Type-e Botulism In Lake Erie
Lake Erie has recently been the site of botulism type E outbreaks that have affected fish, waterfowl and mudpuppies. These epizootics were caused by a paralytic neurotoxin produced by the bacterium Clostridium botulinum type E. In our previous work, we found genetic evidence of C. botulinum type E in sediment as well as in dreissenid mussels, amphipods, oligochaetes and chironomids collected from Lake Erie. This evidence strongly suggests that aquatic invertebrates are links in the transmission of the toxin from the benthic food web compartment to higher trophic levels such as fish and birds. Continuing research is aimed at gaining a better understanding of the conditions that lead to growth of this bacterium and identification of pathways of bacterial toxin transmission.
Disposition and Metabolism of 2,4,2’4’ tetrabromodiphenyl ether (BDE-47) in Rainbow Trout
Polybrominated diphenyl ethers, PBDEs, are an emerging environmental issue of concern. They are ubiquitous in the environment and levels in humans have increased by a factor of ~100 during the last 30 years. In New York, for example, PBDEs levels of at 135 parts per billion fat were found in breast milk. PBDEs can disrupt thyroid hormone balance, impair neural development, and impair immune response, especially during fetal and neonatal development in both humans, other mammals, and fish. In the Great Lakes, PBDEs have been detected in fish from all trophic levels, and their concentration in Great Lakes fish is doubling every three to four years, even though other toxics like PCBs and mercury are declining. In this experiment, trout were fed corn contaminated with BDE-47, and there tissues were analyzed for amounts of the original material and for any possible contaminants. These analyses showed that there was initial movement of BDE-47 from the stomach to the intestine and muscle tissue, with concentrations peaking at one week. Concentrations in adipose tissue started to increase in four weeks and was still accumulating after 10 weeks. No metabolites were detected in fish tissues during this study. However, consumption of contaminated tissue by higher vertebrates may form the basis for endocrine disruption due to subsequent metabolism by the consumer.
Estrogen mimic substances in Lake Erie
Endocrine-disrupting compounds, ranging from natural estrogens to industrial chemicals (PCBs and PBDEs) enter the Great Lakes and their tributaries through discharge of municipal wastewater treatment plants (WWTPs), industrial wastes, and agricultural drainage. Elevated levels of these compounds in aquatic systems affect fish and other organisms through their effect as endocrine regulators. The presence of estrogens in lakes has been linked to feminization of male fish, reproductive failure, and collapse of the fish population. This on-going project aims to determine the occurrence of estrogens of anthropogenic origin/activities in male fish of selected eastern Lake Erie species.
