Quantifying Effects Of Temperature On Respiration Of Selected Mussel Host Fish In The Mobile River Basin

Many freshwater mussels require specific host fish species to complete the parasitic portion of their complex life cycle.  Despite this we know little about the abiotic requirements of many host fishes, likely because many are non-game species that have received relatively little research attention.  Here we used respirometry to quantify the influence of temperature and dissolved oxygen as potential stressors on host fishes.  We quantified routine metabolic rates and critical oxygen tension for 4 fish species from the Mobile River Basin (Percina palmaris, Etheostoma jordani, Cyprinella venusta, Micropterus coosae) at three temperatures.  Combining intermittent flow with static respirometry allowed us to measure oxygen consumption and estimate critical oxygen tensions.  For all species, respiration increased with temperature as expected; the increase was largest for M. coosae and smallest for C. venusta. Oxygen consumption remained constant as dissolved oxygen decreased until a critical threshold was reached, below which respiration decreased sharply for all species except E. jordani (which had a gradual non-linear decline).  Our results will allow us to derive functional relationships of respiration relative to body size, temperature, and dissolved oxygen for these species, with the goal of determining water quality standards for tailrace areas below hydropower facilities.