Scleractinian corals (Cnidaria: Anthozoa) from reef ecosystems on the Alagoas coast, Brazil

The distribution and ecology of scleractinian corals on reef ecosystems along the coast of the State of Alagoas, north-east Brazil, were characterized. The scleractinians comprised 13 species in nine families, with five endemic corals, on the Alagoas coast. All of these species were found on reef ecosystems of two distinct geological origins. Coral reefs are predominant on the northern and central coast with banks near the beach line and distributed along the coast line, with many platform surfaces emerging during low tide. Sandstone reefs are more common along the south coast of Maceio city and the southern coast of Alagoas. These reefs were formed by old sand banks solidified through sedimentation starting from chemical reactions with calcium carbonate or iron oxide from the Quaternary period, and are generally in rows parallel to the coastline and near the outlets of rivers and estuaries. A few species including Favia gravida and Siderastrea stellata were found in the intertidal zone on top of the reef platform of both types of reefs. The other scleractinian species were observed on the reef borders where there were some inlets and channels. A larger number of coral species occur on the northern coast where the seawater is clearer throughout the year.