The Problem:
Our project examines the effects estrogenic pollutants have on the reproductive health of largemouth bass. In particular, we are looking at the effects contaminants in poultry litter have on gonadal development and morphology in male largemouth bass resident in Chesapeake Bay tributaries.
The formation of testicular oocytes (TO) and the production of a female egg yolk protein, called vitellogenin (Vtg), in male fish of multiple species have been reported with increasing frequency from around the globe. Likewise, prevalence of TO and Vtg in male fish has, in numerous instances, been correlated with pollution from various sources including wastewater discharges and intensive agricultural runoff. Such evidence of anomalous reproductive physiology and development, termed endocrine disruption, may be symptomatic of serious reductions in reproductive competence and ultimately promote population declines.
Such population declines are occurring in smallmouth bass within the Potomac and Shenandoah River systems and are coincident with high prevalences of TO suggesting a possible link to contaminants entering these systems. One emerging source of contaminants comes from the rapidly growing regional Virginia, West Virginia, and Western Maryland poultry industry which allows runoff of poultry litter-associated contaminants into receiving water following crop and pasture-land application. Similarly, the Eastern Shore of Maryland, Delaware, and Virginia has a substantial and long-established poultry industry producing approximately 700 million kilograms of poultry litter annually, most of which is land applied as fertilizer. Despite the abundance of poultry litter in the region and substantial increases in land application over recent decades, no comprehensive analysis of the influence of poultry litter on resident fish has been undertaken. Given the ecological and economic importance of smallmouth and largemouth bass as keystone predators within regional aquatic food webs, any effects poultry litter might have on bass reproduction are important to residents of Maryland.
The formation of testicular oocytes (TO) and the production of a female egg yolk protein, called vitellogenin (Vtg), in male fish of multiple species have been reported with increasing frequency from around the globe. Likewise, prevalence of TO and Vtg in male fish has, in numerous instances, been correlated with pollution from various sources including wastewater discharges and intensive agricultural runoff. Such evidence of anomalous reproductive physiology and development, termed endocrine disruption, may be symptomatic of serious reductions in reproductive competence and ultimately promote population declines.
Such population declines are occurring in smallmouth bass within the Potomac and Shenandoah River systems and are coincident with high prevalences of TO suggesting a possible link to contaminants entering these systems. One emerging source of contaminants comes from the rapidly growing regional Virginia, West Virginia, and Western Maryland poultry industry which allows runoff of poultry litter-associated contaminants into receiving water following crop and pasture-land application. Similarly, the Eastern Shore of Maryland, Delaware, and Virginia has a substantial and long-established poultry industry producing approximately 700 million kilograms of poultry litter annually, most of which is land applied as fertilizer. Despite the abundance of poultry litter in the region and substantial increases in land application over recent decades, no comprehensive analysis of the influence of poultry litter on resident fish has been undertaken. Given the ecological and economic importance of smallmouth and largemouth bass as keystone predators within regional aquatic food webs, any effects poultry litter might have on bass reproduction are important to residents of Maryland.