Water Quality Effects on Fish Larvae in a Tropical Coastal Lagoon of the Gulf of Mexico

Abstract

Human settlements and industrial activities located along rivers and coastal lagoon margins have led to the discharge of untreated waste effluents into proximate waters, a situation that has affected the biota, fisheries and man himself. Many examples of this phenomenon exist throughout the world, including along the coast of Mexico. This study analyzed the physicochemical water quality parameters of a coastal lagoon in the northwest Gulf of Mexico during four sampling seasons in 2009 and 2010 that included dry, rainy and north-wind seasons; results were compared to conditions of the lagoon in 1983. Anthropogenic discharges along rivers and lagoons in the study area were correlated with slight increases in ammonium, total nitrogen and phosphorus starting 30 years ago, with concentrations remaining stable during this time period. Intermittent decreases in these nutrients occurred during heavy rains. Residence time of these nutrients varied from 19–40 days and depended on the depth of the lagoon. Results suggest that water quality does not differ greatly between historic and present times, suggesting that these fluvial-lagoon systems do not currently require environmental management. However, controlling urban discharge, as the human population increases will be necessary to minimize the impact of anthropogenic discharges. Fish larvae were only affected by the variation of temperature and salinity of the lagoon water.