Spatial heterogeneity of zooplankton community in an eutrophicated tropical estuary

Studies on the zooplankton community are essential for diagnosing the health of aquatic ecosystems, as these systems respond quickly to environmental changes. Using the multimetric TRIX index for the assessment of trophic status, we assessed the trophic state and its association with zooplankton composition, distribution, and environmental variables in a tropical estuary on the Brazilian equatorial margin. The results showed that significant seasonal and sectoral environmental differences contributed to biological heterogeneity, with the second spatial sector (SII) exhibiting the greatest impact, leading to decreased alpha diversity compared to that of the first spatial sector (SI). Salinity, pH, SiO 2 3 , and NO 2 − exhibited significant seasonal and sectoral variations ( p