Idiosyncratic anti-predator responses of two desert fishes to invertebrate predation risk

Authors: Bridger Scraper, Sekhar M.A., Shawn Goodchild, Craig Stockwell, Brian Wisenden

Year: 2022

Abstract

The evolutionary naiveté hypothesis has been invoked to explain the vulnerability of isolated desert fishes to non-native predators, but until recently the behavioral mechanisms have not been explored. Recent work showed that Moapa White River springfish, Crenichthys baileyi moapae responded to conspecific chemical alarm cues, whereas Pahrump poolfish, Empetrichthys latos did not respond to alarm cues. These differential responses call for a better understanding of anti-predator behavior toward non-native predators as well as native predators. Nymphs of various dragonflies have been reported to prey on the larvae of aquatic vertebrates, but little work has explored dragonfly predation on the larvae of desert fishes. Here, we evaluate poolfish and springfish responses to a native odonate predator, the green darner, Anax junius, because it co-occurs with various desert fishes. We conducted mesocosm experiments and time to capture trials to explore population-level and individual-level responses to nymphs of the green darner. In experimental mesocosms, dragonfly nymphs reduced the number of poolfish larvae produced, whereas dragonfly nymphs had no negative effect on the number of springfish larvae produced. Staged time-to-capture interactions between dragonfly larvae and juvenile fish show that springfish are highly vulnerable to dragonfly predators. Time to capture for poolfish will also be reported. Finally, we will present data on larval behavioral responses to alarm cue for both springfish and poolfish that were hatched either in the presence or absence of dragonfly nymphs. These findings suggest that dragonflies may impact desert fish species, but individual-level and population-level responses do not directly correspond. These studies will provide insights on how evolutionary history with native predators may facilitate or constrain anti-predator responses to non-native predators.