Assessment of water quality and concentration of heavy metals in fishes in the estuary of the Perizes River, Gulf of Maranhão, Brazil.

The present study evaluated physicochemical and microbiological variables of the water in the estuary of the Perizes River in the state of Maranhão, Brazil, heavy metal levels in the muscle tissue of fish species (Genyatremus luteus, Macrodon ancylodon, Sciades herzbergii and Mugil curema). Data were collected bimonthly between Nov 2017 and May 2018. Physicochemical variables of the water (pH, salinity, conductivity, dissolved oxygen and turbidity). The microbiological analysis of the water was performed using the multiple-tube method. Atomic absorption spectrophotometry was used for the determination of heavy metals in muscle tissue of the fishes. The results revealed minor fluctuations in the environmental variables, with the exception of turbidity. The microbiological quality of the water was associated with acceptable bacterial levels. Regarding heavy metals, acceptable concentrations were found of Al, Cu, Fe, Mn, Zn, Ni and Hg, whereas Cr and Pb were found at concentrations higher than the maximum.