Influence of Physico-Chemical Factors on Habitat Selection by Red Shiners, Notropis lutrensis (Pisces: Cyprinidae)

Abstract

Field studies were combined with single and multifactor laboratory preference tests to determine the relative influence of temperature, oxygen, pH, total dissolved solids and turbidity on red shiner habitat selection. Distribution of the species at a field site was also quantified with respect to current speed, water depth, shelter, shade and substrate type. Temperature, current speed and water depth had greatest impact on habitat selection of the species during the study. Gradients of total dissolved solids or pH can markedly influence habitat selection by red shiners; dissolved oxygen, turbidity, shelter, shade and substrate are apparently of lesser importance. Red shiners avoided temperature extremes in winter and summer, and consistently selected water deeper than 20 cm with negligible flow. They avoided highly alkaline conditions in the field, and generally selected pH of 7.1-7.4 in the laboratory. Response to total dissolved solids was strong in the laboratory, but the shiners did not respond to this factor in the field when its range was less than 500 ppm. The shiners avoided unsheltered locations and clean, unstable sand substrate. No consistent response to turbidity or shade was noted.