Environmental conditions and pesticide pollution of two coastal ecosystems in the Gulf of California, Mexico.

In December 1997 and April and September 1998, water temperature, salinity, dissolved oxygen, nutrients, chlorophyll, and pesticide residues were determined in two coastal ecosystems of Sinaloa, NW Mexico: Ensenada del Pabellón and Bahía de Santa María. These two are considered to be among the greatest shrimp producers in the region. Temperature, salinity, and dissolved oxygen were similar to those of other ecosystems of this region: high temperatures and salinity in spring and summer (dry season) and lower in winter and the rainy season. Levels of nitrites and phosphates and chlorophyll concentration were relatively higher than those of other ecosystems nearby, probably due to fertilizers used in the agricultural lands surrounding the water bodies studied. The pesticides more frequently detected were BHCalpha, aldrin, endosulfan and parathion. In some cases, pesticides forbidden by Mexican regulations were detected. These results indicate that the ecosystems studied are in a warning condition, because severe biochemical and physiological alterations have been reported in crustaceans exposed to pesticides. Therefore these pesticides could be one cause of the slow growth, diverse pathologies, and mortality in shrimp that have been reported in recent years. Copyright 1999 Academic Press.