Behavioral Response of Small Everglades Fish to Hydrological Variation, Predator Cues and Parasites

Behavioral Response of Small Everglades Fish to Hydrological Variation, Predator Cues and Parasites

Small fish are important to the Everglades ecosystem as primary and secondary consumers and as a food source for higher trophic levels. In short-hydroperiod wetlands, these fish must migrate to refuge areas or risk stranding, and have been observed to rapidly recolonize during the wet season. The goals of this study are to understand what influences annual migrations to and from short-hydroperiod wetlands. We aim to link individual variation in behavior to population-level movement. We specifically tested whether the willingness of fish to explore and move through unknown environments varied among species, with hydrological season, wetland hydroperiod, or parasite load). We tested the hypothesis that waterborne cues might influence risk aversion and likelihood of entering unknown areas. We used a factorial experimental design to measure effects of visual predator cues (using a bird model), chemical cues from bird feces, or food motivation on the behavior of eastern mosquitofish. Fish were filmed exploring an artificial habitat, and we examined data like the time spent hiding, total distance traveled, variation in speed and other movement variables. We found that behavior varied significantly among species, with eastern mosquitofish (Gambusia holbrooki) the most likely to explore and golden topminnow (Fundulus chrysotus) the least so. Most fish were parasitized, some with parasites from taxa known to modify host behavior. To date, small sample size limits our ability to draw conclusions from this experiment, but it seems likely that these factors influence fish migration in nature.