Algal blooms and trophic state in a tropical estuary blocked by a dam (northeastern Brazil)

The Bacanga River Estuary is socioeconomically important due to artisanal fishing and aquaculture. It blocked by a dam under human pressure along its drainage basin, intensifying the eutrophication process. This study reports on occurrence of phytoplankton blooms trophic state (TSI TRIX) at six sampling sites during annual cycle. estuary was divided into downstream upstream regions. Higher salinity, turbidity, depth, lower dissolved oxygen levels were found downstream; whereas, high chlorophyll nutrient concentrations observed in both There Leptocylindrus danicus (1.45 × 106 cells L-1) Skeletonema costatum (1.89 whereas phytoflagellate proliferation, such as those Chlamydomonas sp. (13.17 L-1), Euglena gracilis (7.84 proxima (1.03 recorded upstream, with discriminant species this zone. Both indices (TSI; indicated elevated conditions for estuary, classifying it hypereutrophic. Nevertheless, TSI only showed significant relationship some specific blooms. Thus, seems be index better response assessment estuarine ecological functioning.