Predation of the non-native Asian shore crab Hemigrapsus sanguineus by a native fish species, the cunner (Tautogolabrus adspersus)

Abstract

Predation of non-native species by native predators can impact the success of an invasion. Recently, the Asian shore crab, Hemigrapsus sanguineus, successfully invaded the northeastern coastline of the United States, reaching densities greater than 100crabs·m−2 in rocky intertidal areas. The goal of this study was to determine if a specialist fish predator of invertebrates, the cunner, Tautogolabrus adspersus, consumes the juvenile stage of H. sanguineus. In laboratory prey choice experiments, T. adspersus (10.2–22.1cm total length) consumed greater numbers of native mud crabs (family Panopeidae, 3.0–9.0mm carapace width) than H. sanguineus of similar sizes. T. adspersus also consumed more of the native blue mussel, Mytilus edulis, when paired with similar-sized H. sanguineus. Gut content analysis of 60 T. adspersus captured from intertidal zones with high populations of H. sanguineus in southeastern Massachusetts revealed low consumption of the invasive species; only 5 of 60 guts contained Asian shore crabs. Frequent prey items found in cunner guts included panopeid crabs, small snails, barnacles, and branching and encrusting bryozoans. Our results suggest that, as long as native prey species are present for consumption, T. adspersus will not exert high predation pressure on H. sanguineus.