Invasion
Invasion Description
The Atlantic Coast of this region, from Cape Canaveral to Cape Sable, is in a hybrid zone, where M. mercenaria and M. campechensis occasionally interbreed (O'Foighil et al. 1996; Arnold et al. 2009).
Geographic Extent
FL/Mosquito Lagoon (2002, Arnold et al. 2009, native, with some M. campechensis hybrids); Sebastian/FL/Indian River Lagoon (2003, native, with some M. campechensis hybrids); FL/St. Lucie Inlet, Seminole Shoals, Sand Flats (1982, USNM 841367, US National Museum of Natural History 2012, native); Cape Romano/FL/Gulf of Mexico (2002, Arnold et al. 2005, only 2 specimens found, aquaculture started after sampling, in 2005); Pine Island/FL/Pine Island Sound (1997, Arnold et al. 2009, aquaculture started, M. mercenaria and hybrids present, 2003); FL/Charlotte Harbor (1994, Arnold et al. 2009, aquaculture started, 2003, hybrids present); FL/Sarasota Bay (1960, Arnold et al. 2009, scientific releases; 2003, some hybrids found); FL/Tampa Bay (1960, Arnold et al. 2009, adults and hybrids found, no hisory of aquaculture, M. mercenaria abundant on oyster bed, rare on sand flat); Cedar Key/FL/Gulf of Mexico (1993, open aquaculture lease site, sampled 2003); FL/Alligator Harbor (1958, Arnold et al. 2012, in 2003, M. mercenaria and hybrids predominated)
Vectors
| Level | Vector |
|---|---|
| Alternate | Scientific Escape |
| Alternate | Fisheries Accidental (not Oyster) |
Regional Impacts
| Ecological Impact | Hybridization | |
| Hybrids between Mercenaria mercenaria and M. campechiensis comprised 13-30% of the clams collected. Hybrids were present even at sites where purebred M. mercenaria were absent, suggesting that introgression was primarily affecting the genotypes of N. campechiensis populations. However, this introgression may be offset by the increased prevalence of neoplasia in hybrids (Arnold et al. 2009). | ||
| Economic Impact | Fisheries | |
| Mercenaria mercenaria is now being reared in aquaculture operations in many locations on the Gulf Coast of Florida. This clam is considered superior to the native M. campechiensis due to its longer shelf life. In these operations, hatchery-reared seed clams are planted in intertidal sands and grown in mesh bags to keep out predators (Arnold et al. 2009). | ||