Interactions Between a Native Predator (Epinephelus morio) and Invasive Lionfish (Pterois volitans/miles) in Florida Bay

The effects of native predators on invasive Indo-Pacific Lionfish (Pterois volitans/miles) are still largely unknown. In addition to population control via direct consumption, native predators may alter the strength of Lionfish effects on reef fish populations via behaviorally mediated interactions. Lionfish are known to co-occur with Red Grouper (Epinephelus morio) in karst solution-holes which are excavated and maintained by the grouper. In 2013 I conducted an experiment to study the effects of Lionfish-Red Grouper interactions on the abundance of juvenile reef fishes (JRFs) that recruit to solution holes where either Lionfish were present, Red Grouper were present, both species co-occurred, or both were absent. JRF species abundances were recorded weekly by SCUBA divers. After six weeks, solution holes with only Lionfish present had significantly fewer JRF recruits compared to holes with only Red Grouper present (7.75 ± 8.43 vs. 105 ± 33.0; z = -3.49, p = 0.00285). At solution holes where Red Grouper and Lionfish co-occurred, the abundance and species richness of JRFs did not differ from holes where neither predator was present, suggesting that Red Grouper enhanced JRF presence in the absence of Lionfish and ameliorated the negative effects of piscivory by Lionfish via behaviorally mediated indirect interactions.