I am very lucky to have a guest blog from a good friend and great early career scientist from Brazil, Carla Elliff. Carla is an oceanographer working with Brazilian coral reefs and the ecosystem services they provide. The main goals Carla is striving to reach are to increase ocean conservancy measures, sustainable options and public awareness.
People always talk about how unique coral reefs are as an ecosystem, but sometimes we fail to think how different each reef is to each other. This is particularly true when considering Brazilian coral reefs in comparison to other nations.
Coral reefs in Brazil have four main traits that set them apart from other reefs around the world.
The first are these amazing structures that only occur in the reefs of the Abrolhos bank, called chapeirões. These mushroom-shaped coral pinnacles can reach more than 25 m in height and 50 m in diameter. Why they grow like this and why only in Abrolhos is still quite a mystery.
The second is the low diversity and high endemic rates of these reefs. While coral reefs from the Indo-Pacific Ocean sum hundreds of species, in Brazil there are just under 20 species of reef-building corals. But don’t feel bad for the Brazilian reefs! Although there are few species, the major reef builders are endemic, meaning they only occur in Brazilian waters, which is pretty special. Some of these endemic species have affinities to species in the Caribbean, while others are related to Tertiary coral fauna, which means their closest relatives go way back (between 2.6 and 65 million years) and thus earned them the name of archaic species or relic forms.
The third trait concerns the important role that incrusting coralline algae has in the construction of the reef structure in Brazil. In fact, the only atoll found in the South Atlantic Ocean, called the Rocas Atoll, is basically composed by crustose algae. This has raised much discussion regarding the accuracy of considering Rocas an actual atoll.
Lastly, unlike most reef systems, in Brazil nearshore bank reefs are surrounded and even filled with muddy sediments from the continent. For most coral species this condition would make the waters uninhabitable, however, remember what I said about the endemic species? These species seem to be particularly sturdy and have developed mechanisms to cope with the higher sedimentation rates that can affect turbidity.
Despite these differences, Brazilian reefs also support an immense biodiversity and provide important ecosystem services. Diving in Brazil is definitely a scuba-lover must!