The expedition, conducted in the summer of 2025 aboard a research cruise funded by the Schmidt Ocean Institute, marked the first time scientists had captured images of the seafloor within the Mar del Plata Submarine Canyon. Using a remotely operated submersible, the team carried out seventeen dives into the canyon system, revealing a landscape teeming with life as well as litter. Among the discoveries were approximately forty species that may be new to science, a reminder of how little is known about deep-sea biodiversity even as human refuse arrives there. The same dives that documented unfamiliar organisms also recorded twenty-nine identifiably manmade objects across ten of the dives, a striking proportion for a habitat so far from any coastline.

The technical details of the debris survey are sobering. The vast majority of the objects were plastic, accompanied by a smaller number of rubber items. The catalog ranged from fishing gear to plastic bags, food wrappers, snack wrappers, a tissue paper wrapper, a nylon cord with a hook, a white plastic cup, and a rubber boot. Depth records for individual items read like a descent into the abyss: a plastic wrapper at 2,109 meters, a food wrapper at 1,920 meters, a snack wrapper at 3,231 meters, a sediment-filled plastic bag at 3,739 meters, a highly degraded plastic fragment at 3,709 meters, and a plastic cup and bag at 3,243 meters. The boot, resting at 2,598 meters, offered perhaps the most vivid illustration of how ordinary consumer items can end up kilometers beneath the waves.

Equally significant was the spatial pattern the researchers observed. Litter was more abundant inside the canyon than in the surrounding seafloor, suggesting that the canyon’s topography and the currents flowing through it act as a funnel, concentrating drifting debris into the fissure. Submarine canyons are known to channel sediments and organic material from the continental shelf into the deep ocean, and the new evidence indicates that buoyant and neutrally buoyant trash follows the same routes. Items were found in a variety of states: some were partially buried in sediment, others were trapped among rocks, and a few were still drifting, indicating that debris continues to arrive rather than representing only a legacy of past pollution.

The study also recorded how deep-sea animals interact with the waste, and the picture is more complicated than simple avoidance. Mobile creatures such as crustaceans showed transient interactions with the debris, passing over or briefly investigating the foreign objects. More sedentary organisms, including starfish and corals, were observed attached to some items, with plastic packaging and fishing ropes often partially subsumed by the animals growing on them. To a filter-feeding coral or an anchored starfish, a length of sunken rope may present a surface resembling the hard substrate that is otherwise scarce on soft sediment plains. The researchers cautioned, however, that these observations should not be mistaken for evidence that the debris provides suitable habitat. The long-term consequences of colonization on plastic in the deep sea remain unknown.

The discovery in the Mar del Plata Submarine Canyon is not an isolated case. Just a few months before this expedition, a plastic bag was found in the Mariana Trench, the deepest fissure on the planet, demonstrating that no ocean depth is beyond the reach of human waste. The sinking of organic material from the surface is essential to sustaining life in the darkness below, where sunlight never penetrates and food must arrive from above. The new study adds to emerging evidence that this vertical rain of nutrients is not the only matter being pulled to the ocean floor. Debris generated on land and at sea follows the same gravitational and oceanographic pathways, settling into the very environments that depend on the steady delivery of material from the surface ocean.

For the scientists involved, the expedition carried a profound emotional weight alongside its technical achievements. The authors reflected on the experience of exploration in the deep: “Unveiling a species previously unknown to science in the endless darkness of the deep sea may be one of the most extraordinary experiences a marine biologist can have.” That sense of wonder makes the presence of trash all the more jarring. The same dives that revealed organisms never before seen by human eyes also revealed the unmistakable fingerprints of consumer culture, from snack wrappers to plastic cups, resting among creatures that evolved over hundreds of millions of years without any contact with synthetic materials.

The research was a genuinely international effort, with authors from Argentina, Ecuador and the United States, and it was supported by a broad coalition of funders including the Schmidt Ocean Institute, the Nippon Foundation-Nekton Ocean Census Programme, the CORDAP Coral Accelerator Program, the AZARA Foundation, Argentina’s Agencia I+D+I and CONICET, and Fundación ProyectoSub. The expedition designation FKt250712 will likely be remembered as a milestone in the documentation of the southwestern Atlantic’s deep-sea environments. All images of the litter were captured by the ROV SuBastian and released under a Creative Commons license, allowing the public to see for themselves what lies nearly four kilometers beneath the surface of the Atlantic.

What emerges from the study is a revised mental map of human influence on the ocean. On average, the oceans are only a few miles deep, and as the researchers note, the sea floor is not as distant from human activity as it may seem. Every wrapper, bag and fragment of fishing gear that escapes into the sea has a destination, and increasingly that destination is the deep. The Mar del Plata Submarine Canyon, with its newly documented species and its accumulated debris, offers a preview of what awaits other unexplored canyon systems around the world. The findings underscore that protecting deep-sea ecosystems requires addressing plastic pollution at its sources, because once trash reaches these environments, monitoring it is difficult and removing it may be impossible with current technology.

The open access publication of the study in PLOS One ensures that the evidence is freely available to researchers, policymakers and the public alike. As deep-sea exploration technology becomes more accessible and remotely operated vehicles descend into more canyons, trenches and abyssal plains, scientists expect that similar discoveries will follow. The deep ocean, it turns out, is not a separate world insulated from the one above. It is connected by currents, by sinking particles, and now demonstrably by our garbage. The question raised by the Mar del Plata survey is not whether human debris can reach the deepest corners of the sea, but how much is already there, unseen, in the darkness waiting to be explored.

Subject of Research: Marine litter accumulation in the deep-sea Mar del Plata Submarine Canyon

Article Title: The depths of the ocean aren’t immune to human debris

Article References: The depths of the ocean aren’t immune to human debris. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: deep sea, marine litter, plastic pollution, submarine canyon, ROV survey, PLOS One, southwestern Atlantic, biodiversity, Mariana Trench, ocean currents, deep-sea ecosystems, Argentina

The research, published in the journal Natural Hazards, was carried out by Fernando Oreiro of Argentina’s Servicio de Hidrografía Naval and the University of Buenos Aires, Iael Perez of the Finnish Environment Institute, and Walter Dragani of CONICET and several Argentine research institutions. The team took advantage of a rare observational asset: simultaneous sea-level records collected between January and April 2018 at paired offshore and inner-harbor stations associated with three very different ports along the southwestern Atlantic coast. Those ports were Montevideo, the Uruguayan capital sitting on the Río de la Plata; Mar del Plata, a busy fishing and tourist harbor on the open Argentine coast; and Quequén, a deepwater grain port farther south, whose estuary entrance is famous among coastal scientists for its violent short-period oscillations.

The raw tide-gauge data, like all sea-level records, contains a mixture of signals: slow tides, storm surges that build over hours or days, and the rapid oscillations that interest meteotsunami researchers. To isolate the latter, the authors applied a high-pass filter to each record, stripping away the long-period background and leaving the oscillations with periods shorter than roughly a few hours. What emerged was a striking pattern in time. Episodes of energetic long-wave activity did not appear at one port in isolation; they arrived in sequence, first at Quequén, then at Mar del Plata, and finally at Montevideo. This northward progression matched the northeastward track of cold fronts sweeping across the region, pointing to atmospheric gravity waves trailing those fronts as the likely trigger for the ocean oscillations.

To go beyond visual inspection of the filtered records, the team turned to spectral analysis, a mathematical technique that decomposes a wobbly time series into the amplitudes of the individual frequencies that make it up. Comparing the spectrum measured offshore with the spectrum measured inside each harbor reveals how the local basin transforms incoming wave energy. If a harbor acts as a resonator, it amplifies particular frequencies, just as a wine glass rings at a specific pitch when struck. The classic theory of harbor oscillation, developed in the early 1960s by researchers such as John Miles and Walter Munk, predicts that each basin has a set of natural, or eigen, periods determined by its size, depth, and geometry. The new study put that theory to a natural test across three basins of very different shape.

The results were anything but uniform. Montevideo Bay displayed the strongest amplification of the three sites, with a persistent enhancement of sea-level energy concentrated at relatively low frequencies. In other words, when long waves associated with frontal passages swept into the Río de la Plata, the broad bay rang like a resonating chamber, steadily boosting energy at the low end of the spectrum. Mar del Plata Harbor behaved differently: its amplification was weaker and spread across a broader, more irregular band of frequencies, suggesting a more complicated resonant structure with multiple modes of varying strength rather than a single dominant one. Quequén Harbor, despite its reputation for dramatic oscillations, showed comparatively weak spectral enhancement inside the port relative to the offshore signal, maintaining a much closer correspondence with the long-wave field arriving from the shelf.

Because spectra averaged over the whole four-month record can hide how the relationship between offshore and harbor signals evolves through individual events, the researchers also applied wavelet coherence analysis, a technique that measures how tightly two time series are linked at each frequency and at each moment in time. The method, popularized for geophysical data in a widely cited 2004 paper by Grinsted and colleagues, allowed the team to see when harbor and offshore oscillations were locked in step and when they drifted apart. At Quequén, the coherence between the offshore long-wave field and the harbor response was persistent and strong, reinforcing the picture of a port that largely transmits and modestly reshapes the incoming wave energy. At Mar del Plata, coherent coupling was present but less continuous. Montevideo showed the weakest and most intermittent coherence, implying that the bay’s response is governed more by its own internal resonance than by a direct, moment-to-moment coupling with the offshore signal.

These findings carry a subtle but important message for how coastal scientists think about harbor hazards. It is tempting to assume that a port’s vulnerability to meteotsunamis can be predicted from its theoretical oscillation periods alone: compute the natural modes of the basin, compare them with the frequencies contained in the incoming atmospheric disturbance, and flag any overlap. The comparative data from the southwestern Atlantic complicates that picture. The authors conclude that harbor amplification depends not only on basin geometry and theoretical resonant periods, but also on the trajectory and incidence angle of the incoming disturbance. A wave train arriving along one bearing may couple efficiently into a harbor’s modes, while the same basin may barely respond to an energetically equivalent disturbance approaching from a different direction. Numerical work by other groups, including studies of harbor oscillation induced by pressure disturbances moving in different directions along the Yellow Sea coast, has pointed to the same conclusion, but few observational studies have documented it across multiple real ports at once.

The regional context amplifies the significance of the work. The Buenos Aires continental shelf is exceptionally wide and shallow, and previous research, including a 2022 case study by Dragani and colleagues and a 2024 review of global meteotsunami hazards published in Reviews of Geophysics, has established that atmospheric disturbances crossing this shelf frequently generate long ocean waves through a resonant mechanism known as Proudman resonance, in which a fast-moving pressure disturbance drags a growing ocean wave beneath it. When these waves encounter the coast, they can excite seiches, the standing oscillations of bays and harbors, with catastrophic local consequences. The 2022 event was particularly remarkable, occurring simultaneously along the Argentine and Uruguayan coasts and coinciding with the arrival of the Tonga volcanic tsunami, an overlap documented in a 2025 study by the same research group. Understanding which harbors transform such wave energy into dangerous currents is therefore a matter of practical port safety as well as fundamental science.

For port authorities, the comparative framework offers a concrete lesson: two harbors facing the same open ocean can be exposed to very different risks from the same storm system. Montevideo’s persistent low-frequency amplification means that slow, large-volume oscillations are its signature hazard, with implications for mooring design and berthing operations during frontal passages. Mar del Plata’s irregular, broad-band response suggests that many different atmospheric disturbance types can find some resonant frequency to excite there. Quequén’s relatively faithful reproduction of the offshore signal implies that its risk profile is tied directly to the strength of the shelf wave field itself. The work, which was supported by Argentina’s National Scientific and Technical Research Council, also demonstrates the value of simply measuring the same events at paired offshore and harbor stations, an approach the authors suggest can sharpen meteotsunami hazard assessments well beyond the classical eigenperiod calculation. As climate-driven changes in atmospheric circulation continue to alter the frequency and character of frontal systems worldwide, knowing not just where meteotsunamis form but how each harbor listens to them may prove essential for the ports of the southwestern Atlantic and beyond.

Subject of Research: Frequency-dependent harbor response to meteotsunamis along the Argentine and Uruguayan coasts

Article Title: Comparative frequency-dependent harbor response to meteotsunamis along the Argentine and Uruguayan coasts

Article References: Oreiro, F., Perez, I., & Dragani, W. (2026). Comparative frequency-dependent harbor response to meteotsunamis along the Argentine and Uruguayan coasts. Natural Hazards, 122(20), Article 648. https://doi.org/10.1007/s11069-026-08408-y

Image Credits: AI Generated

DOI: 10.1007/s11069-026-08408-y

Keywords: meteotsunami, harbor resonance, sea level oscillations, atmospheric gravity waves, spectral analysis, wavelet coherence, Argentina, Uruguay, Natural Hazards, coastal hazards, seiches, southwestern Atlantic