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Exploring Exuma’s Oceans

Exploring Exuma’s Oceans

This is the second  part of the story of  “Exploring the Oceans around Exuma”

The M/V Alucia, which is operated by ocean exploration organization OceanX, visited CEI twice. The first mission took place over six days in April 2018 and was a learning experience for the Bahamas-based research team.

“None of us had worked off a sub before, so we didn’t know what it could do,” said Talwar. “We had to deal with simple things like getting our gear to be the right size and the right weight. We tried it out to see what we could actually achieve using the platform, and then we had a few months before they came back to refine what we wanted to do.”

Moored off the Eleuthera coastline, the M/V Alucia attracted a lot of attention, with around 400 visitors touring the boat before the work began. Students from The Island School, an educational facility attached to CEI, and the local Deep Creek Middle School were enthralled by the high-tech vessel, which includes a helipad, fully-equipped science labs and the two manned subs.

Exuma Sound

Even the more experienced members of the faculty were impressed.

“It blew me away,” Talwar said. “The first time I went out to the ship, it seemed unreal. You feel like you are a part of something really big. It was an inspirational experience.”

For that first mission, the team had the choice of two subs – the Nadir, a Triton 3300/3 sub capable of accommodating two passengers and a pilot, and the Deep Rover, a two-seater vessel fitted with a Shilling T4 manipulator, a robotic arm designed for collecting specimens and operating sampling tools. Both subs can descend to 1,000 meters (3,280 feet).

The subs explored the rocky terrain of the Exuma Sound, which includes a vertical wall that descends down 200 meters (656 feet) and ends in a steep slope marked with boulders, rock falls and ridges.

It was otherworldly, according to Talwar. “There are incredible ridges that come out of the shallow water embankment and run down to 800 meters (2,624 feet),” he said. “Going over that in a sub feels like you are flying over a mountain range.”

Submarine photo in Exuma Sound

It took around 30 minutes to fully descend in the sub. “The light changes as you go down. You see purple, dark blues and then black” Talwar said. “There is a bioluminescence layer, and if you turn off the lights you can see these little fireworks going off. It is beautiful and incredibly peaceful.”

Between 300 meters (984 feet) and 500 meters (1,640 feet), on the edge of the Exuma Sound wall, the team found various species of echinoderms (starfish, sea urchins, and sea cucumbers) and a previously undocumented species of glass sponge. They also collected samples of sea cucumbers and crinoids at 630 meters (2,066 feet).

Tagging, monitoring and observing

Although it is too early to tell if the samples they collected are new species, Talwar is hopeful, saying: “We pulled up a number of invertebrates. We saw all kind of things, it just takes time to identify them. I would be very shocked if we did not find any new species.”

Alongside samples, the team collected valuable footage of life on the ocean floor. They rigged up bait boxes with cameras on timers, synced with lights, to capture deep-dwelling fish such as night sharks.

photos at 2000 ft
Cameras attached to bait boxes monitored marine life in the deep ocean. Image courtesy of The Island School

Dr. Dean Grubbs from Florida State University, which partnered with CEI on the mission, led efforts to tag a notoriously elusive deep-water predator, the bluntnose sixgill shark.

The sixgill is one of the oldest sharks in the ocean but learning more about the species has proved difficult. Tagging a sixgill shark usually involves dragging it up to the surface, putting the animal under extreme stress.

six gill shark off Exuma

Part 3 of this story will follow shortly.
story copied with author’s permission from https://news.mongabay.com

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