Rhodoliths and Buracas: Expanding Scientific Knowledge in Brazil

Together with scientists from CI-Brazil, local universities, the New England Aquarium and Boston University, CI’s Les Kaufman is exploring Brazil’s Abrolhos Bank to learn more about its marine life and connection to local communities, the impact of climate change and how people can better protect the region. Read his first blog from the trip.

Diver breathing tri-mix (oxygen, helium, nitrogen) inside a buraca at a depth of about 70 meters (230 feet). (Photo courtesy of Dr. Rodrigo Moura)

We have just returned to CI’s office in Bahia from three days at sea, where our team explored the deep, central shelf using technical diving and a remotely operated vehicle (ROV).

This region is a vast carpet of rhodoliths: roughly spherical objects constructed by many layers of hard red algae. Rhodolith fields like this one represent a reservoir of carbon that could play a significant role in regulating global climate — but to know just what that role might be, and how significant a role, we must learn more about them.

Divers brought rhodoliths to the surface from depths of 70 to 80 meters (230 to 262 feet) using a special gas mix that reduces the chances of decompression sickness, also known as “the bends.” When we opened the rhodoliths, we saw that boring by excavating sponges, clams and other organisms is minimal, a sign that the carbon may be stable and not quickly reentering the ocean and the atmosphere.

One scientist on our expedition is studying the creatures that live in and on the rhodoliths, many of which appear to be species that also reside in coral reefs. Other scientists are using the rhodoliths to study changes in ocean and coastal conditions over time.

The other big item bagged in the last few days is a collection of specimens from the buracas: deep holes in the outer Abrolhos Bank. Buracas are often full of fish, so we want to get a better look at their function as “inverted coral reefs” and learn more about how they form.

Today, we head out for another four days of reconnaissance using the ROV — exploring places we still know little about, some of which are in areas where greater protection has been proposed. The weather is promising and our new course is plotted, so out we go for our next Brazilian adventure at sea.

Les Kaufman is a senior marine scientist for CI’s Marine Science program. Stay tuned for updates as his trip continueshis blogs are cross-posted on the New England Aquarium’s Global Explorers blog.

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