore environments: Models, importance, and consequences. Marine Ecology Progress Series, 402, 1-11. https://doi.org/10.3354/meps08498
Mallin, M. A., Posey, M. H., Shank, G. C., McIver, M. R., Ensign, S. H., & Alphin, T. D. (1999). Hurricane effects on water quality and benthos in the cape fear watershed: Natural and anthropogenic impacts. Ecological Applications, 9(1), 350. https://doi.org/10.2307/2641190
Papastamatiou, Y. P., Watanabe, Y. Y., Bradley, D., Dee, L. E., Weng, K., Lowe, C. G., & Caselle, J. E. (2015). Drivers of daily routines in an ectothermic marine predator: Hunt warm, rest warmer? PLOS ONE, 10(6), e0127807. https://doi.org/10.1371/journal.pone.0127807
Pine, W. E., Pollock, K. H., Hightower, J. E., Kwak, T. J., & Rice, J. A. (2003). A review of tagging methods for estimating fish population size and components of mortality. Fisheries, 28(10), 10-23. https://doi.org/10.1577/1548-8446(2003)28[10:arotmf]2.0.co;2
Resh, V. H., Brown, A. V., Covich, A. P., Gurtz, M. E., Li, H. W., Minshall, G. W., Reice, S. R., Sheldon, A. L., Wallace, J. B., & Wissmar, R. C. (1988). The Role of Disturbance in Stream Ecology. Journal of the North American Benthological Society; Freshwater Science, 7(4). https://doi.org/10.2307/1467300
Ulrich, G. F., Jones, C. M., Driggers III, W. B., Drymon, J. M., Oakley, D., & Riley, C. (2007). Habitat Utilization, Relative Abundance, and Seasonality of Sharks in the Estuarine and Nearshore Waters of South Carolina. American Fisheries Society Symposium, 50, 125-139. https://lowcountryinstitute.org/images/research/dox/Ulrichetal2007.pdf
Valiela, I., & Cole, M. L. (2002). Comparative evidence that salt marshes and mangroves may protect seagrass meadows from land-derived nitrogen loads. Ecosystems, 5(1), 92-102. https://doi.org/10.1007/s10021-001-0058-4
In the last few weeks, the water along the edges of Onslow County has felt different.
Not because the water itself has changed—but because something beneath it has become harder to ignore.
Schools of cownose ray (Rhinoptera bonasus) move just below the surface nearshore, their wingbeats lifting faint clouds from the bottom as they pass. In the soundside shallows, where the water thins over sand and mud, Atlantic stingray (Hypanus sabinus) settle into the substrate, half-buried and nearly invisible until a step comes too close and the outline breaks.
People are seeing them more often now—but they’re also reacting to them.
A pause mid-step in shallow water. A quick shift backward when something moves. Fishermen lifting a line and stopping for a second longer than usual—not what they expected to find.
There is awe in it.
And sometimes hesitation.
Because the same thing that makes them easy to notice now also makes them easy to miss.
The question follows quickly:
Are there more of them this year?
Maybe.
But that question lingers longer than the answer.
Cownose rays migrating in Swansboro, NC. | Image credit: Pogie’s Academy
What Brings Them Here
As spring settles in along the North Carolina coast, the system begins to reorganize.
Water temperatures rise, and with that rise comes a shift in metabolism. Rays—like many coastal species—become more active as conditions move into a narrower range that supports feeding and movement (Smith & Merriner, 1987; Schwartz & Dahlberg, 1978).
For cownose rays, this seasonal transition includes a northward migration along the Atlantic coast, bringing large groups into nearshore and estuarine waters (Smith & Merriner, 1987).
Large groups of cownose rays like these move north along our coast each season, arriving together in shallow water. | Image credit: Vidyacharan A. Alchi
But movement alone does not explain what people are seeing.
What matters is where that movement meets the structure of the environment.
The water does not always look the same—some days it is flat and clear enough to see straight to the bottom, and other days the slightest movement turns it cloudy, changing what can be seen and what remains hidden (Peterson et al., 2001).
And beneath all of it is food.
Cownose rays move through the shallows, sweeping across the bottom and disrupting what lies beneath them, crushing clams, oysters, and other shelled invertebrates with broad, flattened tooth plates (Collins et al., 2007; Fisher, 2010).
Atlantic stingrays hold low against the bottom, burying into the sand as they feed and working within the sediment itself—not moving across it—uncovering and drawing in small invertebrates hidden below (Snelson et al., 1988; Schwartz & Dahlberg, 1978).
Atlantic stingrays hold close to the bottom, often blending in until something shifts and gives them away. | Image credit: Andy Murch
Where prey is accessible, rays follow.
Where prey is concentrated in shallow, warming water, rays do not just pass through—they stay, turn, feed, and linger.
And in doing so, they cross into the same narrow band of space where people enter the water (Bangley et al., 2018).
They are not simply “here more.”
They are here in ways—and in places—that make them visible.
What Happens When They Feed
When a ray feeds, the bottom does not remain the same.
A cownose ray moving across a flat is not just searching—it is actively restructuring the surface beneath it. As it passes, the bottom is turned over behind it, patches of sand and mud disturbed where clams and other buried life have just been uncovered and crushed (Peterson et al., 2001; Smith & Merriner, 1985).
Feeding pits left behind by rays. Easy to mistake for crab holes at first—until you start to recognize the pattern and what’s actually shaping the bottom. | Image credit: Giaroli et al., 2024
Atlantic stingrays leave a different kind of trace. Where they settle, the surface shifts more subtly—small depressions, softened patches, places where the sediment has been worked rather than overturned, as buried invertebrates are uncovered and drawn in (Snelson et al., 1988; Schwartz & Dahlberg, 1978).
This is bioturbation—the bottom being reworked by the animals moving through it and within it (Thrush & Dayton, 2002).
As they feed, the bottom lifts into the water—fine particles rising and hanging there, turning clear water slightly cloudy (Thrush & Dayton, 2002).
Oysters and clams quietly filter the water as they feed, and when their numbers shift—even in small areas—the water and everything moving through it begins to change with them (Newell, 2004; zu Ermgassen et al., 2013).
In places where rays have been feeding, those filtering communities can be reduced or redistributed (Peterson et al., 2001).
Not removed entirely—but changed.
And that change does not stay in one place.
It moves outward, carried in the way the water looks, the way it settles, and what it can hold.
Layers of the Food Web
Rays do not sit at the top of the system, and they are not at the bottom of it.
As mesopredators, they feed on what is buried in the sediment, but they are also available to what moves through the water above. That position—between—links parts of the system that do not often meet directly (Myers et al., 2007; Heithaus et al., 2008).
What they do in that space matters.
As cownose rays move through andAtlantic stingrays work within the bottom, they are not just feeding—they are shaping what persists there. Clams, oysters, and other invertebrates do not simply accumulate unchecked. Their numbers are reduced, redistributed, and in some places kept from becoming dominant (Peterson et al., 2001).
Movement like this doesn’t stay in one place for long.
That pressure shapes the bottom itself.
Bivalves filter the water. Invertebrates stabilize sediment. When their abundance shifts, the system responds—sometimes toward clearer water, sometimes toward more suspended material, depending on what remains and where (Newell, 2004; zu Ermgassen et al., 2013).
Rays do not create those conditions alone—but they influence which direction the system moves.
At the same time, they carry that energy upward.
Juvenile sharks moving through these shallow waters encounter not just prey, but a system already in motion—areas where the bottom has been disturbed, where feeding has recently occurred, where something has been uncovered or displaced (Bangley et al., 2018).
And in some cases, the rays themselves become part of that exchange.
This is what it means to sit in the middle.
Not just connecting layers—but regulating how energy and movement pass between them.
If that middle shifts, the balance does not disappear.
It changes direction.
Why It Feels Sudden
There is a moment, standing in shallow water, when the bottom stops feeling like something you can trust.
What looked like sand shifts. What felt still is no longer still.
Sometimes you notice it in time—a shape lifting away, a shadow moving just beneath the surface. A plume of fine sediment rising to the surface under a paddleboard with a trail following it.
The moment when the bottom stops looking empty. | Image credit: iStock
Sometimes you don’t.
A step comes down where something is already settled. Hidden in the sand. Working within it.
The reaction is immediate. Surprise first. Then pain. Then the realization of what was there all along.
But what you are stepping into is not a single event.
It is a convergence.
Water temperatures have risen, bringing rays into the shallows as they feed and move through these systems (Smith & Merriner, 1987; Schwartz & Dahlberg, 1978).
Tides narrow the space, concentrating movement into a thinner band of water.
The bottom has already been worked—turned by cownose rays moving through, disturbed by Atlantic stingrays holding within it.
And at the same time, people have returned to the water.
For a brief window, all of it overlaps.
Not more. But more visible.
It feels sudden because you are standing at the point where all of these things meet.
And for a moment, the system lets you see it.
References
Bangley, C. W., Paramore, L., Dedman, S., & Rulifson, R. A. (2018). Delineation and mapping of coastal shark habitat within a shallow lagoonal Estuary. PLOS ONE, 13(4), e0195221. https://doi.org/10.1371/journal.pone.0195221
Giaroli, M. L., Byrne, I., Gilby, B. L., Taylor, M., Chargulaf, C. A., & Tibbetts, I. R. (2024). The distribution and significance of stingray feeding pits in Quandamooka (Moreton Bay), Australia. Marine and Freshwater Research, 75(18). https://doi.org/10.1071/mf23247
Heithaus, M. R., Frid, A., Wirsing, A. J., & Worm, B. (2008). Predicting ecological consequences of marine top predator declines. Trends in Ecology & Evolution, 23(4), 202-210. https://doi.org/10.1016/j.tree.2008.01.003
Kolmann, M. A., Huber, D. R., Motta, P. J., & Grubbs, R. D. (2015). Feeding biomechanics of the cownose ray, Rhinoptera bonasus, over ontogeny. Journal of Anatomy, 227(3), 341-351. https://onlinelibrary.wiley.com/doi/full/10.1111/joa.12342
Myers, R. A., Baum, J. K., Shepherd, T. D., Powers, S. P., & Peterson, C. H. (2007). Cascading effects of the loss of APEX predatory sharks from a coastal ocean. Science, 315(5820), 1846-1850. https://doi.org/10.1126/science.1138657
Newell, R. I. (2004). Ecosystem influences of natural and cultivated populations of suspension-feeding bivalve molluscs: A review. 23(1), 51–61. Journal of Shellfish Research, 23(1), 51-61. https://go.gale.com/ps/i.do?id=GALE%7CA118543914
Peterson, C. H., Fodrie, J. F., Summerson, H. C., & Powers, S. P. (2001). Site-specific and density-dependent extinction of prey by schooling rays: generation of a population sink in top-quality habitat for bay scallops. Oecologia, 129, 349-356. https://link.springer.com/article/10.1007/s004420100742
Schwartz, F. J., & Dahlberg, M. D. (1978). Biology and ecology of the Atlantic Stingray, Dasyatis Sabina (Pisces: Dasyatidae) in North Carolina and Georgia. Northeast Gulf Science, 2(1). https://doi.org/10.18785/negs.0201.01
Smith, J. W., & Merriner, J. V. (1985). Food habits and feeding behavior of the Cownose ray, Rhinoptera bonasus, in lower Chesapeake Bay. Estuaries, 8(3), 305. https://doi.org/10.2307/1351491
Smith, J. W., & Merriner, J. V. (1987). Age and growth, movements and distribution of the Cownose ray, Rhinoptera bonasus, in Chesapeake Bay. Estuaries, 10(2), 153. https://doi.org/10.2307/1352180
Snelson, F. F., Williams-Hooper, S. E., & Schmid, T. H. (1988). Reproduction and ecology of the Atlantic Stingray, Dasyatis Sabina, in Florida coastal lagoons. Copeia, 1988(3), 729. https://doi.org/10.2307/1445395
Thrush, S. F., & Dayton, P. K. (2002). Disturbance to marine benthic habitats by trawling and dredging: Implications for marine biodiversity. Annual Review of Ecology and Systematics, 33(1), 449-473. https://doi.org/10.1146/annurev.ecolsys.33.010802.150515
Zu Ermgassen, P. S., Spalding, M. D., Blake, B., Coen, L. D., Dumbauld, B., Geiger, S., Grabowski, J. H., Grizzle, R., Luckenbach, M., McGraw, K., Rodney, W., Ruesink, J. L., Powers, S. P., & Brumbaugh, R. (2012). Historical ecology with real numbers: Past and present extent and biomass of an imperilled estuarine habitat. Proceedings of the Royal Society B: Biological Sciences, 279(1742), 3393-3400. https://doi.org/10.1098/rspb.2012.0313
There are mornings along the edges of the water in Onslow County when the surface looks still enough to trust.
The marsh grass has not yet reached its summer height. What stands there leaves more water exposed between the stems, and without sustained wind, the surface holds its shape. You can see farther into it now than you will in a few weeks, before suspended sediment and constant movement return it to opacity. The water carries less of the season, and because of that, more of what moves beneath it becomes visible—if you are willing to wait long enough to see the difference between movement and reflection.
This is when people begin to notice them again.
Not all at once. Not everywhere. Just a change that does not follow wind or tide. A line that holds where the rest of the surface releases. Something that holds its position in a system that is always adjusting.
An alligator does not arrive in that moment.
It becomes visible.
Alligator emerging from the mud. | Photo credit: Gilbert Grant, iNaturalist
Seasonal Absence Is Not Absence
Through winter, they remain within these same creeks, marsh edges, and quieter channels. What changes is not location, but how they occupy it. As temperatures fall, activity narrows. Movement slows, and the need for it slows with it. Energy is conserved, not spent. And the surface carries fewer signs of what lies beneath it. Individuals hold in deeper water or along softer margins where mud retains heat longer than the surrounding water column, remaining within conditions that allow them to persist without constant movement (Nifong et al., 2014; Rosenblatt & Heithaus, 2011).
The same stretch of water that in spring will hold a visible form can pass through winter without interruption, its stillness mistaken for absence.
But the system does not empty.
It compresses.
The System Wakes in Layers
By early spring, that compression begins to release—not all at once, but in layers that build on each other before they are recognized. Shallow water warms first, taking in solar heat more quickly than deeper channels. Along these edges, fish begin to hold longer. Movements that in winter passed through quickly begin to extend into areas that had remained quiet. Invertebrates return to the sediment surface, and the water column begins to carry more suspended life, even before it becomes visible as turbidity.
Birds respond to this before most other changes are noticed. Their movements tighten. Landings become more frequent, departures more abrupt. What they are tracking is not random. It is the redistribution of energy into places where it can be accessed.
The alligator moves within that shift.
Not as a trigger. Not as something layered on top. But as part of a system reorganizing itself across temperature, light, and movement at the same time.
Great blue heron and alligator are part of an interconnected system. | Photo credit: Audubon North Carolina
Reading What It Is Responding To
When one becomes visible along the edge of a creek or marsh, it is easy to reduce that moment to temperature alone. Warmer water allows for more activity.
But what draws it into that position is more specific than warmth.
It is the arrangement of prey.
Along the margins where water meets land, movement compresses. Fish traveling with the tide encounter shallow gradients that limit how long they can remain. Small mammals moving between marsh and upland must cross exposed edges. Birds landing to feed do so in places where depth and access align for only short intervals.
These are not isolated events. They are recurring patterns shaped by tidal cycles, substrate, and seasonal change.
The alligator positions itself within those patterns.
Its diet reflects that flexibility, spanning invertebrates, fish, birds, reptiles, and mammals depending on size and availability (Nifong, 2016). But the diet alone does not explain its placement. What matters is where energy becomes concentrated, even briefly.
That concentration is not constant. It forms and dissolves with tide, with light, with movement.
And the predator tracks that.
And what appears as a single movement—a fish turning, a bird lifting, something crossing the edge of the marsh—is part of a larger structure that holds only briefly before dissolving again.
The alligator does not respond to the individual movement.
It responds to the pattern that produces it.
Where Freshwater Meets Salt
These are not just places where water mixes.
They are places where movement is forced—and where that movement becomes available to something waiting at the top of it.
There are places along this coastline where those changes concentrate.
At the mouths of creeks, along the edges of the Intracoastal Waterway, and near the shifting bars of New River Inlet, the water does not settle into a single condition. Freshwater moves outward with tide and rainfall, meeting saltwater pressing back in with tidal exchange. The result is not a fixed boundary, but a gradient that shifts continuously—sometimes visible as a faint line, sometimes only detectable in how the surface moves differently from one side to the other.
This is where alligators are most often encountered—because this is where the system compresses into something they can use.
They are not marine animals. They do not possess the specialized salt glands that allow for extended life in high salinity environments. Over time, saltwater carries a physiological cost, requiring a return to freshwater to restore balance (Rosenblatt & Heithaus, 2011; Fujisaki et al., 2014).
But that limitation does not exclude them.
It defines how they move through them.
In these mixing zones, salinity is not constant. It rises and falls with tide, with rainfall, with wind direction. A location that carries higher salinity at one stage may shift toward fresher conditions hours later. What appears to be a boundary is, in practice, a moving field.
Within that field, movement compresses.
Fish traveling with the tide are funneled into narrower pathways. Shallow gradients limit how long they can remain in deeper water. Schools tighten. Individuals encounter edges that restrict escape. The system concentrates energy into space.
The predator does not need to range widely in these conditions.
It needs to hold where movement is forced.
And so it does.
An alligator near the tall grass near Marine Corps Air Station New River | Photo credit: Martin Egnash
At the Edge of the Open Water
There are moments when that pattern extends beyond the mixing zones, into places that appear, at first, outside of where an alligator belongs.
Along the shoreline, in the breaking waves where the ocean meets sand, one will sometimes appear—rising and falling with the swell, holding position just beyond where the water turns over onto the beach. It looks misplaced, as though it has moved beyond the system that defines it.
It has not.
The surf zone is one of the most compressed environments along the coast. Waves reduce depth, disrupt orientation, and concentrate movement into a narrow band where escape is limited. Fish pushed into breaking water lose some ability to maintain direction. Schools fragment. Individuals become briefly exposed in ways that do not occur in deeper, more stable water.
For a predator capable of stillness followed by short bursts of movement, that compression creates opportunity.
But the cost is higher.
Salinity is elevated. The water is in constant motion. There is no stable refuge within immediate reach. Time in this environment cannot be extended indefinitely.
And so it does not.
Movements into higher salinity water tend to be brief—extensions outward, followed by a return to freshwater or lower salinity conditions where balance can be restored (Nifong et al., 2014).
What appears as an anomaly is part of a larger pattern.
The predator crosses the boundary not to remain, but to use it, moving where the system briefly offers more than it costs.
The same forces that shape the marsh edge—compression, constraint, and brief exposure—are recreated here, just for a moment, in a different place.
An alligator rests at the ocean’s edge in North Topsail. | Photo credit: Fox8 Digital Desk
What Its Presence Changes
Most of what that presence changes cannot be seen when it is observed.
Long before any direct interaction occurs, it is already altering how other organisms use space.
Fish moving along the edge do not simply pass through. They adjust their depth, their speed, the amount of time they remain exposed. Birds land with shorter intervals between contact and departure. Mammals approaching the water shift their paths or their timing. These changes are not dramatic in isolation. But they are continuous.
Over time, they accumulate into structure—the kind that determines who feeds, where they feed, and how long they remain.
The influence of a predator at this level extends beyond what it consumes. It shapes behavior across multiple species, redistributing where and how energy moves through the system. The possibility of predation—present even when not observed—alters interactions in ways that regulate access to habitat and resources (Heithaus et al., 2008; Ripple et al., 2014; Estes et al., 2011).
What holds the system in place is not removal alone.
It is pressure.
What is being shaped is not just movement, but access—and access is what determines how energy moves through the system.
More Than Predation
The influence of the alligator does not end with what it hunts, but extends beyond those interactions.
As it moves through shallow systems, it disturbs sediment, creating depressions and pathways that alter how water is retained and how nutrients are redistributed. These small changes in physical structure create conditions that other species use—temporary refuges, feeding areas, and zones where organic material accumulates (Eversole et al., 2018; Subalusky et al., 2009).
In wetland systems, these disturbances have been linked to broader effects, including nutrient cycling and carbon storage, where the presence of large predators contributes to the retention of organic material within the system rather than its export (Murray et al., 2025; Atwood et al., 2015).
These processes do not occur in isolation.
They intersect with the same patterns of movement, feeding, and behavior that define the system at larger scales.
Seeing the Surface, Reading the System
When one becomes visible along the surface, it is easy to treat the moment as singular.
A sighting. An encounter. Something separate from everything around it.
But that form at the surface is supported by layers extending beyond what can be seen.
It reflects water temperatures crossing into ranges that support sustained activity. It reflects prey moving into positions where access becomes possible. It reflects a system where behavior is still shaped by the presence of something at the top.
The alligator is not an interruption to that system.
It is an expression of it.
What Becomes Visible
Seeing one does not indicate that something has entered the water.
It indicates that enough beneath the surface is functioning to hold it.
Not in a static sense. Not as balance in the way it is often described. But as a set of interactions that remain connected—movement, response, pressure—each shaping the others even when they are not directly observed.
What becomes visible at the surface is only a fraction of that structure.
But it is enough to know that the rest is still in place.
An alligator in Onslow County sits at the edge of the saltmarsh. |Photo credit: Gilbert Grant, iNaturalist
When That Pressure Is Reduced
If that pressure is reduced, the system does not leave an obvious gap.
It shifts.
Movements that were once constrained begin to extend. Species that passed quickly through exposed areas begin to remain longer. Edges that functioned as transition zones become used differently—not because the physical environment has changed, but because the conditions that shaped behavior within it have relaxed.
Mid-level predators expand their activity under these conditions, increasing their access to prey and space when not constrained from above (Nifong et al., 2013).
The change is subtle.
It appears in how long something stays. In how often it returns. In where it lingers. In how quietly the structure of behavior begins to loosen.
The food web and trophic cascade of the American alligator in the Florida Everglades.
A System Written Into Temperature
There is another layer to this that does not show itself at the surface.
The structure of that presence is set years earlier, in a place that can be overlooked when standing at the water’s edge. Along the margins of marsh and wetland, slightly above the reach of regular water movement, nests are built from vegetation and sediment, forming mounds that hold heat as they decompose.
Within those mounds, temperature determines something that will not be visible for much later.
Sex is not fixed at fertilization. It emerges during incubation, shaped by the thermal conditions held within the nest. A difference of only a few degrees is enough to shift the outcome, producing more males or more females depending on where within that range the nest remains (Lang & Andrews, 1994; Janzen, 1994).
Under variable conditions—differences in shading, rainfall, timing, and placement—those outcomes are distributed across the landscape. Some nests produce more females, others more males. That variability holds the population in a form that can sustain itself over time.
When conditions become more consistent, that variation narrows.
Warmer nights hold heat longer within the nest. Seasonal transitions extend. The range of outcomes compresses. What was once distributed begins to align.
And that alignment carries forward into the structure of the population—into how individuals occupy space, into how pressure is applied across the system, into what will eventually be visible at the surface.
Alligator eggs hatch after 65 days of incubation in the fall. The babies will chirp to alert their mom, who then digs out the nest while the babies use their egg tooth to hatch from their eggs. Their mom will then safely carry them to the water.
Where the Next Generation Is Set
The placement of those nests depends on something even more constrained.
A narrow band of land that remains above water just long enough to hold them.
That band is not fixed.
It shifts with tide, with rainfall, with the gradual reworking of shoreline that occurs across seasons and years. With rising sea levels, water reaches farther into areas that once remained above it. Flooding becomes more frequent, not always through singular events, but through repeated intrusions that saturate and destabilize what had previously held (Joanen & McNease, 1989; Sweet et al., 2022).
Human alteration compresses this space further.
Hardened shorelines, dredging, and development reduce the gradual transition between land and water. Where there was once a slope capable of holding multiple elevations, there becomes a defined edge. That edge does not provide the same range of conditions required for successful nesting.
The number of suitable sites decreases.
More importantly, the variability between them narrows.
And with that, the system loses one of the mechanisms that allowed it to absorb change.
Alligator on her nest that can hold up to 60 eggs. | Photo credit: National Park Service (NPS)
What Its Presence Means
When an alligator becomes visible along the surface, it reflects conditions that have aligned across multiple layers.
Temperature has reached a range that supports activity. Prey has moved into positions where access becomes possible. Behavioral pressure remains in place across the system. Reproduction has held across enough years, in enough suitable places, to sustain what is now present.
What is seen at the surface is not separate from them.
It is supported by them.
Seeing one does not signal that something has entered the water.
It signals that enough of what lies beneath it—movement, pressure, response, and continuity—remains intact.
And that—even when most of it is not visible—the system is still holding together.
And that is what becomes visible—just long enough to be seen, before the system closes back over it again.
The system does not end at the water’s edge.
Epilogue: Chicken Nugget
We came across him along the New River, near the courthouse in Jacksonville.
We were there to clear what had been left behind—fishing line caught along the walkways, hooks, and the overflow from a trash can that had spilled out onto the edge. Fast food containers, grocery store chicken trays, scattered along the bank. The signs were clear enough. People had been there for a while—crabbing, fishing, eating, leaving what remained.
He was directly below us.
Small enough to miss at first. Still enough to blend into the water until you stopped looking for movement and started noticing what held its position.
A juvenile alligator, watching.
He stayed there while we worked, then slipped beneath the surface and crossed the small bay. On the opposite side, someone tossed a piece of food into the water. He surfaced almost immediately, took it, and remained.
Waiting.
I came back later and stayed longer.
The pattern repeated. He would disappear until footsteps approached, then return to the same place along the edge. Holding position. Watching. Waiting for something to fall.
No fishermen or crabbers passed through while I was there, but the behavior was consistent with what happens when food becomes predictable. Bait, catch, scraps—anything that can be taken without the cost of searching or pursuing.
Energy, without effort.
It is easy to see something like that and respond to what it looks like in that moment. A small animal. Still. Attentive. Something that feels close enough to interact with.
But what is being shaped there is not just a single interaction.
It is behavior.
A shift away from the conditions that formed it—toward something more efficient, more immediate, and less stable over time. The system that once required movement, patience, and response begins to narrow into expectation.
And expectation changes how an animal uses space.
What happens when that animal is no longer small is not a separate question.
It is the continuation of the same pattern.
Alligators do not forget where food has been easy to obtain. They return to it. They hold in those places. They begin to associate presence—human presence—with opportunity.
What begins as something that feels harmless becomes something that alters how the system functions around it.
Not just for the animal, but for everything that responds to it.
There are instincts at work here that were shaped long before any walkway, any dock, any place where food might be dropped from above. Those instincts are not just about survival in isolation. They are part of how pressure is applied, how movement is shaped, how the system holds.
When those instincts are replaced with something easier, the effect does not remain contained.
It carries outward.
He stayed there while I watched. Returning to the same place. Holding the same position. Waiting for something to fall.
There is a kind of kindness in wanting to give something to an animal like that.
But there is another kind in leaving it as it is.
Not interrupting the conditions that shape it. Not narrowing what it has learned to expect. Not replacing a system built on movement and response with one built on waiting.
Let it remember the water as it is.
And you, only as something that passed through it.
We affectionately named this juvenile alligator in the New River in Jacksonville, NC “Chicken Nugget” for all of the chicken nugget boxes left behind on the walkway from an overflowing trash can. | Photo credit: A. Mitchell
References
Atwood, T. B., Connolly, R. M., Ritchie, E. G., Lovelock, C. E., Heithaus, M. R., Hays, G. C., Fourqurean, J. W., & Macreadie, P. I. (2015). Predators help protect carbon stocks in blue carbon ecosystems. Nature Climate Change, 5(12), 1038-1045. https://doi.org/10.1038/nclimate2763
Estes, J. A., Terbough, J., Brashares, J. S., Power, M. E., Berger, J., Bond, W. J., Carpenter, S. R., Essington, T. E., Holt, R. D., & Wardle, D. A. (2011). Trophic Downgrading of Planet Earth. Science, 333(604), 301-306. https://www.science.org/doi/abs/10.1126/science.1205106
Fujisaki, I., Hart, K. M., Mazzotti, F. J., Cherkiss, M. S., Sartain, A. R., Jeffery, B. M., Beauchamp, J. S., & Denton, M. (2014). Home range and movements of American alligators (Alligator mississippiensis) in an Estuary habitat. Animal Biotelemetry, 2(1), 8. https://doi.org/10.1186/2050-3385-2-8
Heithaus, M. R., Frid, A., Wirsing, A. J., & Worm, B. (2008). Predicting ecological consequences of marine top predator declines. Trends in Ecology & Evolution, 23(4), 202-210. https://doi.org/10.1016/j.tree.2008.01.003
Janzen, F. J. (1994). Climate change and temperature-dependent sex determination in reptiles. PNAS, 91(16), 7487-7490. https://doi.org/10.1073/pnas.91.16.7487
Joanen, T., & McNease, L. L. (1989). Ecology and physiology of nesting and early development of the American alligator. American Zoologist, 29(3), 987-998. https://doi.org/10.1093/icb/29.3.987
Lang, J. W., & Andrews, H. V. (1994). Temperature‐dependent sex determination in crocodilians. Journal of Experimental Zoology, 270(1), 28-44. https://doi.org/10.1002/jez.1402700105
Nifong, J. C. (2016). Living on the edge: Trophic ecology of alligator mississippiensis (American alligator) with access to a shallow estuarine impoundment. Bulletin of the Florida Museum of Natural History, 54(2), 13-49. https://doi.org/10.58782/flmnh.xkdw7119
Nifong, J. C., Nifong, R. L., Silliman, B. R., Lowers, R. H., Guillette, L. J., Ferguson, J. M., Welsh, M., Abernathy, K., & Marshall, G. (2014). Animal-borne imaging reveals novel insights into the foraging behaviors and Diel activity of a large-bodied APEX predator, the American alligator (Alligator mississippiensis). PLoS ONE, 9(1), e83953. https://doi.org/10.1371/journal.pone.0083953
Nifong, J. C., & Silliman, B. R. (2013). Impacts of a large-bodied, APEX predator (Alligator mississippiensis Daudin 1801) on salt marsh food webs. Journal of Experimental Marine Biology and Ecology, 440, 185-191. https://doi.org/10.1016/j.jembe.2013.01.002
Ripple, W. J., Estes, J. A., Beschta, R. L., Wilmers, C. C., Ritchie, E. G., Hebblewhite, M., Berger, J., Elmhagen, B., Letnic, M., Nelson, M. P., Schmitz, O. J., Smith, D. W., Wallach, A. D., & Wirsing, A. J. (2014). Status and ecological effects of the world’s largest carnivores. Science, 343(6167). https://doi.org/10.1126/science.1241484
Rosenblatt, A. E., & Heithaus, M. R. (2011). Does variation in movement tactics and trophic interactions among American alligators create habitat linkages? Journal of Animal Ecology, 80(4), 786-798. https://doi.org/10.1111/j.1365-2656.2011.01830.x
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Encountering the Past in the Sand: When the Beach Opens
There are mornings when the beach feels newly made.
The tide has pulled back just enough to smooth the sand into a long, pale sheet, the wind from the night before erased except for faint ripples that catch the light at an angle. Ghost crab tracks cross and recross the surface, stitching together small territories that vanish with the next wave. The wrack line sits just above the reach of the water—shells, grasses, fragments of offshore life placed carefully along a boundary that shifts a little each day.
And then, walking that line, something interrupts the pattern.
At first it looks like driftwood. Dark. Angular. Out of place, but not unusual. But the closer you get, the more it resists that explanation. The pieces are too regular, too aligned. The sand around it feels different underfoot—firmer, compacted, as though something beneath it has been holding shape long before this tide receded.
What emerges is not debris, but structure.
Ribs of timber curve in a way that only makes sense once you recognize them as part of a hull. Iron fastenings stain deep into the grain. The geometry of a vessel that once moved across this water now rests within it.
The beach has not received this. It has revealed it.
What remains of the William H. Sumner when shifting sand briefly reveals it along the shoreline. | Photo credit: A. Mitchell
Along the Onslow County coast, shipwrecks do not arrive as singular events. They exist in cycles of concealment and return. Storms strip sand away. Longshore currents redistribute what was settled. A wreck that has been buried for decades can appear in a single tide cycle, as if placed there overnight, only to be covered again before the week ends.
The shoreline is not a surface. It is a moving archive (Riggs & Ames, 2003).
A Coast That Does Not Hold Still
Standing at the edge of the water, the coastline can appear steady, almost fixed, as though the boundary between land and ocean has settled into a reliable position. The horizon holds its line. Waves repeat their approach in familiar intervals. Even the inlets, from a distance, seem to occupy defined openings in the land.
But that stability is a surface impression.
Beneath it, the coastline is in constant adjustment. Sand moves even when the water appears calm, carried alongshore by currents that shift direction with changing wind and wave conditions. Bars form offshore, migrate, and dissolve. Channels deepen and fill. The openings at places like New River Inlet or Topsail are not permanent features so much as temporary alignments of water and sediment, reshaped seasonally and sometimes abruptly after storms.
For someone approaching from offshore, especially before modern navigation, this would not have presented as a clear pathway but as uncertainty. Depth changes could occur over short distances. A channel that allowed passage one season might be obstructed the next. What looked like open water could rise into a shoal just beneath the surface, invisible until it was encountered.
Ships moving along this coast were not simply traveling past it. They were moving across a landscape that was itself in motion.
When a vessel grounded here, it was often not because of a single error, but because the environment it relied on for passage had already changed. The ship met a bottom that no longer matched expectation, and once contact was made, wave energy did the rest—breaking the structure apart and distributing its remains across the same shifting system that had caused the grounding.
Over time, those remains became part of that movement. Buried, exposed, and buried again as sand continued to migrate, they settled into the coastline not as isolated events but as elements within an ongoing process.
What appears now as a sudden discovery—a line of timbers revealed after a storm—is not the arrival of something new, but a brief moment when the motion of the coast allows what has long been present to be seen again.
Vessels Carried Into This Coast
An early French map depicting the coastal regions of the Carolinas and Georgia before the American Revolution from an antique map, the “Carte de la Caroline et Georgie” by Jacques-Nicolas Bellin, published around 1773.
Walk this shoreline long enough and shipwrecks begin to feel less like isolated events and more like recurring encounters with the same conditions. Different vessels, different centuries, but the same meeting between movement and a coast that does not stay where it was. What changes is not only the vessel, but the way it is lost.
Two Ways a Ship Becomes Part of the Sea
Not all shipwrecks begin the same way. Some are lost far offshore, where depth replaces sand as the defining feature. A vessel may be damaged by storm, fire, or attack, take on water, and settle downward through open water until it reaches the seafloor. The descent is vertical, the structure often remaining largely intact as it comes to rest in deeper, more stable conditions. These wrecks lie beyond the horizon, where the bottom changes more slowly and the surrounding water does not rearrange them in the same way (Ward et al., 1999; Hoyt et al., 2021).
Others meet the coast itself. Along barrier shorelines like Onslow County, ships often do not sink all at once. They run aground. A hull meets sand where water had been expected, forward motion stops, and the energy of waves and tide begins to work against the structure. The vessel lifts, pivots, and settles unevenly as water moves beneath and around it. Over time, it breaks apart. What remains is not a single intact form, but a field of structure distributed across the seabed and shoreline (Riggs & Ames, 2003; Pilkey, 1998).
Both are shipwrecks, but they belong to different processes. One settles into depth. The other becomes part of a coast that does not hold still.
Pirate Waters
Model of the Queen Anne’s Revenge | Photo credit: Qualiesin, licensed under CC BY-SA 4.0.
Long before modern navigation, these waters were already understood as difficult to pass through cleanly. The channels around what is now Topsail Island were narrow, shifting, and often uncertain from offshore. What appears now as a continuous coastline is, and always has been, a series of openings that do not hold their shape for long.
Even today, that instability can be seen without leaving shore. After a strong storm or a week of changing wind, the edge of the waterline shifts, bars appear where there had been none, and shallow areas extend farther out than expected. A stretch of water that looked open a few days earlier begins to break differently, waves lifting and folding over something just beneath the surface. The bottom has moved, even if the horizon has not (Riggs & Ames, 2003; Pilkey, 1998).
For a vessel approaching from offshore, especially without precise depth measurements, that change would not be visible until it was too late. The hull would meet sand where water had been expected. Forward motion would slow abruptly, then stop, while the energy of the sea continued to act on the vessel. Waves begin to lift and drop the structure unevenly, pivoting it sideways, driving it further onto the bar. What had been a path forward becomes a fixed point under pressure (Riggs et al., 1995; Delgado, 1997).
Stories persist that pirates used this uncertainty to their advantage, positioning themselves within these shifting inlets where passing ships were forced into slower, more confined routes. Whether or not every account is precise, the setting itself made such encounters possible.Further north along this same coastline, in 1718, Blackbeard ran his flagship Queen Anne’s Revenge aground while entering what is now Beaufort Inlet. The ship struck a shallow shoal at the mouth of the inlet, where water depths even today remain modest—on the order of twenty to twenty-five feet at the wreck site. Rather than sinking intact into the deep ocean, it remained within a high-energy, shallow environment where waves and tidal currents gradually broke it apart. Its remains settled into the seabed and have since been buried and re-exposed as sediment continues to move across the inlet (Wilde-Ramsey & Carnes-McNaughton, 2016; Wilde-Ramsing & Carnes-McNaughton, 2018).
To learn more about Blackbeard’s Queen Anne’s Revenge Shipwreck, watch the Nautilus Productions video.
Colonial Trade and Storm-Driven Wrecks
By the mid-eighteenth century, heavily loaded merchant vessels were moving along this coastline as part of transatlantic trade. Their routes followed currents that offered efficiency, but those same currents carried them close to a shoreline that did not remain fixed.
In 1750, the Spanish ship El Salvador, part of a treasure fleet transporting gold and silver, encountered a hurricane that pushed it northward along the Gulf Stream. The storm did not introduce danger so much as concentrate it. Wind and current worked together, driving the vessel toward a coast already defined by shifting shoals and unstable inlets. Other ships in the same fleet were carried along the same path, driven ashore at different points along the Outer Banks, separated from one another by the same forces that moved them north (Shomette, 2008; Pilkey, 1998).
When El Salvador met the shoals, there was little margin left for recovery.
Only a small number of crew survived, carried ashore as the vessel came apart in the surf. The hull did not settle into the water as a whole. Instead, waves lifted and broke it against a bottom that would not hold it in one place. For a short time, portions of the structure remained visible—rigging, fragments of timber, the outline of something that had recently been intact. And then the shoreline resumed its movement. Sand shifted across what remained. Water moved through it. What had been a vessel became something distributed, its structure absorbed into sediment and carried within the same system that had stopped it, continuing to migrate along the coast (Riggs & Ames, 2003; Pilkey, 1998; Shomette, 2008).
The pattern holds: a vessel enters under force, meets a shifting bottom, and becomes part of it.
Steam and Certainty: Pulaski (1838)
The Pulaski is depicted during its boiler explosion | Image credit: C. Elms
By the early nineteenth century, steam navigation had begun to change expectations. Routes were more regular. Travel felt more predictable. Distance could be measured in time rather than uncertainty.
The coastline, however, had not changed.
When the steamship Pulaski exploded offshore of North Carolina in 1838, the rupture was immediate. What followed did not resolve as quickly. Survivors, separated into lifeboats and fragments of wreckage, were no longer traveling across water with direction. They were moving within it (North Carolina Department of Natural and Cultural Resources [DNCR], 2016).
They drifted for more than a day, in some cases closer to two.
There was no fixed path in that movement. Coordinates were not precisely recorded, and what direction remained was shaped by current, wind, and wave rather than intention. The horizon held its line, but offered no reference. The sun marked time without marking progress. Salt settled into the skin. Thirst extended the length of the day. Movement continued, but without a way to measure where it led.
Some survivors eventually reached the barrier islands along this stretch of North Carolina, carried by those same forces rather than guided toward land. Their arrival was not coordinated or immediate, but scattered—individual landings along a shoreline that did not announce itself as destination, only as the end of exposure (DNCR, 2016). Of its 150 passengers and 37 crew, only 59 survived (Falk, 2025).
The wreck remains offshore, beyond the shifting bars where waves no longer break it apart in the same way. It does not return to the surface in the way some grounded vessels do. It settles instead into deeper water, where structure changes more slowly and remains largely out of view.
The shoreline holds something else. Not the wreck itself, but the moment when motion without direction became arrival. A place where drifting resolved, not into discovery, but into contact—where water gave way to land, and movement, at last, found its edge.
Want to learn more about the Pulaski? Listen to a podcast from Shipwrecks and Seadogs about its history.
War Along the Inlets: New River
Blockade runner, Teaser, near Fort Monroe, Virginia, is an example of the blockade runners along our coastline. | Photo credit: MPI/Getty Images
During the Civil War, this coastline was not only a place of navigation, but of control.
New River Inlet, leading inland toward what is now Jacksonville, served as a potential access point between coastal waters and interior routes. Union naval forces patrolled the coast as part of a broader blockade, attempting to restrict movement of goods and supplies, while Confederate forces relied on smaller vessels and local knowledge of the waterways to move through the system (Browning, 2002; Stick, 1990).
For any vessel entering New River, the challenge would have been familiar.
The inlet itself was shallow and shifting, defined by sandbars that changed position with storms and tides. Navigation required timing, local knowledge, and an ability to read water that did not present itself clearly from offshore (Riggs & Ames, 2003).
Unlike some of the more widely known Civil War wreck sites along the North Carolina coast, there is no clear record of a major vessel sinking within New River itself. But the absence of a wreck does not mean the absence of difficulty. The conditions that prevent passage do not always leave a visible record. Any ship moving through that inlet would have encountered the same conditions that shape it today.
Shallow approaches, moving sand, and water that changes faster than it can be mapped. The difference is not in the coastline, only in the ships that attempt to pass through it.
Farther south along this same stretch of coast lies the Cape Fear Civil War Shipwreck District, a cluster of documented wreck sites near the approaches to the Cape Fear River and the port of Wilmington. These wrecks, concentrated off Brunswick, New Hanover, and parts of Pender County, represent vessels involved in the Confederate blockade-running trade. Ships attempting to slip past Union naval patrols carried cargo that ranged from military supplies and weapons to manufactured goods and cloth desperately needed in the South. Many were narrow, fast steamers built with shallow drafts and reinforced hulls designed to move quickly through inlets and across shoals. Their loss was not incidental, but patterned—occurring in a region where shifting channels, shallow bars, and the pressure of pursuit converged. Archaeological surveys of this coastline describe a dense concentration of wreck sites associated with these movements, forming one of the most significant Civil War maritime landscapes along the Atlantic seaboard (North Carolina Office of State Archaeology, n.d.; Browning, 2002; Hall, 2004).
Working Maritime Coast: William H. Sumner (1919)
The William H. Sumner circa 1919 and what remains today. | Photo credits: Cape Fear Museum of History and Science (left); A. Mitchell (right)
In 1919, the schooner William H. Sumner approached this same coastline carrying cargo northward. The conditions it encountered were not new. The channel it relied on had shifted beyond what the vessel could safely cross.
The grounding was not violent, but it was final.
Accounts from the time suggest that by the final days of the voyage, conditions aboard the vessel had already begun to shift. Rations had reportedly run low, and attention moved away from navigation. In the hours after the grounding, the captain was found dead in his cabin from a gunshot wound, and the ship’s mate was later charged with mutiny and murder. Testimony conflicted. Some described tension among the crew, others described familiarity and routine. The trial that followed ended without resolution, leaving the cause of the captain’s death uncertain (North Carolina Shipwrecks, n.d.; Wrightsville Beach Magazine, 2015).
Once the hull met the sandbar near Topsail Inlet, where multiple vessels have grounded over centuries of shifting channels, wave energy began to work against it, gradually breaking the structure apart (Riggs & Ames, 2003; Pilkey, 1998; Hall, 2004). Salvage efforts removed what could be taken. What remained did not leave with it. It settled into the shoreline system, where it was taken in and buried beneath moving sand (Riggs & Ames, 2003; Pilkey, 1998).
Over time, and then at intervals shaped by storms, it appeared again.
Storms and low tides continue to strip away the sand that covers portions of the wreck, exposing curved timbers that seem, for a short time, to return. These exposures are often described as discoveries, but the structure has been present throughout, shifting between visibility and concealment as sediment moves across it (Riggs & Ames, 2003). When these timbers reappear, they are not simply objects to be collected. As registered historic shipwreck remains, they are protected under state law, and removing or disturbing them is prohibited, preserving both the structure and the record it represents (ABC45 News, 2024).
The wreck does not travel. The coastline moves around it.
Wrecks Beyond the Shoals
Farther offshore, beyond the shifting bars and inlets, the nature of shipwrecks begins to change.
In deeper water, vessels are less likely to run aground and more likely to be lost through damage that begins within the ship itself—fire, structural failure, or, in the case of the North Carolina coast during World War II, torpedo strikes from German U-boats operating just off the continental shelf (Hoyt et al., 2021; Blair, 2000).
By the time of World War II, this stretch of coastline was already part of what is often called the “Graveyard of the Atlantic,” a name shaped by centuries of shipwrecks driven by storms, shifting shoals, strong currents, and difficult navigation along the North Carolina coast (Stick, 1990; Hoyt et al., 2021). The war did not create this pattern, but added to it, concentrating losses offshore as vessels were targeted in transit. Tankers and cargo ships moving along the eastern seaboard were struck at sea, often at night, their hulls breached below the waterline as they traveled.
The process is different. Instead of grounding, there is descent.
A vessel lists, loses buoyancy, and slips beneath the surface, settling onto the seafloor often in a more intact form than those broken apart in shallow surf. Once compromised, these ships took on water rapidly and sank into deeper channels where the seabed lay far below the reach of waves (Wells & McNinch, 1991).
In some cases, even when a wreck is located, its identity remains uncertain. Historical comparisons of structure, propulsion, and location have led to tentative identifications—such as the possible association of certain offshore remains with Civil War–era blockade runners—but these connections are not always definitive and may remain unresolved despite decades of study (Stallman, 2011).
Off the coast of Onslow County, these deeper wrecks remain present, though rarely visible from shore.These wrecks are not isolated features, but part of a broader offshore field of structure, scattered across the continental shelf. Some have been mapped and studied, while others remain only partially defined, their forms intact below the reach of waves. What defines them is not their visibility, but their persistence—structures that remain in place long after the events that created them, shaping the surrounding environment in ways that are not immediately seen.
Storm Without Shore: Normannia (1924)
The Normannia | Photo credit: Library of Congress
Vessels in deeper water faced a different kind of exposure than those nearer to the shoals.
In 1924, the Normannia foundered during a storm offshore. The forces at work were not those of shifting shoals, but of sustained wind, wave height, and structural stress. Far from the influence of the coastline’s sandbars, the vessel did not run aground. It remained in open water until the structure failed (Gentile, 1992).
As the hull lost integrity, water entered faster than it could be expelled. Stability gave way. The vessel listed, settled, and slipped beneath the surface (Gentile, 1992).
There was no bar to hold it, no shoreline to break it apart—only depth to receive it.
March 1942: A Concentrated Loss Offshore
In March of 1942, multiple vessels moving along this coastline were struck within a matter of days, part of a concentrated period of U-boat activity along the North Carolina coast.
Other vessels from this same period reflect the intensity of offshore loss during the war. The tanker Naeco, more than 400 feet in length, was struck by a torpedo from U-124 and broke apart before sinking, its bow and stern sections settling separately on the seafloor miles apart. The tanker Esso Nashville was also torpedoed that year; its bow section sank offshore while the stern remained afloat long enough to be recovered, later refitted and returned to service. When the tanker John D. Gill was struck by U-158, where 23 were lost and 26 survived, burning oil ignited on the water, creating a fire visible from shore, extending the event into the night sky itself (Taylor, 2025).
The John D. Gill (left) and the Naeco (left) | Photo credits: G. Gentile (left) and Marines Museum {right}
These vessels did not meet the coast through sand. They were lost to force applied below the waterline, their structures descending into deeper channels beyond the reach of waves (Hoyt et al., 2021; Blair, 2000; Wells & McNinch, 1991).
Over time, these wrecks become stable structures in deeper water, less influenced by shifting sand and more by currents, corrosion, and biological growth. They are still part of the same coastal system, but they are shaped by depth rather than motion (Paxton et al., 2023).
Likely a picture of the Esso Nashville, due to its stern configuration (left) and the starboard and bow anchor of the Esso Nashville (right) | Photo credits: G. Gentile (left) and P. Hudy (right)
War Along the Shore: Observation Without Contact
While vessels were being lost offshore, the coastline itself became part of the wartime landscape.
Along Topsail Island, a series of observation towers were constructed as part of Operation Bumblebee, where military personnel tracked missile tests and coastal activity from elevated positions above the shoreline. From these towers, the ocean was not empty space but an active field—ships moving along the horizon, and at times, evidence of conflict unfolding beyond direct reach (Island Life NC, 2025).
The coastline did not receive these wrecks.
But it witnessed them.
Collision in Transit: Cassimir (1942)
Not all vessels lost during this period were the result of attack.
The Cassimir, built in 1920, sank in 1942 following a collision with the freighter Lara. The loss occurred offshore, in deeper water, where the structure did not ground but instead descended to the seafloor. Its presence reflects a different kind of vulnerability—navigation intersecting with proximity rather than conflict or storm (Gentile, 1992).
The outcome, however, remains consistent.
The vessel did not meet sand.
It entered depth.
The Cassimer circa 1920 (left) and its anchor at the wreck site (right) | Photo credits: G. Gentile (left) and P. Hudy (right)
Modern Abandoned Vessels: Those That Become Something Else
Along the coast today, abandoned vessels follow a similar trajectory, though their timeline is still unfolding. Shrimp boats grounded on shoals or left after mechanical failure may remain in place for years, shifting slightly with storms but never fully leaving.
Abandoned shrimp vessel in Stump Sound | Photo credit: L. Caldwell
During that time, they begin to change.
Osprey use the elevated structure for nesting. Barnacles attach to submerged surfaces. Fish gather beneath the hull where shade and form offer protection. In a sandy coastal system, any stable structure creates opportunities for life to organize around it.
But what develops on these vessels depends strongly on where they come to rest.
When a boat grounds on a shoal or nearshore bar, the surrounding environment remains in constant motion. Waves pass through the structure with each tide cycle, sand migrates around the hull, and storms periodically bury or expose different portions of the wreck. Habitat in these places is shaped by disturbance. The organisms that establish themselves must tolerate shifting sediment, abrasion, and periodic exposure to air.
The first arrivals appear quickly. Within weeks, thin microbial films and algae coat the surfaces of exposed wood, steel, or fiberglass. Barnacles and oysters follow, attaching themselves wherever water continues to move across the hull. Mussels cluster along beams and ribs where currents deliver suspended food. Small fish begin to gather in the shadows beneath the structure—pinfish, blennies, and juvenile black sea bass slipping into crevices created by broken ribs or propeller shafts. Sheepshead move in to feed on barnacles and shellfish, while blue crabs and shrimp occupy pockets where sand collects between fragments.
Over time, the wreck becomes less a single object than a patch of structure embedded in the moving beach system. Sandbars migrate across it. Portions disappear beneath sediment, only to reappear after storms. Habitat here is temporary and episodic, shaped by the same forces that buried the vessel in the first place.
Farther offshore, the process unfolds differently.
When a vessel sinks into deeper water beyond the reach of breaking waves, the surrounding seabed is more stable and the structure often settles largely intact. Steel hulls, decks, and internal compartments create vertical relief in a landscape otherwise dominated by sand. Hard surfaces are scarce along this portion of the continental shelf, and life responds quickly when they appear.
Shipwrecks in North Carolina reflect rich maritime history and are home to a diversity of marine life. | Photo credit: T. Casserley, NOAA.
Within weeks, bacterial films coat the structure. Barnacles, hydroids, and tube worms attach soon after, followed by sponges, anemones, and soft corals that require firm substrate to establish. Over months and years, these organisms layer over one another, transforming the wreck from bare metal or timber into something resembling natural reef.
Within weeks, bacterial films coat the structure. Barnacles, hydroids, and tube worms attach soon after, followed by sponges, anemones, and soft corals that require firm substrate to establish. Over months and years, these organisms layer over one another, transforming the wreck from bare metal or timber into something resembling natural reef.
Fish respond just as quickly. Small schooling species—tomtate, baitfish, and spadefish—begin to circle the structure, drawn to shelter and feeding opportunities. As prey accumulates, larger predators follow. Snapper and grouper hold close to the hull, amberjack patrol the upper water column, and barracuda and sharks move through the surrounding water where prey becomes concentrated (Bohnsack & Sutherland, 1985; Paxton et al., 2023).
In waters off North Carolina, these offshore wrecks are also known for attracting one of the coast’s most recognizable predators. Sand tiger sharks often patrol the edges of wreck sites along the continental shelf, moving slowly through the water column where schools of fish gather around the structure (Castro, 2011; Paxton et al., 2023). Unlike fast-moving pelagic sharks, sand tigers tend to hover deliberately near reefs and wrecks, conserving energy while watching the dense concentrations of prey that form there (Castro, 2011). Divers frequently encounter them circling shipwrecks in loose groups, their presence marking the final stage of a habitat that began as bare metal or timber settling onto an otherwise sandy seafloor (Paxton et al., 2023).
Over decades, these deeper wrecks can support complex communities that persist long after the vessel itself begins to corrode. The structure weakens slowly, but before it collapses it may host a dense network of organisms comparable to natural hard-bottom reefs.
A sand tiger shark patrols the SS Tarpon shipwreck. Scientists believe these sharks use shipwrecks as “rest stops” on their long migratory path from New England to Florida and can be beneficial for their conservation. | Photo credit: NOAA
Artificial Reefs and Intentional Sinking
Recognizing this ecological potential, many coastal states—including North Carolina—have intentionally sunk vessels as part of artificial reef programs. Before sinking, ships are stripped of fuels, wiring, plastics, and other materials that could pollute surrounding waters. What remains is the structural framework: steel decks, beams, and bulkheads that provide vertical complexity.
Once placed on the seafloor, these vessels follow much the same ecological trajectory as accidental wrecks, often more quickly because the structure is intact and positioned on a stable bottom. Fish communities can begin forming within months, with predators arriving as prey species establish themselves (Bohnsack & Sutherland, 1985; Pickering & Whitmarsh, 1997).
The resulting reef does more than host new organisms. It changes the surrounding environment. Currents interacting with the hull create eddies that trap plankton and organic material. Sand that once held little structure becomes a landmark on the seafloor where life gathers.
But the distinction between prepared artificial reefs and abandoned vessels remains important. Ships intentionally sunk for reef programs are cleaned to reduce contamination, while vessels left to deteriorate in place undergo corrosion and material breakdown that can introduce contaminants into surrounding waters as their structure degrades (MacLeod, 2006).
Even so, the ecological impulse is the same. Wherever the coast receives structure, life organizes around it.
In some cases, this ecological response has led coastal managers to intentionally place vessels on the seafloor as artificial reefs, recognizing that stable structure can support complex marine communities. Along this coastline, however, similar structures are not treated in the same way. Some wrecks are preserved as part of the historical record, protected because they represent events that cannot be reconstructed once disturbed. Others are managed as hazards, their removal shaped by environmental risk and navigational safety. Still others are placed deliberately, prepared and sunk to provide habitat without the long-term effects of deterioration. What appears similar from the surface carries different meanings depending on how it is understood—as a record, a risk, or a design.
Along the Topsail Island coast, vessels have been intentionally placed on the seafloor as part of North Carolina’s artificial reef program, where cleaned ships are sunk to create habitat for fish and other marine life while providing new structure in otherwise sandy environments (Report, 2024).
What the Coast Does With What We Leave Behind
Shipwrecks are often described as endings, but along the Onslow coast they function more as transitions.
A vessel moves through stages. It carries people and cargo, meets a coastline that does not hold still, and becomes structure. That structure gathers life, shifts within the movement of sand, and settles into memory. The boundaries between these stages are not fixed. They move with the same currents and tides that shape the shoreline itself.
Nothing here is entirely lost. It is redistributed.
Wood, iron, fiberglass, and story all enter the same system, resurfacing when conditions allow. What appears after a storm is not new, but newly visible—a brief alignment of movement and exposure that allows what has long been present to be seen again.
The beach does not keep everything in sight. But it keeps everything, waiting for the moment the sand moves and the past becomes visible again.
The surface returns to quiet. The system does not. | Photo credit: A. Mitchell
References
Blair, C. (2000). Hitler’s U-boat war: The hunted, 1942-1945. Modern Library.
Hoyt, J. C., Bright, J. C., Hoffman, W., Carrier, B., Marx, D., Richards, N., Sassorossi, W., Davis,
K., Wagner, J., & McCord, J. (2021). Battle of the Atlantic: A Catalog of Shipwrecks off North Carolina’s Coast from the Second World War (BOEM IA M10PG00048). BOEM’s Office of Renewable Energy Programs and NOAA’s Office of National Marine Sanctuaries. https://www.govinfo.gov/app/details/GOVPUB-I–b4c8d5485d6e8270384848d0e6d5efbc
Paxton, A. B., McGonigle, C., Damour, M., Holly, G., Caporaso, A., Campbell, P. B.,
Meyer-Kaiser, K. S., Hamdan, L. J., Mires, C. H., & Taylor, J. C. (2023). Shipwreck ecology: Understanding the function and processes from microbes to megafauna. BioScience, 74(1), 12-24. https://doi.org/10.1093/biosci/biad084
Pickering, H., & Whitmarsh, D. (1997). Artificial reefs and fisheries exploitation: A review of the ‘attraction versus production’ debate, the influence of design and its significance for policy. Fisheries Research, 31(1-2), 39-59. https://doi.org/10.1016/s0165-7836(97)00019-2
Pilkey, O. H. (1998). The North Carolina shore and its barrier islands: Restless ribbons of sand. Duke University Press.
Riggs, S. R., Cleary, W. J., & Snyder, S. W. (1995). Influence of inherited geologic framework on barrier shoreface morphology and dynamics. Marine Geology, 126(1-4), 213-234. https://doi.org/10.1016/0025-3227(95)00079-e
Shomette, D. G. (2008). The price of amity: Of wrecking, piracy, and the tragic loss of the 1750 Spanish treasure fleet. The Northern Mariner / Le marin du nord, 18(3-4), 25-48. https://doi.org/10.25071/2561-5467.354
Stallman, D. A. (2011). Echoes of topsail: Stories of the island’s past (3rd ed.). Carlisle Printing.
Stick, D. (1990). The Outer Banks of North Carolina, 1584-1958. The University of North Carolina Press.
Ward, I., Larcombe, P., & Veth, P. (1999). A new process-based model for wreck site formation. Journal of Archaeological Science, 26(5), 561-570. https://doi.org/10.1006/jasc.1998.0331
Wells, J. T., & McNinch, J. E. (1991). Role Of Inlet Dynamics In Scour And Burial Of Marine Artifacts In Energetic Coastal Settings. In Maritime heritage (65th ed., pp. 87-96). WIT Press. https://doi.org/10.2495/MH030081
Wilde-Ramsey, M. U., & Carnes-McNaughton, L. F. (2016). Blackbeard’s Queen Anne’s Revenge and Its French Connection. In Pieces of Eight: More Archaeology of Piracy (pp. 15-56). University Press of Florida.
Wilde-Ramsing, M. U., & Carnes-McNaughton, L. F. (2018). Blackbeard’s sunken prize: The 300-Year voyage of Queen Anne’s revenge. UNC Press Books.
A breath breaks the air first — a soft exhale that sounds almost human — and then a dorsal fin lifts from the channel like a line drawn through moving water. The tide is falling. Gulls hover over the seam where current tightens. Fishermen pause mid-cast because everyone knows the rhythm: if the dolphins are working the edge, the fish are already gathering.
These encounters feel spontaneous, but they are not accidents. The dolphins that surface beside our piers, marsh creeks, and inlets are not anonymous travelers passing through. Many bottlenose dolphins show long-term site fidelity and structured community patterns in estuarine systems, returning to the same places across years (Urian et al., 2009; Wells, 2014). To live on this shoreline is to share space with minds moving just below the surface — residents of the tidal edge.
Who they are: a coastal population
The dolphins most frequently seen along Onslow County’s waters are common bottlenose dolphins (Tursiops truncatus), a species whose “coastal” lives can look very different from “offshore” lives. Across the western North Atlantic, genetic studies show fine-scale population structure that can separate dolphins using nearshore coastal waters from dolphins using inshore estuarine waters (Rosel et al., 2009). More broadly, integrative work continues to support meaningful coastal vs offshore divergence in the region (Costa et al., 2022).
In estuaries, photo-identification research (matching dorsal-fin markings) repeatedly shows that bottlenose dolphins can form discrete social communities with limited spatial overlap — a pattern consistent with long-term residency and local familiarity (Urian et al., 2009). In practical terms, the dolphin a child watches from a dock in spring may be seen again the following winter, and again the next year: not a rumor, but a biological possibility supported by long-term studies of resident dolphins elsewhere on the coast (Wells, 2014).
Photo-identification doesn’t always rely solely on human matching of fin shapes; new tools such as machine learning are being developed to improve accuracy in identifying individual dolphins and whales in the wild. For example, researchers in Hawaii are using advanced algorithms to distinguish individuals from large photo libraries of dorsal fins. As technology improves, methods like photo-ID only get more reliable — which means studies of habitat overlap and seasonal return become more precise over time.
An inside look at how scientists “read” dorsal fin shapes and markings to track the same dolphins over time.
Reading the geometry of the estuary
Dolphins do not simply occupy estuaries; they interpret them.
Tidal channels function as moving architecture. Falling tides compress fish schools toward narrowing exits. Sandbars redirect flow into faster seams. Marsh edges trap prey against shallow gradients. Dolphins exploit these features with precision, repeatedly targeting conditions that make prey capture more efficient (Barros & Wells, 1998; Torres & Read, 2009).
This is one reason dolphins so often appear where the water “looks alive” — at convergence lines, inlet throats, and channel bends. In Florida Bay, for example, foraging tactics are mapped onto habitat features that define where dolphins have spent their time, thus turning behavior into geography (Torres & Read, 2009). What seems like play from shore can be highly strategic predation.
Bottlenose dolphins breaching off Seaview Pier, N. Topsail Beach, North Carolina. The arc of the body and column spray reflect the mechanics of propulsion – force directed through the tail, momentum carried into the air. | Photo credit: Howard Crumpler Photography, 2026
Reader Question:
Why do dolphins seem more active on rainy or overcast days?
Weather, light, and the illusion of play
You may notice that dolphins seem especially active on overcast or rainy days — surfacing more frequently, breaching, or moving in tight arcs through wind-rippled water. It can look like preference, even mood. But dolphins are responding less to cloud cover than to what cloud cover does to the water.
When the sky darkens, baitfish don’t stay arranged the same way. They may bunch together or rise toward the surface. For a predator already working those upper layers, that shift can make hunting more efficient (Benoit-Bird & Au, 2003). Wind and rain can also stir the surface and cloud the water, changing who sees whom first (De Robertis et al., 2003).
There is also a perceptual component. Overcast skies reduce glare, making dorsal fins and splashes easier for human observers to detect. Wind-textured water highlights movement. What appears to be “more play” may sometimes be improved visibility — a reminder that observer experience and animal behavior are not always the same phenomenon.
In short, dolphins are responding to ecological conditions. The weather alters the water; the water alters the fish.
Two bottlenose dolphins break the surface beneath the gray horizon off Surf City, North Carolina. Overcast light and wind-roughened water can change how fish move – and how easily we notice the dolphins following them. | Photo credit: Johnny Provost, Jr., 2025
Communication and social intelligence
Bottlenose dolphins have been studied for decades not just because they are charismatic, but because their social lives depend on constant communication in a shifting, three-dimensional world. One of the strongest findings to emerge from that research is the existence of signature whistles — individually distinctive call types that function as learned identity signals, something very much like the individual name a dolphin goes by within its community (Janik & Sayigh, 2013).
Social learning runs just as deep. Some dolphin foraging habits spread from one animal to another rather than through genetics — passed along socially, a rare pattern among nonhuman species (Krützen et al., 2005). Mothers and calves stay together for years, giving calves time to learn not just how to hunt, but where — which channels to follow, which bends of water hold fish (Wells, 2014).
In some populations elsewhere in the world, dolphins even use tools — carrying marine sponges on their rostrums while foraging or trapping fish inside empty shells — behaviors that are socially learned and culturally transmitted (Krützen et al., 2005).
That learning shapes how dolphins fit into the estuary. In many tidal systems they sit near the top of the local food web, influencing the fish communities beneath them. Yet beyond those protected waters, they are not beyond risk. Large sharks prey on dolphins, placing them within a broader coastal hierarchy where even predators can become prey (Heithaus, 2001). The role shifts with scale. The ecology remains layered.
Two bottlenose dolphins surfacing together off Seaview Pier, N. Topsail Beach, North Carolina. Close positioning and timing are hallmarks of the complex social bonds that define dolphin societies. | Photo credit: Howard Crumpler Photography, 2026
Dolphins are not guardians
Popular culture has assigned dolphins a role they never chose: protector. People repeat a comforting shoreline myth — “If you’re scared of sharks, find the dolphins; they’ll protect you.” But that story is not grounded in how dolphins behave in the wild.
Bottlenose dolphins are powerful predators. They compete, establish dominance hierarchies, and can deliver forceful blows when defending calves or asserting space. Dolphin–shark interactions occur, but they are not “rescue missions” staged for humans; they are ecological encounters shaped by risk, competition, and opportunity (Heithaus, 2001).
Wild dolphins are also capable of injuring people. Research examining human–dolphin interactions show that close approaches — and especially feeding wild dolphins — increase the likelihood of risky contact and harmful outcomes for both dolphins and people (Cunningham-Smith et al., 2006; Vail, 2016). Over time, those interactions leave visible consequences. Long-term data from Sarasota Bay show that dolphins who have learned to associate people with food are more likely to carry injuries linked to boats and fishing gear (Christiansen et al., 2016).
The danger is not that dolphins are “evil.” The danger is assuming they share human intentions.
Swimming near a pod does not create a protective shield. Dolphins are not lifeguards. They are wild animals navigating their own priorities in a shared environment. Respecting that boundary is what allows coexistence.
A bottlenose dolphin pursuing prey near a recreational vessel in a waterway in Surf City, North Carolina. Foraging behavior can bring dolphins into close proximity with boats – not as companions, but as active predators focused on fish. | Video credit: Cynthia Dirosse, 2024
Winter dolphins
A persistent assumption is that dolphins vanish when the water cools. In reality, seasonal distribution can be more nuanced — changing with prey, temperature, and coastal movement patterns rather than following a simple on/off presence.
Along the mid-Atlantic coast, research shows that bottlenose dolphins shift their movements with the seasons, appearing in different areas at different times of year (Torres et al., 2005). Studies focused on estuarine dolphins in southern North Carolina document similar seasonal patterns closer to home (Silva et al., 2020). From shore, those changes can look like disappearance. But winter quiet does not always mean absence. It may simply mean dolphins are working deeper channels or less visible pathways beyond the easy reach of our eyes.
The estuary in winter is quieter, but not empty.
Dorsal fins in winter light off Surf City, North Carolina. Dolphins may appear less active this time of year, but changes in light, water depth, and travel corridors often influence what we notice from shore. | Photo credit: Surf City Parks, Recreation, and Tourism, 2017
Living beside them
Living near dolphins is a privilege — and it places us within the same waters they navigate. Vessel traffic, fishing gear, and repeated close approaches can shape the lives of animals that live for decades and raise calves slowly (Wells, 2014). Studies of dolphins that have been fed or closely approached by people show that these interactions can shift behavior, making dolphins more likely to approach boats and increasing the risk of injury and conflict (Vail, 2016). Distance, in that sense, preserves the patterns people come to watch.
The presence of dolphins is not guaranteed. It is a sign that the system still functions — prey, water quality, shoreline structure, and the complex social knowledge dolphins carry from year to year. As long-lived predators near the top of the food web, they are indicator species, reflecting the condition of the waters they inhabit — estuary, inlet, and nearshore coast alike.
And so when a dorsal fin rises beyond the channel markers, it means more than a moment of spectacle. It means the currents are still working, the fish are still moving, and the layered relationships that shape this shoreline are still holding.
There is always more to learn about dolphins than fits in a single post. For those who’d like to go further, this episode of the All Creatures Podcast offers a thoughtful exploration of their biology and behavior.
References
Barros, N. B., Wells, R. S., & Barros, N. B. (1998). Prey and feeding patterns of resident bottlenose dolphins (Tursiops truncatus) in Sarasota Bay, Florida. Journal of Mammalogy, 79(3), 1045. https://doi.org/10.2307/1383114
Benoit-Bird, K. J., & Au, W. W. (2003). Prey dynamics affect foraging by a pelagic predator (Stenella longirostris) over a range of spatial and temporal scales. Behavioral Ecology and Sociobiology, 53(6), 364-373. https://doi.org/10.1007/s00265-003-0585-4
Christiansen, F., McHugh, K. A., Bejder, L., Siegal, E. M., Lusseau, D., McCabe, E. B., Lovewell, G., & Wells, R. S. (2016). Food provisioning increases the risk of injury in a long-lived marine top predator. Royal Society Open Science, 3(12), 160560. https://doi.org/10.1098/rsos.160560
Costa, A. P., Mcfee, W., Wilcox, L. A., Archer, F. I., & Rosel, P. E. (2022). The common bottlenose dolphin (Tursiops truncatus) ecotypes of the western North Atlantic revisited: An integrative taxonomic investigation supports the presence of distinct species. Zoological Journal of the Linnean Society, 196(4), 1608-1636. https://doi.org/10.1093/zoolinnean/zlac025
Cunningham-Smith, P., Colbert, D. E., Wells, R. S., & Speakman, T. (2006). Evaluation of human interactions with a provisioned wild bottlenose dolphin (<I>Tursiops truncatus</I>) near Sarasota Bay, Florida, and efforts to curtail the interactions. Aquatic Mammals, 32(3), 346-356. https://doi.org/10.1578/am.32.3.2006.346
De Robertis, A., Ryer, C. H., Veloza, A., & Brodeur, R. D. (2003). Differential effects of turbidity on prey consumption of piscivorous and planktivorous fish. Canadian Journal of Fisheries and Aquatic Sciences, 60(12), 1517-1526. https://doi.org/10.1139/f03-123
Heithaus, M. R. (2001). Shark attacks on bottlenose dolphins (TURSIOPS ADUNCUS) in Shark Bay, Western Australia: Attack rate, bite scar frequencies, and attack seasonality. Marine Mammal Science, 17(3), 526-539. https://doi.org/10.1111/j.1748-7692.2001.tb01002.x
Janik, V. M., & Sayigh, L. S. (2013). Communication in bottlenose dolphins: 50 years of signature whistle research. Journal of Comparative Physiology A, 199(6), 479-489. https://doi.org/10.1007/s00359-013-0817-7
Krützen, M., Mann, J., Heithaus, M. R., Connor, R. C., Bejder, L., & Sherwin, W. B. (2005). Cultural transmission of tool use in bottlenose dolphins. Proceedings of the National Academy of Sciences, 102(25), 8939-8943. https://doi.org/10.1073/pnas.0500232102
Rosel, P. E., Hansen, L., & Hohn, A. A. (2009). Restricted dispersal in a continuously distributed marine species: Common bottlenose dolphinsTursiops truncatusin coastal waters of the western North Atlantic. Molecular Ecology, 18(24), 5030-5045. https://doi.org/10.1111/j.1365-294x.2009.04413.x
Silva, D. (2020). Abundance and seasonal distribution of the southern North Carolina estuarine system stock (USA) of common bottlenose dolphins (Tursiops truncatus). IWC Journal of Cetacean Research and Management, 21(1), 33-43. https://doi.org/10.47536/jcrm.v21i1.175
Torres, L. G., McLellan, W. A., Meagher, E., & Pabst, D. A. (2023). Seasonal distribution and relative abundance of bottlenose dolphins, Tursiops truncatus, along the US Mid-Atlantic coast. J. Cetacean Res. Manage, 7(2), 153-161. https://doi.org/10.47536/jcrm.v7i2.748
Torres, L. G., & Read, A. J. (2009). Where to catch a fish? The influence of foraging tactics on the ecology of bottlenose dolphins (Tursiops truncatus) in Florida Bay, Florida. Marine Mammal Science, 25(4), 797-815. https://doi.org/10.1111/j.1748-7692.2009.00297.x
Urian, K. W., Hofmann, S., Wells, R. S., & Read, A. J. (2009). Fine‐scale population structure of bottlenose dolphins (Tursiops truncatus) in Tampa Bay, Florida. Marine Mammal Science, 25(3), 619-638. https://doi.org/10.1111/j.1748-7692.2009.00284.x
Vail, C. S. (2016). An overview of increasing incidents of bottlenose dolphin harassment in the Gulf of Mexico and possible solutions. Frontiers in Marine Science, 3. https://doi.org/10.3389/fmars.2016.00110
Wells, R. S. (2013). Social structure and life history of bottlenose dolphins near Sarasota Bay, Florida: Insights from four decades and five generations. Primatology Monographs, 149-172.
A microscopic epic of drift, decision, and devotion
On a winter walk along a pier in Surf City, the boards are bleached pale by sun and salt. Wind threads through the pilings. Gulls cry over gray water. At your feet, on a beam that has known decades of tides, something clings.
It is no bigger than a fingernail—chalky white, ridged like a tiny volcano. Along this coast, it is often an ivory barnacle—Amphibalanus eburneus—one of the small architects that quietly carpet pilings, docks, and seawalls from Topsail Sound to the Cape Fear. You could scrape it away with the edge of a shell. You probably have, absentmindedly, a hundred times.
But this barnacle is not debris. It is a biography written in calcium.
It began as a drifting dot—an invisible life in a moving sea. It crossed currents. It tasted the chemistry of places. And then, once, it chose.
The choice was final.
Barnacles are among the few animals on Earth that get exactly one chance to decide where they will live. No revisions. No migrations. No second homes. The place where a barnacle settles becomes the place where it will eat, grow, reproduce, and die. Its entire life collapses into a single coordinate on the map of the shore.
To understand a barnacle is to understand what it means to commit.
Ivory barnacles cling to a rock | Photo credit: Ken-ichi Ueda
Drift
A barnacle’s life begins in motion.
After fertilization, barnacle embryos hatch into nauplius larvae—tiny, triangular forms equipped with beating appendages and a simple eye (Anderson, 1994). They rise into the plankton, where they may drift for days to weeks, feeding and growing as tides and currents carry them outward (Chen et al., 2014).
The first larval stage of a barnacle, called a nauplius, is free-swimming and distinguished by a set of “horns.” | Photo credit: Robert Bachand
They are not aimless. Even at this scale, nauplii respond to light, salinity, and gravity. They migrate vertically through the water column, riding layers of current like conveyor belts. Their world is vast and borderless—and lethal.
Most barnacles die here.
Nauplii are eaten by copepods, jellyfish, fish larvae, and filter-feeding invertebrates. Each pulse of water is a gauntlet. Survival depends on number: millions released so that a few may reach shore.
After several molts, the nauplius enters its final larval form: the cyprid.
A late larval barnacle stage, the cyprid, has a bivalved shell of chitin and glands in its first antennae that are used to cement itself permanently to a hard substrate. | Photo credit: Robert Bachand
This is no longer a feeding animal. It is a vessel of stored energy, built for a single task—finding a place to live (Aldred & Clare, 2008).
The cyprid does not eat.
A clock begins.
Much of what we know about this hidden stage comes from decades of work on a close coastal relative, the striped barnacle – Amphibalanus amphitrite—a warm-water barnacle that clings to pilings and boat hulls worldwide, and whose larvae have become a window into how barnacles read the sea.
The striped barnacle (Amphibalanus amphitrite) is a globally distributed, non-native barnacle species that can spread via biofouling. In North Carolina waters it may occur outside its historical native range, but it isn’t widely recognized as a documented invasive species causing major ecological disruption. | Photo Credit: South Australia Marine Lab
The Narrow Window
Now the barnacle is no longer drifting blindly. It swims with intent. The cyprid probes surfaces with specialized antennules, “tasting” the chemistry of rock, wood, shell, and steel. It detects microbial biofilms—thin living skins that signal a surface has been stable long enough to support life (Qian et al., 2007). It senses the presence of other barnacles. It avoids surfaces that feel wrong.
This sensory world evolved in seas that were chemically simpler.
Today, cyprids swim through waters laced with heavy metals, hydrocarbons, microplastics, antifouling compounds, and nutrient-driven microbial shifts. These pollutants alter biofilms, mask settlement cues, and interfere with larval sensory systems. What once read clearly as “home” now arrives as static.
In degraded waters, cyprids often hesitate. They probe and retreat. They circle without committing.
But the clock does not pause.
Depending on species and temperature, a cyprid has only days to a few weeks before its stored energy is exhausted (Aldred & Clare, 2008). Each hour of searching burns fuel. When reserves fall too low, three futures unfold.
Some larvae simply die in the plankton and sink.
Some make a desperate choice—cementing themselves to marginal or unstable surfaces.
Others respond to distorted cues and settle where survival is unlikely.
This is not a failure of instinct. It is a mismatch between ancient sensory logic and a changed sea.
Long before we notice a shoreline growing quieter, its future has already thinned in the plankton.
When the answer is yes, the barnacle performs one of the most irreversible acts in the animal kingdom.
It flips upside down.
Using its antennules, the cyprid secretes a permanent biological cement and glues its head to the surface (Kamino, 2016). This adhesive—among the strongest natural glues known—binds underwater to stone, metal, and polymer. Once cured, it cannot be undone.
There is no “testing.” No trial period.
This is the end of motion.
Within hours, the cyprid undergoes a radical metamorphosis. Its eyes degenerate. Its swimming limbs are restructured into feathery feeding appendages called cirri. Its body reorganizes around a new axis—rooted instead of free (Høeg & Møller, 2006).
The barnacle becomes architecture.
Many do not survive even this. Newly settled juveniles are grazed by small fish and invertebrates. Waves scrape them away before cement fully cures. The shoreline is littered with choices that did not last.
Those that remain begin to build something larger than themselves.
A Life Built Around the Tide
Most animals grow by addition. Barnacles grow by reinvention.
Shell plates rise around soft tissue, forming a fortress against wave impact, desiccation, and predation. Inside, muscles and organs reorganize to support a life of rhythmic feeding.
When submerged, the barnacle opens its opercular plates and unfurls its cirri—six pairs of jointed limbs that sweep the water in steady arcs. Each beat captures phytoplankton, detritus, and microcrustaceans (Southward, 2008).
Metabolism slows. Heat and salt concentrate. Time folds inward. Some intertidal barnacles endure body temperatures exceeding 40°C (104°F) and prolonged oxygen deprivation (Harley, 2008). They wait for the sea to return.
Each tide is both a threat and nourishment.
Anatomy of a barnacle. | Photo Credit: AnimalFact.com
Time in Shell
Barnacles record time the way trees do.
Their shells grow in increments, forming visible growth bands that reflect seasonal cycles and environmental stress (Crisp, 1989). Storms leave signatures. Cold winters slow deposition. Productive summers thicken walls.
A barnacle on a piling may live five, ten, even twenty years (Southward, 2008). It will experience thousands of tides, hundreds of storms, and uncountable shifts in salinity and temperature—without ever moving.
Where foraminifera archive ancient seas in sediment, barnacles archive living shorelines in calcium.
Barnacles occupy one of the most punishing habitats on Earth: the intertidal zone.
Here, organisms must withstand:
Wave forces exceeding hurricane winds
Repeated drying and rehydration
Rapid temperature swings
Salinity changes from rain and evaporation
Intense ultraviolet exposure
Few animals can survive here. Barnacles not only survive—they structure the place.
Every barnacle on this shore is the consequence of a single larval decision made weeks earlier in open water.
They stabilize surfaces. They retain moisture. They create crevices for algae, worms, snails, and juvenile crustaceans. They shape temperature gradients and water flow. They turn bare rock into habitat.
When settlement falters—when larvae cannot read the shore or run out of time—the architecture of the coast changes.
Bare rock expands. Algal communities shift. Grazers lose shelter. Predators lose prey. The intertidal simplifies.
A piling with fewer barnacles is not merely cleaner. It is quieter. Biologically poorer and less layered.
The Lesson in Shell
Return now to that single barnacle on the pier.
It has no eyes. It has never seen the ocean. It will never know the gull overhead or the human who pauses above it. And yet it has shaped its entire existence around this exact sliver of coast.
It did not choose perfectly.
Some barnacles settle too high and starve. Some attach where sand scours them away. Some cement themselves beside competitors that outgrow and smother them.
There is no guarantee.
Only the act of choosing.
In a world that prizes movement, flexibility, and endless revision, the barnacle offers a quieter philosophy:
At some point, life must become a place.
To belong is not to drift forever. It is to accept exposure. To endure storms. To open when the tide allows. To grow, layer by layer, into the shape of your ground.
Every barnacle on this coast is a monument to a single irreversible decision.
And the sea is full of them.
Bay barnacle, Amphibalanus improvisus, on a rock in the New River | Photo credit: Alina Michele, iNaturalist, 2022
References
Aldred, N., & Clare, A. S. (2008). The adhesive strategies of cyprids and development of barnacle-resistant marine coatings. Biofouling, 24(5), 351-363. https://doi.org/10.1080/08927010802256117
Anderson, D. T. (1994). Barnacles: Structure, function, development and evolution (1st ed.). Springer Dordrecht.
Chen, Z., Zhang, H., Wang, H., Matsumura, K., Wong, Y. H., Ravasi, T., & Qian, P. (2014). Quantitative Proteomics study of larval settlement in the barnacle balanus Amphitrite. PLoS ONE, 9(2), e88744. https://doi.org/10.1371/journal.pone.0088744
Crisp, D. J. (1989). Tidally deposited bands in shells of barnacles and molluscs. Origin, Evolution, and Modern Aspects of Biomineralization in Plants and Animals, 103-124. https://doi.org/10.1007/978-1-4757-6114-6_8
Harley, C. D. (2008). Tidal dynamics, topographic orientation, and temperature-mediated mass mortalities on rocky shores. Marine Ecology Progress Series, 371, 37-46. https://doi.org/10.3354/meps07711
Høeg, J. T., & Møller, O. S. (2006). When similar beginnings lead to different ends: Constraints and diversity in cirripede larval development. Invertebrate Reproduction & Development, 49(3), 125-142. https://doi.org/10.1080/07924259.2006.9652204
Qian, P., Lau, S. C., Dahms, H., Dobretsov, S., & Harder, T. (2007). Marine Biofilms as mediators of colonization by marine Macroorganisms: Implications for antifouling and aquaculture. Marine Biotechnology, 9(4), 399-410. https://doi.org/10.1007/s10126-007-9001-9
Southward, A. J. (2008). Barnacles: Keys and notes for the identification of British species. Field Studies Council. Yu, S., & Chan, B. K. (2020). Intergenerational microplastics impact the intertidal barnacle Amphibalanus Amphitrite during the planktonic larval and benthic adult stages. Environmental Pollution, 267, 115560. https://doi.org/10.1016/j.envpol.2020.115560
What microscopic shells along Topsail and Surf City tell us about ancient seas, living marshes, and the future coastline
On a winter walk along the marsh edge in Topsail or Surf City, the landscape feels quiet. Cordgrass has faded to straw, tidal creeks run clear, and storm tides have pulled back layers of sediment that were hidden just months ago. Winter slows the marsh, but it also reveals it. Along exposed creek banks and tidal flats, the smallest residents of these ecosystems leave behind subtle traces — grains, spirals, and pin-sized shells that most people would mistake for sand.
These are the remains of foraminifera, key marsh indicators, and they carry a record far older than the marsh itself (Murray, 2006; Scott et al., 2001).
What Are Foraminifera?
Foraminifera, often called forams, are single-celled marine organisms — not animals, but protists — that live in oceans, estuaries, and salt marshes around the world (Murray, 2006). Despite their microscopic size, most foraminifera build protective shells, known as tests, made either from calcium carbonate or from tiny grains of sediment cemented together (Scott et al., 2001; Debenay & Guillou, 2002).
Different species occupy very specific zones within a marsh. Some live high in the intertidal, others closer to open water. Their distribution reflects precise environmental conditions such as salinity, tidal elevation, oxygen availability, and sediment type (Edwards et al., 2004; Culver & Horton, 2005). Because of this tight ecological coupling, foraminifera respond quickly when conditions change (Debenay & Guillou, 2002).
Peneropolis proteus is the one of three most dominant species of fossil foraminifera in the Onslow Bay area, occurring in about 15% of samples (Schnitker, 1971).
Why Winter Reveals the Record
In summer, marsh surfaces are busy and obscured. Dense vegetation, algae, burrowing organisms, and constant sediment mixing make it difficult to see what lies beneath. In winter, vegetation thins, biological activity slows, and storm tides rework creek edges and tidal flats. Fine sediments are redistributed, exposing layers that formed years, decades, or even centuries earlier (Scott et al., 2001; Gehrels, 1994).
Winter does not create this record — it simply makes it visible (Murray, 2006).
Size, Stability, and Ancient Seas
Some fossil foraminifera grew to the size of coins, while most living forms today are no larger than grains of sand (Murray, 2006). This contrast reflects the environments they evolved within. In ancient shallow seas, conditions were often warm, stable, and chemically consistent for long periods of time. Temperature, salinity, and carbonate availability changed slowly, allowing foraminifera to grow over many years, build thick and complex shells, and, in some cases, form partnerships with symbiotic algae — similar to the relationship between corals and the algae that live within their tissues — which provided an additional energy source through photosynthesis (Hallock, 1981; Murray, 2006). These systems favored persistence and size.
Over time, coastlines shifted and sea levels changed, giving rise to the highly dynamic estuaries and marshes we see today. In these modern environments, conditions can fluctuate over hours or seasons. Salinity rises and falls, oxygen levels vary, sediments are rearranged, and water chemistry responds quickly to storms and freshwater input (Debenay & Guillou, 2002; Culver & Horton, 2005). Under such variability, smaller foraminifera that grow rapidly and tolerate change are more likely to survive. Because foraminifera respond directly to these environmental conditions, even subtle shifts can reorganize their communities, altering shell size, composition, and diversity in ways that can persist in sediments long after the initial change has occurred (Edwards et al., 2004; Kemp et al., 2013).
Tiny Shells, Deep Time: How Marshes Remember
Foraminifera are among the most powerful tools scientists use to reconstruct ancient coastal ecosystems because the conditions they live in are permanently recorded in their shells. Individual species occupy narrow ecological ranges defined by salinity, tidal elevation, oxygen availability, temperature, and sediment type. Because of this specificity, the particular mix of foraminifera preserved in a layer of marsh sediment reflects the environmental conditions present when that layer formed.
When scientists extract sediment cores from marshes, they are not looking for isolated snapshots in time, but for transitions. As layers accumulate, changes in species composition, shifts between calcium-based shells and sediment-built shells, and variations in diversity reveal how marsh conditions evolved. These biological signals can indicate changes in flooding frequency, sediment stability, freshwater influence, and tidal reach — often aligning with known shifts in sea level or shoreline position.
What makes foraminifera especially valuable is that they record change continuously. Each generation reflects the conditions it experienced, leaving behind a layered biological archive that links past marshes to present ones — comparable to how sedimentary layers exposed in the Grand Canyon record changing environments over deep time.This continuity allows scientists to distinguish gradual environmental adjustment from more abrupt change and to assess whether modern conditions resemble states marshes have previously endured — or represent departures from historical patterns.
Quinqueloculina seminula (left) and Plancopsilina confusa (right) are the top three most dominant species of fossil foraminifera in the Onslow Bay area, each occurring in about 20% of samples (Schnitker, 1971).
What Lives in a Handful of Marsh Sand
If you scoop a small handful of sand or mud from a North Carolina marsh and let it dry, it looks ordinary—grains, bits of plant matter, flecks of shell. Where sediment cores reveal depth at the scale of decades and centuries, living marsh surfaces show that same pattern compressed into just a few centimeters. But research from the Outer Banks suggests that even this unremarkable material holds a surprisingly rich living community.
Foraminifera under biological microscope with sand.
In a detailed study of marsh sediments along the North Carolina coast, scientists examined not just which foraminifera were present, but which ones were alive at the time of sampling. What they found was not a thin layer of life resting at the surface, but a vertically structured community extending down into the sediment itself (Culver, 2005).
Some foraminifera lived right at the surface, where tides regularly wash over the marsh. Others occupied sediments a centimeter or more below, in darker, less oxygenated layers. In total, more than twenty species were documented living within marsh sediments, their distributions shaped by subtle differences in tidal flooding, salinity, and marsh elevation (Culver, 2005).
Not all species were equally widespread. A few, including Jadammina macrescens and Tiphotrocha comprimata, appeared across multiple sites and depths, suggesting a tolerance for changing marsh conditions. Many others were more selective, occurring only in certain zones or at particular depths. This means that even small changes in where you stand—closer to a tidal creek or higher on the marsh platform—can correspond to a different microscopic community beneath your feet (Culver, 2005).
Upper image: Jadammina macrescens under microscope.| Image credit: Parker, G. G., Phleger, et al. 1953. Cushman Found.Foram.Research Spec.Pub. (n.2): 15, pl.3,f.8. Lower image:Tiphotrocha comprimata under microscope | Image credit: Hesemann, M., The Foraminifera.eu Database (2026). Accessed at http://www.foraminifera.eu. https://doi.org/10.13140/RG.2.2.22727.11680/1.
As these organisms die, their shells remain. Layer by layer, those shells become part of the sediment, preserving a record of where tides reached, how often flooding occurred, and how stable the marsh surface was at that moment in time (Scott et al., 2001). What begins as a living community quietly becomes part of the marsh’s long-term record.
Although the Outer Banks are not identical to the marshes behind Topsail and Surf City, the pattern holds across North Carolina’s coast: foraminifera respond to local conditions at very small scales. Their presence, abundance, and depth within the sediment shift from place to place, reflecting the marsh’s relationship with water, salt, and time (Edwards et al., 2004; Culver & Horton, 2005).
Cibicidoides bradyi (horizontal scale bar = 200μm, vertical scale bar = 400μm) occur in less than 20 m at about 1% of samples in the Onslow County area (Schnitker, 1971).
For someone walking the marsh in winter, this means that the sand exposed along a creek bank carries more than the imprint of the last storm. It carries traces of countless tides before it—each one leaving behind shells small enough to escape notice, yet durable enough to remember.
What Changes in Foraminifera Mean for the Ecosystem
An example of how shifts in reef communities reflect shifts in foraminiferal communities below (Prazeres, Martínez-Colón & Hallock, 2020).
Foraminifera do not exist in isolation. They are part of the marsh food web, contributing to the transfer of energy and nutrients from microscopic primary producers to larger organisms (Murray, 2006). Many small invertebrates consume foraminifera directly, while others rely on the microbial communities and organic matter associated with their shells (Debenay & Guillou, 2002). In turn, these invertebrates support fish, crabs, and birds that depend on marsh productivity (Scott et al., 2001).
When foraminiferal communities shift, the effects can ripple outward. A decline in diversity or a move toward stress-tolerant species often reflects changes in sediment stability, oxygen availability, or salinity — conditions that also influence marsh plants, benthic invertebrates, and juvenile fish habitat (Culver & Horton, 2005; Edwards et al., 2004). In this way, changes in foraminifera can foreshadow broader ecological adjustments, even when the marsh surface still appears healthy (Debenay & Guillou, 2002).
Because foraminifera respond quickly to environmental change, they often register these shifts before larger organisms do. Their shells capture early signals of altered flooding patterns, reduced sediment input, or changing water chemistry (Gehrels, 1994; Kemp et al., 2013). What follows may be changes in plant community structure, altered nutrient cycling, or shifts in the species that use marshes as nursery grounds. Foraminifera do not cause these changes, but they reveal when the system’s internal balance begins to shift (Scott et al., 2001).
Reading Change in Living Marshes
Salt marshes are dynamic systems by nature. They grow, erode, migrate, and rebuild as sediment moves and sea level changes (Kemp et al., 2013). The challenge for scientists is distinguishing normal variability from directional change — shifts that push marshes beyond the conditions they have historically been able to tolerate. Foraminifera are especially useful in making that distinction because they respond quickly and directly to their surroundings (Debenay & Guillou, 2002).
When marsh conditions move outside typical ranges — whether through altered hydrology, changes in sediment supply, or shifts in salinity — foraminiferal communities reorganize. Species diversity may decline, stress-tolerant forms can become dominant, and assemblages tied to specific tidal elevations may disappear (Culver & Horton, 2005). These changes often occur before larger, more visible signs of stress appear, such as widespread plant die-off or shoreline erosion (Edwards et al., 2004). In this sense, foraminifera act as early responders, recording change while the marsh still appears intact at the surface (Scott et al., 2001).
Along the marshes behind Topsail and Surf City, this sensitivity gives foraminifera particular importance. They help establish local baselines for what healthy marsh conditions look like, provide context for interpreting present-day shifts, and preserve a record of the conditions that supported marsh stability in the past (Culver & Horton, 2005; Kemp et al., 2013). By linking modern observations to sedimentary records, foraminifera allow scientists to ask not only what is changing, but how quickly change is occurring and whether it remains within the range marshes have previously endured. Understanding marsh resilience in this way is not abstract or theoretical — it is grounded in the specific history and behavior of this coastline.
Salt marsh in Surf City, NC. | Photo credit: Mitchell (2026)
Closing
Standing at the marsh edge in winter, it is easy to miss the smallest details. Yet beneath the quiet surface, microscopic shells record centuries of change — how water moved, how shorelines shifted, and how marshes adapted (Murray, 2006). Foraminifera remind us that long before satellites or tide gauges, coastlines were already keeping their own records. All we have to do is learn how to read them.
References
Culver, S. J. (2005). Infaunal marsh foraminifera from the Outer Banks, North Carolina, U.S.A. The Journal of Foraminiferal Research, 35(2), 148-170. https://doi.org/10.2113/35.2.148
Debenay, J., & Guillou, J. (2002). Ecological transitions indicated by foraminiferal assemblages in paralic environments. Estuaries, 25(6), 1107-1120. https://doi.org/10.1007/bf02692208
Edwards, R., Wright, A., & Van de Plassche, O. (2004). Surface distributions of salt-marsh foraminifera from Connecticut, USA: Modern analogues for high-resolution sea level studies. Marine Micropaleontology, 51(1-2), 1-21. https://doi.org/10.1016/j.marmicro.2003.08.002
Gehrels, W. R., & Kemp, A. C. (2021). Salt marsh sediments as recorders of Holocene relative sea-level change. Salt Marshes, 225-256. https://doi.org/10.1017/9781316888933.011
Kemp, A. C., Horton, B. P., Vane, C. H., Berhhardt, C. E., Corbett, D. R., Engelhart, S. E., Anisfeld, S. C., Parnell, A. C., & Cahill, N. (2013). Sea-level change during the last 2500 years in New Jersey, USA. Quaternary Science Reviews, 81(2013), 90-104. https://www.whoi.edu/cms/files/Kemp2013QSR_170144.pdf
Murray, J. W. (2006). Ecology and applications of benthic foraminifera. Cambridge University Press.
Schnitker, D. (1971). Distribution of Foraminifera on the North Carolina Continental Shelf. Tulane Studies in Geology and Paleontology, 8(4), 169-215. https://journals.tulane.edu/tsgp/article/view/560
Scott, D. B., Medioli, F. S., & Schafer, C. T. (2001). Monitoring in coastal environments using foraminifera and Thecamoebian indicators. Cambridge University Press.
Winter birds and hidden skates in a changing coastal system
Late December along the coast does not announce itself loudly. The holidays have passed, the shoreline empties, and the light—almost imperceptibly—begins to return. The winter solstice marks the shortest day of the year, but its ecological counterpart is quieter. The water does not reset. It settles.
This is the moment when the coastal ecosystem stops negotiating with the season and begins to accept it. That acceptance is visible, if you know where to look—above the waterline in the form of a small diving duck, and below the surface in the stillness of a benthic predator that does not announce its presence at all.
In our region, ecologists recognize certain animals as threshold species: species whose presence, or subtle change in behavior, signals that the system has crossed a seasonal threshold in energy, behavior, and stability — moving from late year into what comes next.
Above the Water: When Winter Is No Longer a Question
Male (left) and female (right) Bufflehead ducks enjoying a winter swim | Photo credit: Judy Gallagher, iNaturalist
By late December, one species begins to appear with quiet regularity across protected sounds and estuaries: the Bufflehead(Bucephala albeola).
Buffleheads are not early winter arrivals. They do not surge in during the first cold fronts of autumn, nor do they linger indecisively during seasonal transition. Instead, their presence reflects commitment. By the time buffleheads settle into coastal waters, water temperatures have stabilized at winter lows, turbulence has eased in protected areas, and benthic prey communities—particularly small crustaceans and mollusks—have shifted into predictable winter distributions (Eadie et al., 2000; Goudie et al., 1994).
Ecologically, buffleheads are specialists. They forage by diving, relying on clear water and reliable prey patches. Their winter distribution is shaped not by calendar dates but by energy economics: cold water increases metabolic demands, and winter habitats must reliably repay that cost (Eadie & Kehoe, 2022). Where buffleheads remain, the system has crossed a threshold from fluctuation to stability.
In this way, they function less as migrants and more as indicators. Their presence signals that the coastal year has finished rearranging itself. Winter has arrived—not dramatically, but decisively.
Below the Water: When Stillness Makes Life Visible
Clearnose skate in winter waters | Photo credit: NOAA Fisheries
Below the surface, the signal is subtler.
Skates do not arrive in winter with the clarity of birds overhead. Species such as the Clearnose skate(Rostroraja eglanteria) are present along the southeastern U.S. coast throughout much of the year. What changes in late December is not their location, but their visibility.
As water temperatures drop, skates reduce activity, conserving energy through decreased movement and prolonged periods of resting on the seafloor (Di Santo & Bennett, 2011). This metabolic slowdown coincides with seasonal increases in water clarity driven by reduced biological productivity, lower sediment resuspension, and diminished boat traffic (Cloern et al., 2014). The result is a paradox: winter reveals what summer conceals.
In these conditions, skates become easier to observe—not because they have increased in number, but because the system itself has slowed enough to make persistence visible. Their flattened bodies blend seamlessly into sandy or muddy substrates, a strategy optimized for ambush predation and energy conservation rather than movement (Carrier et al., 2012).
If buffleheads announce that winter has settled, skates confirm it. They represent endurance over motion, patience over migration.
The Ecological Hinge Between Years
Neither of these species marks a beginning. Neither signals renewal or arrival in the way spring migrants do. Instead, they occupy the hinge between years—the moment when the ecosystem accepts the constraints of winter and reorganizes around them.
Late December is not biologically empty. It is a period of recalibration. Energy budgets tighten. Movements become deliberate. Survival depends less on abundance than on efficiency.
Above the water, buffleheads gather where the math works. Below it, skates persist by minimizing expenditure altogether. One is easily seen, the other almost never. Together, they reveal the same truth: the system has crossed a line.
After the Turn
January will bring its own changes. Cold will deepen, or ease. Migratory patterns will sharpen. New signals will emerge. But the moment just after the solstice—just after the holidays—is different. It is when the coast pauses, holds, and commits.
The year does not turn loudly here. It settles, and then it holds.
References
Carrier, J. C., Musick, J. A., & Heithaus, M. R. (2012). Biology of sharks and their relatives (2nd ed.). CRC Press. https://doi.org/10.1201/b11867
Cloern, J. E., Foster, S. Q., & Kleckner, A. E. (2014). Phytoplankton primary production in the world’s estuarine–coastal ecosystems. Biogeosciences, 11(9), 2477–2501. https://doi.org/10.5194/bg-11-2477-2014
Di Santo, V., & Bennett, W. A. (2011). Is post-feeding thermotaxis advantageous in elasmobranch fishes? Journal of Fish Biology, 78(7), 1950–1965. https://doi.org/10.1111/j.1095-8649.2011.02976.x
Eadie, J. M., & Kehoe, F. P. (2022). Energetics and foraging ecology of diving ducks. In P. G. Rodewald (Ed.), The birds of North America. Cornell Lab of Ornithology. https://doi.org/10.2173/bna
Eadie, J. M., Savard, J. P. L., & Mallory, M. L. (2000). Barrow’s Goldeneye (Bucephala islandica) and Bufflehead (Bucephala albeola). In A. Poole & F. Gill (Eds.), The birds of North America. Cornell Lab of Ornithology. https://doi.org/10.2173/bna.548
Goudie, R. I., Brault, S., Conant, B., Kondratyev, A. V., Petersen, M. R., & Vermeer, K. (1994). The status of sea ducks in the North Pacific Rim: Toward their conservation. Transactions of the North American Wildlife and Natural Resources Conference, 59, 27–49. https://pubs.usgs.gov/publication/70187692
