RESUMO
Tropical estuaries are productive dynamic ecosystems where water quality is mediated by physicochemical and biological processes and by fluvial and anthropogenic discharges. The objective of the study was to determine the influence of environmental variables on the spatiotemporal dynamics of water quality in Buenaventura Bay, which is a highly impacted estuary. Sampling was carried out during the dry and rainy season, at three depths, in four stations that represent the environmental gradient of the bay. Temperature, total dissolved solids, salinity, dissolved oxygen, and pH were determined for each sample. In addition, alkalinity, phosphates, nitrites, and nitrates as indicators of water quality were also measured. The estuary was classified as meso- and polyhaline, with appropriate oxygen and pH conditions and spatiotemporal gradients of temperature and solids mediated by river discharges. Significant variations were found in the physicochemical variables by season, with maximum salinity, pH, and solids in the dry season and oxygen and temperature in the rainy season. Likewise, most of these environmental variables were higher in the outer zone of the estuary and lower in the inner stations. Alkalinity and nitrite values were within the permitted ranges, while phosphates and nitrates indicated low water quality. There was a significant direct influence of temperature and oxygen on alkalinity and nitrites. However, for phosphates, no significant influence of environmental variables was found, suggesting a greater influence by fluvial and anthropogenic discharges, which produce a decrease in the environmental quality of the estuary.