Comunidade fitoplanctônica e qualidade da água na Praia de Barreiras, em Icapuí (Ceará/Brasil)

Abstract

The phytoplankton is an important primary producer and forms a community mainly composed of unicellular algae, playing a fundamental role in the food chain, in balancing the carbon cycle, and in preserving water quality. Thus, the aim of the study was to verify the composition of the phytoplankton community and the presence of water quality bioindicators at Ideal Beach. Monthly collections were conducted between February and October 2023, filtering 100 liters of water in each sample using a mesh aperture of 25 μm and a mouth diameter of 25 cm. The collected material was concentrated to 10 mL, fixed in 4% formaldehyde at a 1:1 ratio, and 10 subsamples of 0.1 mL were analyzed using a Callmex® microscope. In situ data on water temperature, transparency, salinity, pH, dissolved oxygen, ammonia content, and phosphate were obtained. Regarding the phytoplankton community, the presence of Oscillatoria sp. was very abundant, in addition to Planktothrix sp, Oedogonium sp, Licmophora sp, Ciclotella sp, Triceratium sp. The trophic state index (TSI) for Barreiras Beach shows eutrophic conditions, having incidence of bioindicators of eutrophic and/or polluted waters (Oscillatoria sp, Planktothrix sp. and Triceratium sp.)..