DO ROCK BASS (AMBLOPLITES-RUPESTRIS) INDUCE MICROHABITAT SHIFTS IN MOTTLED SCULPIN (COTTUS-BAIRDI)

In Coweeta Creek, North Carolina, mottled sculpin (Cottus bairdi) co-o ccurred seasonally with a potential predator, rock bass (Ambloplites r upestris). We conducted experiments to determine whether rock bass aff ected microhabitat use by sculpin in an artificial stream. The general behavior and microhabitat use of both species in the artificial strea m resembled those observed in Coweeta Creek. When all microhabitat obs ervations were pooled, there was little evidence of predator-induced s hifts by sculpin. However, at night in trials without predators, sculp in generally occurred farther from shelter, over greater amounts of gr avel and lower quantities of erosional substrata. When we added predat ors, however, this response was obviated. Nonetheless, the lack of str ong responses by sculpin to rock bass, coupled with their co-occurrenc e only during seasons of low metabolic activity, lead us to suspect th at rock bass do not produce strong shifts in microhabitat use by most sculpin in the Coweeta drainage.