Assessing Potential Crab Predators of the Invasive Gonionemus vertens

Invasive species are a global problem and one such species is Gonionemus vertens, otherwise known as the Clinging Jellyfish. Gonionemus vertens is a hydrozoan that has invaded waters globally and it is a growing problem in New Jersey, USA. Gonionemus vertens live in shallow water with seagrass or algae that they can cling to. Many invasive species become successful because competition is limited and/or predation is reduced. In New Jersey, G. vertens has been shown to have at least one predator capable of actively consuming them, the scyphozoan Chrysaora chesapeakei. In other regions of the USA, spider crabs have been shown to be potentially an important predator. Previous experiments have shown that the spider crabs native to Barnegat Bay, Libinia sp., have the ability to eat G. vertens. Experiments were conducted to determine whether other abundant crab species could also serve as potential predators on these invaders. The crabs chosen included small Xanthid crabs, green crabs (Carcinus maenus), and blue crabs (Callinectes sapidus). Xanthid and green crabs showed little interest in G. vertens as food, but blue crabs not only showed little interest, they actually avoided and ran away from then when they encountered them. Subsequent choice experiments with spider crabs using G. vertens and alternate prey (blue mussels) indicated that the spider crabs preferred the higher quality mussels but would passively consume G. vertens when they encountered them. Continuing research is needed to understand the trophic interactions of G. vertens as both prey and predator in this invaded habitat.