Effects of turbidity, velocity and competition on foraging behavior of two southeastern minnows
Hazelton, Peter Donald
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Increased stream turbidity and biological invasions are two important challenges affecting native fish assemblages in the southeast United States. I examined the effects of turbidity and velocity on competition for food and foraging positions in a native (rosyside dace, Clinostomus funduloides) – introduced (yellowfin shiner, Notropis lutipinnis) interaction. Previous research in our lab has shown that elevated turbidity has a negative effect on the reactive distance and foraging success of C. funduloides, and that N. lutipinnis is a more successful competitor at low current velocities in non-turbid conditions. I compared foraging success, reactive distance, movement, holding position and aggression rates among intra and interspecific groups of competitors at two densities (2 & 4 fish), three turbidity levels (10, 20, & 30 NTU), 12 & 20 cm/sec velocity, and spring temperatures (10-12°C). I found that both environmental and social variables are needed to best predict changes in foraging behavior of both species.