An experimental simulation of an exotic aquatic macrophyte invasion and its influence on foraging behavior of bluegill

We investigated the hypothesis that a shift from a native aquatic plant bed to an exotic invasive Hydrilla verticillata (hydrilla) plant bed would alter spatial complexity and light transmittance and therefore alter Lepomis macrochirus (bluegill) foraging success. Experimental treatments included: (i) intermediate densities of native-mixed plants and (ii) 50% native - 50% hydrilla, (iii) hydrilla, (iv) high density of hydrilla, and (v) no plants. Spatial complexity and light transmittance were influenced by increasing the homogeneity of hydrilla in vegetated aquatic habitat. In addition, bluegill foraging efficiency was affected negatively by increasing spatial complexity of a hydrilla dominated habitat. As a result bluegill searched faster, exhibited 60% more mean foraging bouts, and recognized 38% more food items in a native diverse habitat versus a hydrilla dominated habitat.