The new study, published open access in Discover Oceans, was led by Jaime-Leigh Lue Chin of the University of the West Indies with colleagues from the Natural History Museum in London, the University of British Columbia, the Institute of Marine Affairs, and the University of California, Santa Barbara. The team scoured biodiversity databases such as the Global Biodiversity Information Facility and the Ocean Biogeographic Information System, combed through the collections of major museums including the Smithsonian National Museum of Natural History and Harvard’s Museum of Comparative Zoology, searched more than 1,300 literature results, and physically examined reference collections held in Trinidad and Tobago itself. Every record had to meet strict criteria: confirmed coordinates inside the Exclusive Economic Zone, a depth of at least 200 meters, a date, and a named expedition or institution.

What emerged was a dataset of 1,342 unique biological records spanning ten animal phyla, gathered over 57 years between 1957 and 2014. Of the documented morphospecies, 315 are benthic, living on or in the seafloor, while 136 are pelagic, drifting or swimming in the water column. Chordates dominated the records with 254 morphospecies, followed by arthropods with 96. Most of what has been found so far is megafauna, the large animals visible to cameras and trawls, while the smaller macrofauna, meiofauna, and microbes that drive deep-sea ecosystem functioning remain essentially unstudied. Among the most frequently recorded species were the methane-seep mussel Gigantidas childressi, logged 101 times, and tubeworms of the genus Lamellibrachia, recorded 68 times, both foundation species that create habitat for entire communities.

The geography of discovery is strikingly uneven. Sampling has clustered east of Tobago and along the 200-meter contour of the continental slope in the southeastern waters, with the 400 to 600 meter depth band surveyed most intensively. The two densest hotspots of biological records sit alarmingly close to leased oil and gas blocks: the El Pilar methane seeps and mud volcanoes in the northeast, and the Orenoque-A site in the southeast. Below roughly 2,049 meters, an area covering about 20 percent of the entire Exclusive Economic Zone, no biological research has ever been conducted. The deep pelagic zone, which constitutes the majority of the nation’s living space, has received almost no attention, with no pelagic records at all from depths beyond 2,000 meters.

Statistical analysis makes clear how incomplete the picture remains. Using the Chao2 incidence-based estimator, the team projected a total benthic species richness of around 828 and a pelagic richness of around 772, compared with the 313 benthic and 137 pelagic species actually observed. Family-level richness was estimated at 346 against 218 recorded. The rarefaction and extrapolation curves remain far from their asymptotes, meaning that every additional expedition keeps adding new species. That pattern strongly suggests a large reservoir of undiscovered biodiversity. The most recent expedition to the area, which sampled only about 0.002 percent of the deep sea, still turned up 83 megafaunal morphospecies, at least five of which appeared to be new to science.

The geological setting helps explain why this deep sea is so unusual. Trinidad and Tobago sits on the southern edge of the Barbados Accretionary Prism, one of the largest sediment wedges on Earth, formed where the Atlantic Plate slides beneath the Caribbean Plate. The same tectonic processes that scrape up sediment also generate large oil and natural gas reserves, mud volcanoes, and methane seeps, where chemical-rich fluids carrying sulphide and methane fuel chemosynthesis-based ecosystems that thrive without sunlight. Some of the tubeworms found in these waters, such as Escarpia laminata, live for more than 300 years, meaning damage from industrial activity could take centuries to heal. Deep-sea communities generally recover far more slowly than shallow-water ones, making them especially vulnerable to physical disturbance, pollution, and sediment resuspension from drilling.

The study also exposes a stark legacy of what researchers call parachute science. Not a single one of the eleven vessels or expeditions that have sampled the nation’s deep sea originated from Trinidad and Tobago or anywhere else in the Caribbean. Five were linked to United States institutions, one to France, one to Norway, one to Canada, and two were likely commercial vessels tied to the oil and gas industry. Just three foreign-led expeditions, the R/V Dr. Fridtjof Nansen in 1988, the R/V Atlantis II in 1973, and the E/V Nautilus in 2014, account for nearly three quarters of all records. Perhaps most tellingly, an estimated less than 9 percent of the physical samples collected in the country’s waters have remained in-country. Over 89 percent are housed abroad, with 72.7 percent in the United States and 15.3 percent in the United Kingdom, including large holdings at Harvard, the Smithsonian, the University of Southampton, and the Florida Museum of Natural History.

The methodological record is equally lopsided. Trawling was the workhorse of most expeditions, with eight of the eleven using net-based gear, which explains the apparent dominance of fishes and crustaceans and the near-total absence of delicate soft-bodied animals such as cnidarians, bryozoans, ctenophores, and nemerteans. Only two expeditions deployed remotely operated or human-occupied vehicles, yet those dives recorded the greatest taxonomic diversity, capturing every phylum identified and revealing habitat-specific communities like chemosynthetic mussels and tubeworms that trawls would have shredded or missed entirely. ROV surveys averaged depths of about 1,223 meters compared with just 484 meters for benthic trawling, showing how technology determines what science can see. Image-based surveys, meanwhile, often cannot resolve species without physical specimens for morphological or molecular analysis, leaving many animals unidentified.

The authors argue that closing these gaps demands a multipronged strategy tailored to a Small Island Developing State that cannot afford its own research vessel, given that deep-sea expeditions cost anywhere from tens of thousands to millions of dollars. They propose shared regional assets coordinated through the Caribbean Community, equitable international partnerships in which local scientists lead study design and interpretation, and targeted investment in education and technology transfer. They also point to an underused resource close to home: the offshore oil and gas industry, the only stakeholder currently operating at scale in the deep sea, holds high-resolution bathymetric maps, sampling platforms, and environmental data that could transform baseline knowledge if made accessible. Models such as the SERPENT Project have already shown that scientific partnerships with offshore operators can yield valuable biodiversity data.

Ultimately, the researchers frame this baseline as a foundation for stewardship rather than an endpoint. The findings support a precautionary approach, pointing to vulnerable marine ecosystems such as the El Pilar methane seeps, which remain entirely unprotected despite supporting dense aggregations of ecosystem engineers and playing roles in oceanic food webs and climate regulation. Evidence of regional connectivity, with faunal links to Grenada, the Mid-Cayman Spreading Centre, the Gulf of Mexico, and even Brazil, means that what happens in Trinidad and Tobago’s deep sea resonates across the wider Atlantic. Notable records, including the first Caribbean sighting of the tanaid Carpoapseudes heardi, the recently described tubeworm Lamellibrachia judigobini, and the lithodid crab Paralomis arethusa, hint at how much more awaits discovery. With the government actively leasing deepwater blocks and climate pressures mounting, the authors conclude that the time to invest in deep-sea knowledge, local capacity, and evidence-based ocean governance is now, before the country’s largest and least understood ecosystem is altered beyond recognition.

Subject of Research: Deep-sea biodiversity baseline assessment in Trinidad and Tobago's Exclusive Economic Zone

Article Title: A baseline assessment of deep-sea biodiversity, and guide for future actions to inform stewardship, in Trinidad and Tobago

Article References: Lue Chin, J.-L., Rabone, M., Palacios-Abrantes, J., Gobin, J., Jute, A., Kanhai, L. D. K., & Amon, D. J. (2026). A baseline assessment of deep-sea biodiversity, and guide for future actions to inform stewardship, in Trinidad and Tobago. Discover Oceans, 3(1), Article 18. https://doi.org/10.1007/s44289-026-00119-3

Image Credits: AI Generated

DOI: 10.1007/s44289-026-00119-3

Keywords: deep-sea biodiversity, Trinidad and Tobago, methane seeps, marine conservation, Exclusive Economic Zone, parachute science, oil and gas, Small Island Developing States, species richness estimation, Barbados Accretionary Prism, ocean stewardship, benthic ecosystems

The challenge the researchers set out to solve is one that has frustrated coastal scientists for decades. Satellites can track ocean productivity in the open sea by detecting the green pigment of phytoplankton, and these observations have transformed our understanding of global carbon cycling and marine food webs. But in shallow, murky estuaries, the algorithms fail. Suspended sediments and colored dissolved organic matter absorb and scatter light in ways that confuse the satellite signal, and in very shallow water the seafloor itself reflects and absorbs light, further muddying the picture. Yet it is precisely these shallow systems where the seafloor matters most: as water depth decreases, the biomass of benthic producers such as microalgae, turfing algae, and seagrass per unit of seabed increases, while the phytoplankton biomass in the water column above that seabed shrinks. In estuaries averaging two meters deep or less, seabed production can account for the majority of the ecosystem’s total primary productivity.

To see past the murk, the team built their model from the ground up, using empirical measurements rather than satellite data. The approach had three pillars. First, they constructed a harbor-specific seabed light model, driven by incident sunlight recorded at a weather station near Whakatane, bathymetry assembled from vessel surveys and LIDAR, and turbidity profiles collected at more than forty locations throughout the harbor. Boosted regression tree models, trained on 1,243 paired measurements of light penetration, depth, and turbidity, predicted the percentage of surface light reaching every ten-by-ten-meter grid cell of the harbor at two-hourly intervals across an entire year, with a mean deviance explained of 0.94. Second, they mapped the distribution of the three dominant seabed habitats: seagrass, sand, and mud. Third, they linked light to life through habitat-specific photosynthesis-irradiance curves derived from aquatic eddy covariance deployments, an instrument technique that measures oxygen exchange between the seafloor and overlying water continuously, at high frequency, over multiple day-night cycles.

Those photosynthesis-irradiance curves revealed striking differences among habitats. Seagrass reached a maximum photosynthetic rate of 183 millimoles of oxygen per square meter per day, five and a half times higher than mud at 33.1 and more than double that of sand at 88.1. But seagrass also consumed oxygen fastest at night, at 72.3 millimoles per square meter per day, compared with 47.6 for sand and 28.6 for mud. Each habitat switched from net oxygen consumption to net production at a different light threshold, known as the compensating irradiance point: mud required the least light, at 23.8 micromoles of photons per square meter per second, sand needed 34.6, and seagrass needed 69.3. These curves, combined with the habitat map and the light model, allowed the researchers to compute net oxygen flux for every grid cell, every two hours, for a full year from June 2020 to May 2021.

The resulting maps are visually arresting. Patches of intertidal seagrass blaze bright green as hotspots of production, while the deeper subtidal channels appear in dark hues even where the sediment type is identical to shallower areas nearby, because light attenuates with depth. When the daily values were averaged across the whole harbor, a clear seasonal rhythm emerged. Winter, from June to August, was the low point, with productivity of 44.7 plus or minus 8.9 millimoles per square meter per day, significantly lower than the other three seasons. Spring averaged 55.9, autumn 53.1, and summer 51.5, none significantly different from one another. The single lowest day fell on June 25, 2020, at 16.7 millimoles per square meter per day, and the highest on September 9, 2020, at 65.1. July was the weakest month overall, averaging 38.6, significantly below every other month.

Perhaps the most remarkable finding is that Ōhiwa Harbour remained net autotrophic—producing more oxygen than it consumed—on every single day of the year, even in the depths of winter when turbidity was highest and sunlight weakest. Monthly average productivity never dropped below 38 millimoles per square meter per day. The researchers attribute this resilience to the harbor’s extreme shallowness: 79 percent of it is intertidal, and the high productivity of shallow seafloor relative to deep water kept the system in the black. Seagrass, despite covering only three percent of the seascape, punched far above its weight, contributing two to five times the productivity of other habitats under high light. The team notes that even though their seagrass curve was built from data collected outside Ōhiwa and in a single season, the harbor-wide patterns are relatively robust to inaccuracies in that curve because seagrass occupies such a small fraction of the domain.

The implications reach well beyond one New Zealand estuary. Estuaries are widely described as among the most productive habitats on Earth, yet whole-estuary productivity dynamics have rarely been mapped, leaving a gap in our ability to protect areas of high ecosystem functioning—a strategic goal of the Kunming-Montreal Global Biodiversity Framework. The stakes are rising. Climate change is expected to increase sediment loads to estuaries through more frequent and intense storms, while sea level rise deepens shallow systems, and together these forces are “darkening” estuarine seabeds, cutting the light that fuels benthic production. Meanwhile, the historical reclamation of shallow intertidal habitats near coastal cities has likely reduced the oxygen-producing capacity of those systems, potentially contributing to the hypoxic zones that have accumulated exponentially worldwide since the 1950s, with consequences ranging from altered biogeochemistry to fish kills and shellfish die-offs.

The study also carries a cultural dimension. The researchers worked alongside Ngāti Awa, the Indigenous Māori guardians of Ōhiwa Harbour, whose restoration efforts recently led to the return of dense beds of green-lipped mussels near the harbor entrance. Māori conceptualize waterways as living beings whose vitality, or mauri, depends on the health of all their parts, much like the organs of a body. The pulsed daily, tidal, and seasonal rhythms of productivity the model revealed resonate directly with this worldview: the seafloor as a breathing lung whose maintenance sustains the whole. The mussel beds themselves illustrate a subtlety of valuation—a dense mussel bed is likely a net oxygen sink because of its enormous animal biomass, yet it delivers food, water purification, and food web support, showing that low seabed production does not mean low value.

The authors are candid about limitations. The model is heuristic rather than strictly predictive: seagrass distribution was a single snapshot in time, sand and mud were treated as homogeneous, intertidal production was assumed to match submerged production at maximum irradiance, and only a quarter of the eddy covariance deployments occurred within Ōhiwa itself, in winter only. With updated habitat layers, the framework could become far more accurate. Even so, the team has provided something coastal managers have lacked: a transferable tool, with code publicly available on Figshare, that can predict estuary primary productivity under different scenarios of climate change, sea level rise, sediment loading, and habitat loss. Local actions—fencing stock from riparian edges, afforesting catchments, ending logging on steep slopes—cannot stop the sea from rising, but they can keep the estuary’s lungs working, sustaining the shellfish, fish, biodiversity, and nutrient removal services that depend on them.

Subject of Research: Mapping seasonal and daily dynamics of seafloor primary production in a shallow New Zealand estuary

Article Title: The breathing seascape: Spatial and temporal up-scaling of an estuarine ecosystem function

Article References: Lohrer, A. M., Stephenson, F., Lam-Gordillo, O., MacDonald, I. T., Massuger, J., Paul-Burke, K., Douglas, E. J., Petersen, G. L., & Bulmer, R. H. (2026). The breathing seascape: Spatial and temporal up-scaling of an estuarine ecosystem function. iScience, 29(10), Article 117597. https://doi.org/10.1016/j.isci.2026.117597

Image Credits: AI Generated

DOI: 10.1016/j.isci.2026.117597

Keywords: estuary, primary production, seagrass, benthic ecosystems, aquatic eddy covariance, Ōhiwa Harbour, New Zealand, ocean darkening, ecosystem services, hypoxia, Māori stewardship, coastal management

The research, led from the Stanford laboratory of biological oceanographer Kevin Arrigo, the Donald and Donald M. Steel Professor in the Stanford Doerr School of Sustainability, draws on an intensive field campaign conducted in the summer of 2023 aboard the research vessel Sikuliaq. The team set out to answer two linked questions: how dense are the phytoplankton blooms that form beneath Arctic sea ice, and what becomes of those blooms when they die? While previous missions have sampled phytoplankton at scattered points in time and space, few have documented the organisms across almost their entire season of growth, from first greening of the water to the final collapse of the bloom.

The story of under-ice phytoplankton blooms begins with a discovery made in 2011, when Arrigo and collaborators reported in Science that phytoplankton were blooming beneath Arctic ice. The observation surprised many researchers, because thick ice had long been assumed to block too much light for photosynthesis. But over the past few decades, Arctic air and sea surface temperatures have climbed, and the ice cover has thinned and cracked, allowing more sunlight to filter through. In the Chukchi Sea, the 2023 measurements suggest that light entering through cracks and thinner patches of ice was sufficient to power substantial photosynthesis in the darker waters below.

The scale of what the team found beneath the ice was remarkable. The researchers observed one of the densest phytoplankton blooms ever recorded, even in areas where the ice was up to two meters thick. These under-ice blooms were up to ten times more concentrated than blooms sampled a month later in open water, after seasonal melting had begun to recede the ice edge. The data show that the blooms eventually withered and began to sink once the phytoplankton had exhausted most of the available nutrients, especially nitrate. As Claudette Proctor, an Earth system science PhD student and lead author of one of the two papers, put it, the organisms are growing in an environment that scientists previously thought was inhospitable.

To follow the bloom through its rise, peak, and decline, the team used a combination of straightforward but demanding methods. They collected seawater samples to measure nutrients and two standard indicators of phytoplankton abundance, carbon and chlorophyll. They also deployed floating sediment traps, moored in the water column both in open water and in holes cut through the ice, to catch phytoplankton as they sank. By tracking how much phytoplankton biomass, by weight, accumulated in the traps over several days, the researchers could estimate both the quantity and the speed of the sinking flux beneath the ice and in open water. They then compared these results with chlorophyll and carbon measured in sediment cores hauled up from the seafloor, connecting the sinking particles to the organic remains accumulating below.

Across much of the Chukchi Sea, the scientists found that phytoplankton sank after their blooms peaked at a rate of about half a meter per day, consistent with expectations for the open ocean. But at particular locations, the sinking accelerated dramatically. Swift waters there pushed the plankton down about four times faster on average, driven by a confluence of ocean currents known as a front. The mechanism is a straightforward consequence of water mass physics: when cold, salty water drifting south just beneath the ice meets warmer, fresher water flowing in the opposite direction in the open water, the denser mass plunges downward, carrying its phytoplankton passengers with it.

James Lauer, an Earth system science PhD student and lead author of the second paper, which focused on how currents affect the blooms, described the encounter in vivid terms: the cold, salty water mass takes a dive, and the warmer, fresher water mass rides up on top. The result is a kind of express elevator to the seafloor for carbon-laden phytoplankton caught at the boundary. Because fronts created by winds, river outflows, or currents are found throughout the oceans, the discovery has implications well beyond the Arctic, suggesting that relatively small-scale physical features may play an outsized role in transporting carbon to the deep sea.

The rapid sinking helps solve an ecological puzzle that has lingered for years. In previous research, scientists had observed areas of the Arctic seafloor supporting unexpectedly high populations of clams and brittle stars, along with the walruses and whales that feed on them, and had struggled to identify the food source sustaining such biomass. The new work provides a plausible answer. As Lauer noted, the discovery that the front is rapidly enhancing rates of sinking helps explain where the food that supports that benthic abundance might be coming from. In effect, the collision of currents is a delivery system that channels surface productivity directly to the animals living in the sediment below.

What happens closer to the surface is less certain, and the timing of the blooms may matter as much as their intensity. Under-ice blooms are a major food source for zooplankton, the tiny drifting animals that in turn feed species such as bowhead whales. But blooms that peak too early in the summer may already be gone by the time seasonal predators arrive, reshuffling who eats what in Arctic food webs. As Proctor suggested, a warmer Arctic could favor bottom-feeding organisms, which benefit from the enhanced rain of sinking food, while pelagic organisms in the water column might face leaner conditions. Such shifts could ripple upward through food webs topped by orcas, whales, and sharks.

The findings also speak to the Arctic’s role in the global carbon cycle. Phytoplankton pull carbon dioxide from the atmosphere as they grow, and the question of what happens to that carbon, whether it is eaten, recycled, or buried in sediments, is central to understanding how the region will respond to climate change. Arrigo said the results point toward an overall increase in the carbon absorbed by phytoplankton and eventually stowed away in sediments, though many unknowns remain. One concern is that warmer freshwater from melting ice could form a buoyant layer at the sea surface, blocking nutrient-rich waters below from mixing upward and thereby limiting future phytoplankton growth. With the Arctic warming four times faster than the global average, the balance between these competing effects will shape how much carbon the fastest-warming region on Earth can lock away.

Subject of Research: The seasonal growth, sinking, and carbon export of under-ice phytoplankton blooms in the Arctic's Chukchi Sea

Article Title: Currents in an Arctic sea accelerate the sinking of carbon-carrying phytoplankton

Article References: Currents in an Arctic sea accelerate the sinking of carbon-carrying phytoplankton. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: phytoplankton, Chukchi Sea, Arctic, ocean currents, carbon cycle, sea ice, fronts, sediment traps, benthic ecosystems, nitrate, climate change, photosynthesis