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The survival of 1,729 freshwater mussels (15 species) was monitored in ponds at study sites in Critz, Blacksburg and Marion, Virginia. Mussels were held within plastic and metal screen cages fastened to PVC float collars. Survival in the pond at Critz was 73% overall, with significant differences in survival among species after 26 months of captivity. Cyclonaias tub~X_~lJ.t~J_~ and three E11Jptt9 spp. exhibited the highest survivals (x=83%), whereas survival of Pleurobema cordatum and Lampsilis ovata was significantly lower, with 54% and 14%, respectively. Survival of five mussel species in a pond at Blacksburg was high (x=79%) after 7 months, but a nearly complete die-off of captive mussels occurred during hot weather in July, 1994. Survival of six mussel species at the Marion state Fish Hatchery was low for both the sleeve and unrestricted holding methods, 35% and 8%, respectively, after 14 months. It is suspected that excessive accumulation of particulates from pelleted feed contributed to the low survival observed at this site. Survival of four mussel species at Hoge's Pond in Blacksburg was 98% after 6 month. / Master of Science

Electrophoretic variation at twenty gene loci, patterns of behavioral thermoregulation, and genotype-specific malate dehydrogenase kinetics were investigated among populations of the red shiner, Notropis lutrensis, and the blacktail shiner, N. venustus, collected from thermally altered and thermally unaltered portions of their ranges. Genic variation was found to be high among red shiners and low among blacktail shiners. The behavioral response of the blacktail shiner to temperature was fixed among the populations sampled, whereas the response of the red shiner was mutable. Finally, blacktail shiners have incorporated into their genome an Mdh-B allele which functions well at low temperatures; red shiners, displaying high levels of Mdh-B polymorphism, maintain a more complex set of allozymes which function well over a wide range of environmental temperatures. These data are consistent with reported ecotypic distributions of the species in Texas waters; i.e., blacktail shiners occur in cool, thermally static habitats, and red shiners are tolerant of wide temperature ranges.