State Water Resources Research Institute Grant

Polychlorinated biphenyls (PCBs) are ubiquitous aquatic pollutants with significant toxic effects in both humans and fish, including altered reproduction, immunosuppression, carcinogenesis, and neurotoxicity. Significant levels of environmental PCBs in Kentucky have led to the posting of fish advisories in several Kentucky waterways (Kentucky Division of Water). The focus of the present study is the Town Branch-Mud River (TB/MR) system in Kentucky, a PCB-contaminated site currently under remediation. This proposal addresses several needs identified by the Water Science and Technology Board (Board, 2000), including the need to understand the impact of contaminants on higher organisms, to monitor the time course of recovery following contamination, and to evaluate the effectiveness of management efforts to improve water quality. The problem: Water quality in Kentucky is evaluated based on contaminant concentrations in water, sediment or biota, and/or on biological indices of species diversity. Contaminant concentrations alone provide no information on organism response, and diversity indices do not distinguish between response to contaminants, habitat disturbance, or natural stressors. For example, there is no information on whether exposure to PCBs in the TB/MR system is producing sublethal effects in fish populations in that system, and/or whether present remediation efforts are reducing those effects. The enzyme, CYPIA, is strongly and rapidly induced in animals exposed to toxic organic pollutants, including PCBs. We hypothesize thatCYPIA levels in TB/MR resident fish reflect organic contaminant levels at their site. Our objectives are 1) to determine ifCYPIA levels in resident fish in the TB/MR system reflect expected habitat contamination level, and 2) to use CYPIA levels in caged fish to evaluate the effectiveness ofbioremediation efforts in the TB/MR system. Approach: To evaluate the response of resident fish species, we will measure hepatic CYPIA expression in fish collected from reference, remediated and unremediated sites in the TB/MR waterway. Species will be selected based on known sensitivity to CYPIA inducers and on our ability to collect statistically-sufficient numbers of individuals at each site to distinguish site differences in CYPIA response. Resident fish may not adequately reflect conditions at the site of capture as some species may move between remediated and unremediated areas, while others may have developed resistance to PCB induotion of CYP 1A. For these reasons, we will also cage reference fish at each study site to provide a second site~to-site evaluation of the effectiveness of bioremediation efforts in the TB/MR system. Significance: The current clean-up efforts in the TB/MR provide an unparalleled opportunity to evaluate the effectiveness of site remediation using local populations. The results ofthese studies will provide insight into the response of resident and caged fish to present conditions in the TB/MR, and indicate the effectiveness ofbioremediation efforts currently. underway in this system. The extraordinary sensitivity, rapidity of response, and relative ease of measurement ofCYPlA expression in fish makes CYPIA a promising tool for monitoring the biological effectiveness of site remediation and the time course of habitat recovery. As a monitoring tool, elevated CYPIA activity at remediated sites could indicate insufficient remediation, reintroduction of the contaminant, or introduction of new contaminants to the site, and serve as one basis for management decisions on the need for reevaluation of site contamination by more expensive methods. Additionally, elevated CYPIA levels can be used to identify hot spots, or newly contaminated sites, and serve as an early warning system to alert managers to the need for remediation elsewhere in the system.