VARIACAO ESPACIAL E INTRA-ANUAL DE FORAMINIFEROS BENTONICOS E INDICADORES BIOGEOQUIMICOS NO ESTUARIO DO REAL, LITORAL NORTE DA BAHIA, BRASIL

Spatial and intra-annual variation of foraminifera and biogeochemical indicators in the Real estuary, northern coast of Bahia, Brazil. The aim of this research was to carry out the biogeochemical characterization of the Real estuary, northern coast of Bahia, using the seasonal variation of foraminifera and physical-chemical, sedimentological, and geochemical data. During the rainy season were obtained 324 foreheads (Jul/2013), with Trochammina inflata in abundance (75.85%). In the April campaign, 298 foraminifera were found in 10 sampling points, especially T. inflata (40.60%), Quinqueloculina lamarckiana (9.73%), Ammonia tepida (8.05%) and Trochammina globigeriniformis (5.70%). In the dry season, 148 foreheads belonging to 14 species were registered, such as Q. lamarckiana (21.19%), Trochammina sp. (10.60%), T. inflata (10.60%), Nonion sinensis (5.96%), Peneroplis proteus (5.96%), and Quinqueloculina bicornis (5.96%). In addition, the faunal composition reflects an environmental condition of high hydrodynamic energy, with clear evidence of oligohaline waters typical of environments with strong river discharges, and absence of anomalies in the foreheads, suggesting an environment without evident anthropogenic changes. The levels of Ca and Al, in both hydrological periods, varied significantly between the sampling stations, but they should not be causing adverse effects on the biota of the Real estuary. The contents of Mg (which come from primary sources) and Fe (which is punctual and seems to be a result of anthropic activity) found are above the reference limits, but does not appear to be causing changes in the balance of the local ecosystem.