Written by Carla Elliff
As 2018 was coming to a close, a group of Brazilian researchers published a ground-breaking study describing an entirely unknown coral reef system. This was a large collaboration among the Federal University of São Paulo (Unifesp), the University of São Paulo (USP), the Federal University of Rio de Janeiro (UFRJ), the Federal University of ABC (UFABC), the Federal Rural University of Rio de Janeiro (UFRRJ), the Laje Viva Institute, and the Botanical Garden of Rio de Janeiro.
As if the discovery itself wasn’t amazing enough, the location where it was described changed what we thought we knew about coral reef distribution!
Fringing the Queimada Grande Island, located in the state of São Paulo, Brazil, at latitude 24°29’S this is now the most southern coral reef ever described in the Atlantic Ocean. This places the austral limit of reef distribution nearly 1,000 km away from the largest coralline reef system of the Southwestern Atlantic: the Abrolhos Bank (between 16°50’S and 19°40’S).
Brazilian coral reefs have very low species diversity, reaching a maximum of only 20 species in the richest spots of Abrolhos. The Queimada Grande Island coral reef is not different and is in fact composed of only two species: Madracis decactis and Mussismilia hispida. Though the number of species is not surprising, having M. decactis reported as the main framework builder of the reef is a first-time occurrence! This species is usually observed forming patches over other substrates or as a free-living coral (a corallith) and it is not very resistant to high sedimentation and temperature extremes.
Moreover, this fringing coral reef occurs in association with an impressive rhodolith bed. Rhodoliths are a type of red algae that grows covering rocks and other substrates, creating a carbonate crust. They look like corals and can support a wide range of living organisms. However, different from corals, they rely solely on photosynthesis for energy and can be found in very cold waters, such as in Greenland.
Dr. Guilherme Pereira-Filho is the lead author on this publication and, together with his co-authors, described that one of the reasons why this coral reef went unnoticed for so long is because the detection of underwater structures in this region relies heavily on in situ observations. The application of remote sensing techniques, such as satellite images, is very limited due to the relatively murky waters of southeastern Brazil, which receive large freshwater inputs from adjacent rivers (rainfall rates up to 4,000 mm/year).
The Queimada Grande Island has been a natural laboratory studied by scientists for decades. It is internationally known as Snake Island, with an estimated 55 snakes per hectare. Moreover, commercial and recreational fishermen have been enjoying the ecosystem’s abundant resources for many years. Perhaps a citizen science initiative with people going out there for spearfishing would have allowed this discovery to happen sooner!
Dr. Pereira-Filho and his co-authors now hope that this coral reef will strengthen current conservation efforts and policy improvement for the island and surrounding area.
You can find the original scientific article here: http://www.unifesp.br/campus/san7/images/Pereira-Filho_etal_2019__The_southernmost_Atlantic_Coral_Reef_-.pdf
For more images and information on the newly discovered southernmost coral reef in the Atlantic, check out this video made by the researchers involved in the discovery:
Also, if you’d like to read more about Brazilian coral reefs, have a look at a previous post of mine called “Brazilian coral reefs and their ‘jeitinho”!