PARENT SESSION
MP2 - Aquatic Toxicology
Chair: Spehar, Bob¹, ¹ U.S. EPA, Duluth, MN
Co-chair: Henry, Mary², ² U.S. Fish and Wildlife Service, Arlington, VA
2:10 PM to 5:30 PM - Monday, 18 November 2002
Room Ballroom J

(261) Effects of pollutants on histological lesions in fish from three lakes in Chiapas, Mexico.

Gold-Bouchot, Gerardo^*,1, Simá-Alvarez, Raul¹, Ceja-Moreno, Victor¹, Del Rio-Garcia, Marcela¹, Medina-Elizalde, Martin, Pascual-Barrera, Alina¹, ¹ Cinvestav Unidad Merida, Merida, Yucatan, Mexico

ABSTRACT- The Mexican states of Tabasco, and the northern part of Chiapas, are oil producing zones, representing around 20 % of Mexico's domestic production. As part of an environmental evaluation, water, sediment and 46 tilapias were collected in three lakes (Laguna Limon, de En Medio and del Rio) in Chiapas. Samples were collected during the rainy season, water level was high and the lakes were joined together. Pollutants (hydrocarbons, organochlorine pesticides, PCBs and metals) were analyzed in sediments, water and tilapia livers. Additionally, histopathological lesions were determined in liver, gills, gonads and kidney. Concentrations of total hydrocarbons in sediments were high (5353, 478.5 and 478.2 g/g) , and there is a significant relationship between total hydrocarbons, chromium and copper in sediments with distance to a combined discharge from a petrochemical plant, suggesting that it is the main input of pollutants to the lakes. Low molecular weight PAH metabolites had higher concentrations than high molecular weight metabolites in bile, suggesting a petrogenic origin of the hydrocarbons. A Redundancy Analysis, the canonical form of Principal Component Analysis, of the histological lesions (corrected for sampling site and fish length), accounted for 43% of total variance. Explanatory variables were OH-fenanthrene in bile, and chlordanes and pentachloroanisole in liver. The analysis was highly significative (P=0.0044). There is strong evidence that contaminants are producing the observed lesions in tilapias, and that the main source is the petrochemical complex, and thus there is cause for concern for the health of these ecosystems.

Key words: Histopathology, Tilapia, RDA