The aim of this wat was to evaluate the water quality in four tidal creeks of Paraná, Brazil, with different anthropic influences. Samples were collected every three months. Temperature, salinity, pH, alkalinity, total CO2, dissolved O2, nitrite, nitrate, N-ammoniacal, phosphate, silicate, particulate suspended matter, humic matter, total chlorophyll, total and fecal coliform bacteria of surface water were measured in each sample and compared. For all the stations water temperature was lower in winter, but ranged within typically subtropical values. Salinity (7 - 25) and pH (7.08 - 7.91) were higher in Perequê tidal creek indicating that only this tidal creek was strongly influenced by the nearby ocean waters. Lower dissolved O2, reaching anoxic levels along with higher phosphate and N-ammoniacal concentrations and higher total (<200 - 160,000 MPN 100 ml-1) and thermotolerant coliforms (<200 - 50,000 MPN 100 ml-1) in Olho d´Água suggested euthrophication, especially in summer when rainfall was higher and tourism was at its peak. Perequê, Penedo and Barranco Creeks were characterized as meso- and oligotrophic environments.
tidal creek; eutrophication; coast of Paraná
