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(IP23) Sensitivity of a time-relevant, bivalve biomonitoring system to copper and zinc.
Allen, H. Joel*,1, Turner, Phillip1, Waller, William1, 1 University of North Texas, Denton, TX
ABSTRACT- Biologically based, time relevant measures of water quality are of interest to toxicologists and environmental managers because of their utility in continuous screening of water quality. Current technology has enabled the monitoring and analysis of behavioral and physiological endpoints in a variety of species in both laboratory and field applications. Results presented here were obtained using a bivalve biomonitoring system developed for use in a watershed or process context. The operational premise of the bivalve biomonitoring system is that bivalves close their valves when adverse environmental conditions are detected. Sensitivity of this bivalve biomonitoring system to copper and zinc was determined under laboratory conditions. The system consisted of 15 Corbicula fluminea, inductive proximity sensors, a laptop PC, and data collection and analysis software. The behavioral endpoint gape was measured at a frequency of once per minute. The metric mean gape was analyzed for coordinated behavioral changes which were considered to be an acute response. Mean gape state was predicted using autoregression. Predicted gape state was compared with the observed gape state to determine the degree of deviation from expected behavior. Organisms were held and exposed in a flow through system with water from a natural source, the University of North Texas Water Research Field Station. Toxicant was introduced on a gradient over a period of one hour and twenty minutes after which, uncontaminated water was reintroduced. As expected, Cu was observed to be relatively more toxic than Zn. The nominal effective concentration for Cu was 192.5g/L. A clear bivalve gape response was not observed with nominal concentrations of Zn as high as 2.5mg/L. However, deviations in behavior were observed at concentrations as low as 500g/L. The concentrations of Cu and Zn eliciting an acute behavioral response were within the range of LC50 values of other organisms used in toxicological screening. Work continues to further characterize the effective concentrations of these and other chemicals.
Key words: time-relevant biomonitor, bivalve, copper, zinc
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