Abstract

Nonnative fishes have the ability to adapt to environmental conditions in the invaded ecosystem and utilize resources that may have been absent in their native ecosystem. Belonesox belizanus and Cichlasoma urophthalmus are both nonnative fishes in Florida. Ecomorphological studies conclude that C. urophthalmus is a trophic generalist while B. belizanus is a trophic specialist. The current Florida distribution of these species indicates that C. urophthalmus spreads northerly into the colder regions of Florida at a faster rate than B. belizanus. Is it conceivable that this variation in rate of spread is due to differences in temperature response between these ecomorphologically distinct nonnative fishes? This study was designed to test the hypothesis that the prey-capture kinematics and behavior differ between C. urophthalmus and B. belizanus at a given temperature and across temperatures. Two-Way Repeated Measures Multivariate Analysis of Covariance (MANCOVAR) revealed that (1) at a given temperature, excursion and timing variables differed between species and (2) the kinematics of prey-capture did not vary across temperatures in both species. This interspecific comparison suggests that both species have the same temperature tolerance and that any difference in their rate of spread across Florida may be driven by factors other than species-specific physiological tolerance to temperature.

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