|From USGS paper cited below|
Earlier this month Vicki Blazer of the U.S. Geological Survey published a new paper, “Indicators of Reproductive Edocrine Distruption in Fish in the Chesapeake Bay Watershed.” Dr. Vicki Blazer is a mairine biologist and researcher at the U.S. Geological Survey, USGS. Dr. Blazer received the American Fisheries Society 2010 Publications Award for her article investigating the mortality of fish in the Potomac River basin and is a fish biologist at the West Virginia Science Center studying the impact of contaminants of emerging concern in rivers and streams of the lifecycle and health of fish on the Chesapeake Bay and its tributaries. This paper is a summary of the most recent research (previously published) by the USGS and others on endocrine disruption in fish in the Chesapeake Bay watershed and the implications to our lives.
The Chesapeake Bay watershed feed the Chesapeake Bay, the largest and most productive estuary in the United States. It serves as a nursery ground for the fish and shellfish industry and protects the coast from storm surges and filters pollution. The estuary filters water that is carrying nutrients and contaminants from the surrounding watershed. The nutrients in proper balance bring fertility, but excess nutrient contamination to the Chesapeake Bay has caused degradation in the habitat and impact to fish and other animals. As a result, US EPA has taken control of the situation and has developed a new federally mandated TMDL (total maximum daily load) to try to restore the natural balance in the estuary by controlling nutrients in the local waters. The TMDL addresses pollution from phosphorus, nitrogen and sediment and allocates a pollution budget among the states which will decrease over time. However, according to Dr. Blazer, the fish (and other aquatic organisms) in the Chesapeake Bay watershed are being exposed to a complex mixture of chemicals that may have additive, synergistic or antagonistic effects.
In the Potomac River watershed, largemouth bass show signs of feminization (testicular oocytes and vitellogenin in males) but appear to be less sensitive than smallmouth bass to the effects of estrogenic compounds. The scientists discovered that the smallmouth bass have both a higher incidence of intersex (male fish with eggs) occurrence and a high incidence of skin lesions and large fish kills in the Potomac and James Rivers. Smallmouth bass may be the most sensitive indicator of environmental health in the Chesapeake Bay watershed. The smallmouth bass is a warning that should not be ignored, but the pollution problem they represent are beyond our understanding at this time. More work needs to be done.
Although feminization of male fish has most commonly been associated with exposure to human wastewater-treatment-plant effluent, the prevalence of male smallmouth bass with intersex characteristics is not consistently higher downstream from these point sources than upstream in the areas of the Potomac River watershed that were studied. It is not simply the residue of birth control pills in human waste. However, some additional biomarkers, such as the ratio of gonad weight to body weight and plasma vitellogenin concentrations in female bass, do appear to be adversely affected by the presence of wastewater-treatment plants upstream from the study site, but more is going on.
The sources of the endocrine-disrupting chemicals associated with intersex smallmouth bass appears to be BOTH effluent from wastewater-treatment plants and runoff from agricultural land, animal feeding operations, and urban/suburban land. All impacts of mankind. Other factors, including wastewater-treatment-plant effluent flow, number of animal feeding operations, and number of poultry houses were also associated with an increased intersex severity. Within the Potomac River basin the data showed that the higher the human population density the higher the incidence of intersex in the smallmouth bass. Also, the higher the percentage of agricultural land use density the higher incidence of intersex in smallmouth bass. The data appears to suggest beyond a certain density of agricultural land and/ or human population, the smallmouth bass population is impacted.
The USGS plans to work with the Chesapeake Bay Program to identify the chemicals that are causing the intersex, skin lesions and fish kills. The Chesapeake Bay Program intends to develop toxic contaminant reduction strategies to be added to the Chesapeake Bay TMDL by 2015. The impact on human life and the ecosystem of these and other emerging contaminants is not known, but now is the time to find out the impact from the substance we’ve been allowing to enter the waters of the earth. We need to determine the impact and fate of these micro pollutants before we implement the watershed cleanup plans to make sure we are implementing the right strategies for the health of the entire ecosystem which may include eliminating the use of certain chemicals and other actions.