27 Mar 2014
Exploring Little Known Habitats Off the Brazilian Coast
Introduction written by the Ocean Health Index
The Abrolhos region occupies about 95,000 sq km (37,000 sq mi) off the Brazilian state of Bahia and is the most biodiverse realm in the South Atlantic Ocean. It provides numerous ocean benefits to Brazilians and tourists and contributes to Ocean Health Index scores for goals such as Biodiversity, Tourism & Recreation, Sense of Place, Coastal Protection, and Carbon Storage.
We highlight Abrolhos in the story below by Boston University scientist, Les Kaufman, a member of a team that is discovering novel facets of this seascape that are more important than we ever knew.
This article originally appeared on Conservation International's HumanNature blog on March 26, 2012.
After a blessedly uneventful flight to Miami, and then Salvador, and finally Porto Seguro, our drive traverses the landward side of our study area, sometimes known as Brazil’s Discovery Coast. This region was “discovered” by Pedro Alvarez Cabral in 1500 — only about 2,000 years after being discovered by the people who actually lived there.
This landscape was once carpeted by the majestic Atlantic Forest, largely replaced today by cattle ranches and eucalyptus plantations.
It is also a place of vast lowland habitats called restinga, a mix of dunes, mangroves, scrub, forest, wetlands — and people who are experts at eking out a living in this challenging but stunningly beautiful ecological landscape. Restinga vegetation is an odd mix of strange elements, including riverine wetlands dominated by bromeliads, which are relatives of the pineapple.
I am here to join my Brazilian colleagues in a study of the Abrolhos Bank, a shallow shelf that contains the most species-rich coral reefs in the South Atlantic. Our goal is to learn more about the marine life of Abrolhos and its links with communities; how both are likely to be affected by global climate change; and what people can do to limit the bad and maximize the good in light of our own explosive growth in numbers, affluence and technology.
Abrolhos is a large area off the coast of northeastern Brazil, well south of the Amazon River mouth. This roughly circular ledge of continental shelf projects out about 120 miles [193 kilometers] to the east of the scenic beaches of Bahia. It is a magnet for whale-watchers, divers, sport fishermen and vacationers, and home to the lion’s share of the coral reefs in all the South Atlantic.
The Brazilian marine team — made up of scientists from local universities and Conservation International — has made astonishing discoveries out here, many assisted by a side-scan sonar survey conducted a couple of years ago.
On this expedition, we are exploring exciting, little-known marine habitats in several ways:
- With regular scuba diving, down to a maximum depth of about 120 feet (37 meters);
- With deeper technical diving that uses special mixed gases, allowing the diver to descent to about 250 feet (76 meters);
- With high-definition video cameras on cables; and
- With a remotely operated vehicle (ROV), a sort of robot on a cable that can be steered around underwater.
But to me, the habitats are more exciting than the technology. First are the newly discovered deep reefs. Among these reefs we discovered vast fields of something called a rhodolith: a ball made out of layers of red algae that form a hard skeleton, similar to that of coral. Each is about the size of a softball, and can be anywhere from around 300 to 8,000 years old. These algae balls are piled many centuries deep, and only the ones on the top and sides are still alive.
The Abrolhos rhodoliths could be one of the world’s largest stores of what we call “blue carbon” — carbon absorbed and stored by coastal ecosystems like mangroves, salt marshes and seagrass beds that helps to mitigate climate change.
Another newly-discovered habitat is called a buraca — basically a vertical hole or shaft going straight down into the shelf. There are lots of these holes, and one of the things we’ve found inside them is big schools of young fish.
This discovery was a big deal; these are the young of commercially important species such as snappers. Previously we had only the vaguest idea where all these baby fish were coming from — certainly not the stork! By examining the layers along the buracas’ exposed walls, we may also get greater insight into the history of the shelf.
The expedition will take place in several legs, each a few days long. Last night we had a lovely dinner of drum fish and peas below a powerfully full moon. Land crabbers moved systematically up and down the beach in search of their quarry, one with a horse-drawn cart. Children wheeled and played in lunar luminescence to the lulling sound of lapping wavelets. We talked about fish, birds and whales deep into the night.