CARACTERIZAÇÃO DA ASSEMBLEIA DE FORAMINÍFEROS BENTÔNICOS NO PARQUE ESTADUAL MARINHO DA PEDRA DA RISCA DO MEIO (CEARÁ, BRASIL) E SEU USO COMO INDICADOR DE CONDIÇÕES DE ESTRESSE EM RECIFES DE CORAIS

Characterization of the benthonic foraminifera assembly in the Pedra da Risca do Meio Marine State Park (Ceará, Brazil) and its use as an indicator of stress conditions in coral reefs

Abstract

Foraminifera are abundant organisms in marine sediment, divided into benthic and planktonic forms, whose shells are easily preserved in the substrate and can act as a great key for ecological and paleoecological studies. In coral reef environments, some species of benthic foraminifera can host endosymbionts with demands similar to those of corals in terms of physical and chemical conditions. The main objective of this study was to identify the main assembly of benthic foraminifera present in a coral reef environment in order to determine the FORAM index (FI), a simple, non-invasive indicator whose function is to determine whether the quality of the water in the environment is favorable to the growth or recovery of coral reefs, monitoring the stress conditions of that location by using benthic foraminifera as bioindicators. Three samples were taken at one point in the Pedra da Risca do Meio Marine State Park (PEMPRIM), where the top three centimeters of sediment were sampled. The samples were washed and quartered for sorting under compound microscope, with identification at the genus level and determination of the calcium carbonate level. The assemblage proved to be uniform and highly diverse, with the genera Quinqueloculina, Amphistegina, Elphidium and Rosalina, characteristic of salty waters with low continental influence, being the most abundant. The calcium carbonate level indicated a predominance of bioclastic sands and the FI showed an average value of 3.2, that indicated a favorable environment for coral growth and development, but not ideal for recovery, which would be 4 or above. Similar values were observed in Porto Seguro and Tamandaré, indicating that there may be a potential stress in the waters of the only marine park in the state of Ceará, as well as in these locations.

Keywords: Symbiont bearing foraminifera; FORAM index; Water quality; Bioindicators; Coastal reefs.