Habitat dominance of a nonindigenous tropical bivalve, Perna viridis (Linnaeus, 1758), in a subtropical estuary in the Gulf of Mexico

Abstract

The green mussel Perna viridis (Mytilidae) is a recent invader in the Atlantic basin including the Caribbean region and southeastern USA. In this study we examined the relative abundance of P. viridis across habitats in Tampa Bay, Florida, and density patterns at specific sample sites. Pilings, piers and floating objects were favourable habitats for P. viridis, while mangroves, flats and seawalls were not, although these were occasionally inhabited by P. viridis. Density and size-class distribution of P. viridis were estimated from approximately monthly samples collected between April 2002 and March 2003. Density of P. viridis varied significantly with sample date, reaching a maximum of 4,000 m -2 in September. Perna viridis exhibited the ability to dominate some habitats within the Tampa Bay ecosystem and the potential to compete for space with native species such as the eastern oyster, Crassostrea virginica, but the impacts were neither consistent nor widespread. Crassostrea virginica appears to have some refuges from P. viridis, while a small native mussel, Brachidontes cf. exustus, co-occurs with P. viridis in most sites; its density appears to be independent of P. viridis density. © 2011 The Author.