Using bivalve mollusks as sensors in an early warning, automated biosensing system for water resource protection

摘要

"No instrument has yet been devised that can measure toxicity! Chemical concentrations can be measured with an instrument but only living material can be used to measure toxicity" (Cairns & Mount 1990). Because a large number of substances can contribute to problems in a water resource, monitoring for numerous substances that may produce a toxic risk using traditional physical and chemical analytical methods is not practical. Similarly, the slow turnaround time inherent in performing traditional toxicity assays becomes prohibitive if one wishes to protect sensitive aquatic organisms and potable water supplies from toxicant contamination. One approach to reducing time delays inherent in traditional water quality monitoring programs would be to employ an automated biosensing system, one that uses both physical-chemical and biological methods providing continuous, real-time surveillance of toxic risk to aquatic organisms. Aquatic animals induce bioelectrical signals from myoneural functions that can be detected and recorded as periodic analog signals representing specific physiological activities, i.e. EKG signals in bivalve mollusks. Direct exposure of the animal's respiratory surfaces to water makes them particularly susceptible to toxic stress, which produces distinct signal changes. Using appropriate sensors and instrumentation, bioelectric action potential signals can be monitored and utilized to access the contaminant-induced stress in monitored bivalves. Real-time bioelectric responses can be processed and used as biological end-points reflecting the quality of a water resource, and as a component of an early warning system to potential toxic risk (Morgan et al. 1987, 1988, 1989, Meiyappan et al. 1996).