Victor Ceja-Moreno

Biomarkers and pollutants in the Nile Tilapia, Oreochromis niloticus, in four lakes from San Miguel, Chiapas, Mexico

The effects of the oil industry and environmental pollutants present in four lakes from Reforma, Chiapas, Mexico, were assessed via ethoxyresorufin O-deethylase activity (EROD), PAH metabolites, and butyrylcholinesterase activity (BChE) in Nile Tilapia, Oreochromis niloticus. Fish were collected during two seasons (the rainy season in September 2000 and the dry season in May 2002) from the lakes Caracol, Rio, Enmedio, and Limon. Fish were sacrificed and EROD activities, hydrocarbons, organochlorine pesticide and heavy metal concentrations were determined in the liver, while PAH metabolites and cholinesterase activity were measured in bile and muscle, respectively. Hydrocarbon concentrations in fish liver were moderately high, as compared with results reported for the other species in different coastal ecosystems in Mexico. The highest concentrations of total hydrocarbons were found in fish captured in Lake Limon, and the lowest in Lake Caracol. The highest EROD and PAH metabolites were found in fish collected from Limon and Enmedio lakes. A Spearman test showed significant negative correlations between EROD and BChE activity with fish weight. EROD correlated with total hydrocarbons, the metabolites of pyrene and benzo[a]pyrene, and negatively with polychlorinated biphenyls (PCBs), endosulphan, hexachlorobenzene (HCB), and pentachloroanisol. BChE activity in the four lakes was lower than the activity measured in laboratory cultured tilapias, indicating the presence of anti-cholinergic pollutants in the area; Caracol was the lake with the lowest enzyme activity. This study demonstrated that high concentrations of contaminants can cause effects on fish metabolism, and that tilapia can be used as a test organism in tropical ecosystems.

Biological effects of environmental pollutants in American Oyster, Crassostrea virginica: a field study in Laguna de Terminos, Mexico

The response of Crassostrea virginica to a complex mixture of toxic contaminants was studied at four sites in Laguna de Terminos, Mexico. Contaminants assessed were heavy metals, organochlorine compounds, and hydrocarbons. Biomarkers (cholinesterase activity, neutral red retention, and metallothionein), histopathology and prevalence of Perkinsus marinus were used to evaluate the effects of contaminants. The resultant contaminant body burden was moderately as high as a whole, and biomarker levels were also moderate. Oedema in the gills and systemic haemocytosis were the only histopathological lesions observed. P. marinus was never evidenced in the oyster tissues examined. Statistical results from principal components analysis show that metallothioneins are positively correlated with copper and chromium, neutral red and oedema with chlordanes, pentachloroanisol, drins, polychlorobiphenyls and total pesticides, total hydrocarbons and polycyclic aromatic hydrocarbons, whereas cholinesterase activity is negatively correlated to Cu and Cr. The biomarkers used were sensitive indicators responding to moderate levels of pollutants.

Vitellogenin Induction and Increased Plasma 17β-Estradiol Concentrations in Male Nile Tilapia, Oreochromis niloticus, Exposed to Organochlorine Pollutants and Polycyclic Aromatics Hydrocarbons

Vitellogenin (Vtg), 17β-estradiol (E2) and testosterone (T) were used as biomarkers of endocrine disruption in mature male nile tilapia (Oreochromis niloticus) from three lakes (Rio, Enmedio and Limon) in Chiapas, Mexico. Vitellogenesis induction was found in tilapias from Rio and Limon, moderately high E2 levels in Rio and Limon tilapias, compared with controls (cultured tilapias). Significant correlations between benzo(a)pyrene (BaP) metabolites and hexachlorobenzene (HCB) with Vtg and E2 were found. The results of this study indicate that endocrine disruption exists in tilapias from Rio and Limon lakes, and that exposure to HCB and BaP could be causing these alterations.

Ecotoxicological effects of POPs on ariidae Ariopsis felis (Linnaeus, 1766) from three coastal ecosystems in the Southern Gulf of Mexico and Yucatan Peninsula

Persistent Organic Pollutants (POPs) are still used for agricultural and disease vector control, as well as for industrial purposes. In the last decades, various studies have shown that fish are sensitive to the toxicological effects of certain POPs, including a large class of endocrine- disrupting chemicals (EDCs). In the present study, the relationship between of POPs and their effects using vitellogenin gene expression as biomarker of effect in hardhead catfish Ariopsis felis (Linnaeus, 1766) from three ecosystems in the Southern Gulf of Mexico and Yucatan Peninsula are discussed. Contaminant results showed that median concentrations of PCBs, HCHs, DDTs and Chlordanes were higher in Laguna de Terminos with respect to Celestun and Dzilam. In the same way, the vitellogenin gene expression was clearly over-expressed in fish collected from Terminos Lagoon. Principal Component Analysis showed that vitellogenin gene expression is related to the concentrations of total DDTs and PCBs, and negatively related to total Drins. Overall, this study represents the first tests exploring changes in molecular diagnostic indicators following exposure of several organic compounds in our country. Vitellogenin gene expressions associated with some endocrine disruptors detected in Terminos Lagoon were measured and we can now report clear changes in fish exposed.