A. J. Sonski

Two bluegill subspecies (common bluegill Lepomis macrochirus macrochirus and coppernose bluegill L. m. purpurescens) were subjected to cold tolerance tests in the laboratory. Juvenile and adult bluegills were exposed to water temperature decreases of 1°C/hour from acclimation temperatures of 20° and 30° C until loss of equilibrium. Response temperatures of both subspecies were similar; temperatures at which 50% oftest fish lost equilibrium were usually <1.0° C lower for common bluegill and overlapping occurred in fiducial limits. Bluegill acclimated to 20° C lost equilibrium at 0.6...

Laboratory bioassays were conducted to estimate lower dissolved solids and temperature thresholds of red drum (Sciaenops ocellatus) fingerlings. Tolerance to low total dissolved solids (TDS) was measured by subjecting fingerlings to various test concentrations for 240 hours at 21° ± 1°C. Higher mortality in fresh water than in diluted sea water with similar TDS suggested that concentration of individual ions may be more important than TDS to survival of red drum in fresh water. Survival in solutions of increasing sodium chloride concentrations, but constant TDS, increased and was greater...