Ocean Literacy · Deep Sea Exploration

A Country Looks Into Its Own Deep Sea for the First Time

Twenty-five cold seeps, twenty suspected new species and more than 11,000 square kilometres of newly mapped seafloor. Trinidad and Tobago has surveyed the deep half of its own territory, led by its own scientists, and come back with a photographic record of a place almost nobody had seen.

By SEVENSEAS Media | Ocean Conservation

Most of Trinidad and Tobago is out of reach. Ninety-three per cent of the country’s marine jurisdiction lies below the depths a recreational diver can reach, which means the largest ecosystems the two islands own have never been visited by the people who own them. In July, for the first time, a team led by Trinbagonian scientists went down to look.

The month-long expedition, called Deep Wonders of Trinidad and Tobago, ran aboard Schmidt Ocean Institute’s research vessel Falkor (too) under chief scientist Dr Diva Amon of the non-profit SpeSeas. By the time the ship came home the team had mapped over 11,335 square kilometres of previously uncharted seafloor, roughly 13 per cent of the national marine territory, located 219 bubble streams, visually confirmed 25 cold seep ecosystems, collected more than 700 specimens and photographed at least 54 species never before recorded in the country’s waters.

A country mostly out of reach

The geology helps explain why the expedition expected to find something. The two islands sit on a continental shelf edge where methane and hydrogen sulphide leak from the sediment, and that setting supports chemosynthetic habitats: communities that run on chemical energy rather than sunlight. Schmidt Ocean Institute puts the proportion of the country’s deep-ocean territory previously explored at less than 0.001 per cent, a figure whose basis is not stated in the material released, but which points the same way as everything else here.

Setting out

The expedition sailed on 29 June. Among the equipment aboard was DORIS, the Deep Ocean Research and Imaging System, an experimental low-cost deep-sea camera developed by the Ocean Discovery League and Blue Robotics and designed to make deep-ocean imaging affordable enough to be used widely. Schmidt Ocean Institute states that Trinidad and Tobago became the first country to deploy it successfully, at depths between 900 and 2,238 metres.

Twenty-five seeps

The mapping data gave the team 219 bubble streams to investigate, each a possible cold seep. Working through them with the remotely operated vehicle SuBastian, they confirmed twenty-five. The largest covers about half an acre, less than a third of a World Cup football pitch, and is carpeted in mussels and tubeworms. These are ecosystems assembled around leaking gas rather than sunlight, and the animals that live at them are found nowhere else on the slope.

What may be new

Twenty species are suspected to be new to science, three of them possibly new genera. That is a claim awaiting formal description, not a settled count, and it is worth being precise about what the photographs show: of the twenty-six frames in this article, only two are stated by the expedition to depict a suspected new species. The octopus at the top of this page is one. The carnivorous sponge below is the other. The rest are animals and habitats newly recorded in these waters, which is a different and still substantial thing.

As the first locally led deep-sea expedition in Trinidad and Tobago’s history, these discoveries are proof that Caribbean scientists can uncover our own deep-sea backyard.

Dr Diva Amon, chief scientist, SpeSeas

Coral as architecture

Cold-water corals do not get the attention their shallow relatives do, and they are more abundant. On this slope a single colony works as shelter and feeding ground for a crowd of other animals: squat lobsters, brittle stars, shrimp and fish, all of them living on a structure that took centuries to grow. Four frames from consecutive dives, within about a hundred metres of depth of one another, show the same relationship from different angles.

Encounters

Some of what the vehicle found was simply rare to witness. A dead manta ray on the seafloor at 1,025 metres, being taken apart by crabs and worms, is a windfall in an environment where food arrives seldom and unpredictably. A black swallower with a visibly distended belly is a fish that has eaten something larger than itself, which is the ordinary way that species feeds. A false catshark, three metres of slow and soft-bodied shark, drifts past the lights.

Shallower ground

Not all of it was deep. Late in the expedition the vehicle worked a slope inside a UNESCO Biosphere Reserve at 148 metres, in the mesophotic zone that the eelpout caption defines as running from 30 to 199 metres. This is the shallow end of the country’s unexplored half, close enough to shore to matter directly to fisheries and to any future protected area, and still below the depth at which anyone can casually go and look.

The work aboard

None of these photographs exist without the machine that took them. SuBastian is depth-rated to 4,500 metres, which puts the deepest frame in this article, the chimaera at 2,355 metres, at roughly half the vehicle’s reach. It goes down on an umbilical, works a dive, and comes back over the stern on an A-frame, and then the day’s real work starts.

Over 700 specimens came aboard across the month. All of them will be held at the Zoology Museum at the University of the West Indies, St Augustine, increasing that museum’s deep-sea collection twelve-fold. Several of the people photographed handling those specimens at sea are graduate students at the same university that will keep them, which is the practical shape of what “locally led” means.

A frozen zoo

The expedition also trialled a cryoprotectant that freezes living tissue at minus twenty degrees without the cell damage associated with liquid nitrogen. The team reports cryopreserving tissue from more than 86 species of deep-water sponges, corals and sea cucumbers, which they describe as the first “frozen zoo” in the Caribbean. Whether the method validates as a standard for cryobanking marine invertebrates is a question for the published results rather than the press release.

By cryopreserving tissues from more than 86 species of deep-water sponges, corals, and sea cucumbers, we’re preserving living biological resources that provide an invaluable baseline for understanding future ecosystem change.

Dr Megan Conkling, Harbor Branch Oceanographic Institute, Florida Atlantic University

Watching from a dark room

Every frame in this article was chosen in real time by people sitting in a windowless room watching a live feed, deciding where the vehicle should go next and when to stop and collect. It is worth noticing who was in that room. Alongside the biologists was a geoscientist, which is the only visible sign in this material that the expedition was also doing the geology, the heatflow and mud volcanoes and the physical mechanics of the seeps themselves.

What the data is for

Amon has said the mapping and biological data will feed marine governance and spatial planning in Trinidad and Tobago, including the designation of marine protected areas. That is the part that has not happened yet. A survey produces a baseline; whether the baseline becomes protection is a political question rather than a scientific one, and the expedition has no power over it. What the team can say is that the country now has a first description of the ecosystems in question, which it did not have in June.

The expedition also found rubbish. Among the seeps and the coral gardens, in places no person had ever visited, there was human-made debris on the seafloor. Amon has noted it as a reminder that absence of visitors is not absence of impact.

Alongside the science, the team ran a public engagement programme, reaching more than 2,000 people through Schmidt Ocean Institute’s Ship-to-Shore live link and over 1,000 more through school and university visits before sailing. For a country where almost nobody has seen the deep half of their own territory, showing it may turn out to matter as much as mapping it.

Read the full announcement from Schmidt Ocean Institute: First Caribbean-Led Expedition to Explore Trinidad and Tobago’s Deep Sea Unveils Rich Ecosystems. All photographs in this article are reproduced with credit under the terms supplied by Schmidt Ocean Institute; captions are the expedition’s own.

SEVENSEAS Media · Conservation Journalism for the Ocean