Abstract
In the Columbia River basin, mercury is identified as one of the four primary contaminants of concern that necessitates continuous environmental reconnaissance. Mercury’s propensity to accumulate into organic rich media calls for the use of sentinel organisms in order to monitor and geospatially analyze its distribution in the environment, however, such use depends upon the standardization of concentrations within the animal. The studies presented in this thesis sought to investigate how intrinsic factors associated with a candidate sentinel organism, the crayfish, influence the total mercury concentration (THg) in its tissues. The first study discusses how THg in the adductor muscle of male and female signal crayfish (Pacifastacus leniusculus) allometrically scales with the clawless body mass (CBM) of the individual from different locations of variable mercury contamination. In this study, the results are interpreted in the context of how size and sex influence THg in the signal crayfish, and whether the influence of these intrinsic factors are consistent across geographies and levels of contamination. The second experiment assess how tissue morphometrics influences tissue THg in male and female virile crayfish (Faxonius virilis). The results from this study suggest that hepatopancreas and adductor muscle THg in male virile crayfish allometrically scale with the CBM of the individual, and that detectable levels of THg in the gill tissue is significantly associated with THg in size-adjusted hepatopancreas, but not in the adductor muscle. Relative to females, tissue atrophy associated with reproductive stage in female virile crayfish does not bioamplify THg. While this atrophy indicates a loss in mercury mass in tissues undergoing wholesale changes in mass, mercury is not redistributed into reproductive tissues of either reproductive stage for female virile crayfish. The final section focuses on the potential for these two species to be used in mercury reconnaissance efforts in the Columbia River Basin based upon a robust understanding of how intrinsic factors influence tissue THg and their utility in community-based participatory methods.