Temperature regime drives differential predatory performance in Largemouth Bass and Florida Bass

Abstract

Predation shapes community structures via direct and indirect mechanisms and it is an ecological imperative that predatory impacts are predicted. In this study, we used comparative functional responses (FRs) to compare resource utilisation (i.e. per capita effects) between young-of-year Largemouth Bass and Florida Bass across different temperatures treatments (18, 24 and 30 °C). Culex mosquito larvae were used as prey during the experiments. Across all temperature treatments, Type II FRs were observed, which could cause population-destabilising pressures towards native prey communities due to high predation rates at low prey densities. Attack rates did not differ significantly between the fish species at either temperature. Handling times of Largemouth Bass increased significantly with temperature, whilst the converse was true for Florida Bass. Largemouth Bass were found to have higher maximum feeding rates at the low temperature (18 °C), driven by significantly shorter handling times compared to Florida Bass. At the intermediate temperature (24 °C), handling times and thus maximum feeding rates did not differ significantly between the two species. At high temperature (30 °C) Florida Bass exhibited a significantly higher maximum feeding rate and shorter handling time than Largemouth Bass. These results suggest that temperature drives differential ecological impacts, with Florida Bass exerting higher impact than Largemouth Bass on prey at high temperatures and Largemouth Bass having higher impacts than Florida Bass at lower temperatures.