Mudanças ambientais e recifes tropicais urbanos: branqueamento de corais resistentes, algas filamentosas e sedimentos

Abstract

Coral reefs, located predominantly in tropical oligotrophic waters with low turbidity are the ecosystem with the highest biodiversity per unit area on Earth. The tidal pool regions, where the coral Siderastrea stellata is commonly found, are environments subjected to higher temperature and salinity rates when compared to values in open sea. This allows tidal pools to be used as a tool to predict future climate change scenarios. The objective of this work is to analyze the benthic components of the healthy coverage of Siderastrea stellata, filamentous algae and ecosystem sediment. Also, it was evaluated the bleaching rates of the colonies and correlate it with physical-chemical factors like temperature and salinity. Samples were collected from october, 2018 to march, 2019 from the Volta da Jurema ferruginous sandstone reef, Meireles. The sampling areas were acquired by delimiting three areas of 36 m² adjacent to each other. Each area was randomly subdivided in four smaller squares (50x50 cm) for the analysis. In laboratory, the programs used for coverage percentage and statistical analysis were photoQuad and PAST, respectively. The results show that the percentage of coverage of ecosystem components, in general, shows no significant difference over months. The temperature shows higher values in october/18, november/18, december/18 and march/19, while the salinity remained with averages above 35 in all months. Bleaching rates were high and they have elevated relationship with temperature and salinity values. Based on these results, it can be concluded that the components of the filamentous algae coverage and sediment ecosystem allowed the occurrence of a selective environment in the Volta da Jurema reef, predominantly for the coral. Siderastrea stellata.