Examining the Effectiveness of Consumer Diet Sampling as a Nonnative Detection Tool in a Subtropical Estuary

In aquatic systems, developing effective detection and monitoring methods is of the utmost importance in nonnative species management. One complement to monitoring that may increase nonnative capture probabilities is to sample the diets of consumers. However, no study has yet tested whether consumer diet sampling can be an effective tool in nonnative fish detection and monitoring. Recently, an extreme cold front swept through South Florida, severely impacting nonnative fishes and resetting invasion trajectories throughout Everglades habitats. Using the loss of nonnatives from the cold front as a natural experiment, we tested whether we would first find tropical nonnative fishes impacted by the 2010 cold front with consumer diet sampling or by electrofishing. We sampled consumer diets and electrofished monthly from 2010 to 2013 in the oligohaline reaches of an Everglades estuary. Three years after the cold front, we detected six nonnative fish species. All six were found in consumer diets, while only three were found via electrofishing. Two of the three nonnatives found in both electrofishing and diet samples were detected approximately 30 d from each other, while one was detected much sooner with electrofishing. Our findings show that consumer diet sampling can be an effective complement to conventional nonnative detection and monitoring efforts. Received July 7, 2013; accepted October 24, 2013