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EXTRAPOLATING ACUTE MORTALITY OF AMPELISCA ABDITA TO POPULATION RISK USING A POPULATION MODEL AND MONITORING DATA
Citation:
KuhnHines, A, W R. Munns Jr., J A. Kiddon, AND T R. Gleason. EXTRAPOLATING ACUTE MORTALITY OF AMPELISCA ABDITA TO POPULATION RISK USING A POPULATION MODEL AND MONITORING DATA. Presented at The Society of Environmental Toxicology & Chemistry Annual Meeting, Nashville, TN, November 12-16, 2000.
Description:
Ten-day acute mortality of the benthic amphipod, Ampelisca abdita, is used in a number of regulatory, research, and monitoring programs to evaluate chemical contamination of marine sediments. Although this endpoint has proven to be valuable for characterizing the relative toxicities of sediments, the ecological significance of acute mortality as an indicator of risks to populations of benthic species has not yet been established. In this study population modeling along with empirical extrapolation were used to describe the relationship between acute mortality and population-level response of A. abdita. The research involved the performance of a standard I0-d sediment toxicity bioassay and a 70-d chronic population (including reproduction) bioassay exposing A. abdita to sediments spiked with a range of concentrations of the divalent metal cadmium (normalized to acid volatile sulfide). These data provided age-specific schedules of survival and fecundity that were used to parameterize an age-classified projection matrix model for A. abdita. Treatment-wise population growth rate estimates, obtained using the demographic information collected during the 70-d assay, and measured exposure data were used to develop exposure- response models. Population growth rates ( ) were regressed against the acutel0-d mortality to establish the relationship between the two allowing direct extrapolation between acute mortality and population-level endpoints based upon empirical results. These relationships were used to establish a range of ecologically acceptable acute mortality for A. abdita. An evaluation of this method for extrapolating risk to populations from acute mortality was then performed by analyzing field survey data sets (U.S. EPA's Environmental Monitoring and Assessment Program (EMAP) and Regional-EMAP (REMAP)) that contain synoptically collected exposure information (chemistry, grain size, etc.), estimates of benthic species abundances, and acute sediment toxicity results obtained using A. abdita. The results of this analysis help to bound the uses of acute sediment bioassays as predictors of risks to populations.