The Effects of Seasonal Changes and Turbidity on Swimming Performance in White Crappie Pomoxis Annularis and Black Crappie Pomoxis Nigromaculatus.

Factors that affect swimming performance in fish can also affect fitness. I tested the effects of time of day, season and turbidity on swimming performance in black crappie Pomoxis nigromaculatus and white crappie Pomoxis annularis. These closely related fish co-occur and their relative abundance is thought to be governed by the levels of turbidity in the form of suspended sediments. Black crappie predominate in clear bodies of water and exhibited significantly greater critical swimming speeds in clear water than did white crappie during spring days and winter nights. A significant reduction in critical swimming speed was observed in black crappie as turbidity increased. White crappie predominate in turbid bodies of water and exhibited no significant reduction in critical swimming speed in relation to increasing turbidity. Both species displayed a significant increase in oxygen consumption in response to elevated turbidity. There were no differences in oxygen consumption rates between the two species within any of the four seasons or at the three levels of turbidity tested