Effects of zebra mussel (Dreissena polymorpha) density on the survival and growth of juvenile fathead minnows (Pimephales promelas): Implications for North American river fishes

I used replicated 37.8 1 aquaria in a factorial design (four densities of zebra mussel, Dreissena polymorpha; two hydrologic regimes) to determine if the survival or growth of juvenile fathead minnows (Pimephales promelas) was affected by the density of zebra mussel or by the retention time of the test system. None of the fathead minnows died during the 30-d experiment. However, growth of fathead minnows was lower (P<0.05) at the highest (3000 m⁻²) than at the lowest density of mussels (0 m⁻²). Fish growth was not affected by water retention time or the interaction of water retention time and mussel density (P>0.05). These laboratory results suggest that juvenile fish survival will not be affected by low to moderate densities of mussels (0–3000 m⁻²) but fish growth might be adversely affected at moderate densities of mussels (e.g., 3000 m⁻²).