Invasion
Invasion Description
1st Record: Beaufort area/NC/Newport River (Wells 1961; Hopkins 1970)
Geographic Extent
NC/South Creek, Pamlico River (Tenore 1968; Foltz et al. 1995); Beaufort area/NC/Newport River (1955, Wells 1961; Hopkins and Andrews 1970); SC/estuaries, oligohaline, uncommon (Shoemaker et al. 1978); GA/Altamaha River (1958, Hopkins and Andrews 1970); 5 mi. South of Jacksonville/FL/St. Johns River (Museum of Comparative Zoology 2009, cryptogenic); 1 mi. ESE, Osceola/FL/St. Johns River (Museum of Comparative Zoology 2009, cryptogenic); 21 mi W. of St. Augustine, vicinity of State Rd., Shandy bridge/FL/St. John River (1965, Museum of Comparative Zoology 2009, cryptogenic)
Vectors
| Level | Vector |
|---|---|
| Alternate | Oyster Accidental |
| Alternate | Ballast Water |
| Alternate | Canal |
Regional Impacts
| Ecological Impact | Habitat Change | |
| Habitat Change - Survivorship of the native bivalves Mya arenaria and Macoma balthica was increased in the presence of R. cuneata, but empty shells had similar effects (or greater in M. arenaria) as live clams, indicating that the shells of R. cuneata were providing a physical refuge (Skilleter 1994). The seagrass Ruppia maritima (Widgeon Grass), when present, apparently removed this protective effect, perhaps by interfering with burrowing, or by attracting predators (Skilleter 1994). | ||
| Ecological Impact | Competition | |
| Competition - Effects of R. cuneata on the native clams Mya arenaria (Softshell Clams) and Macoma balthica (Baltic Clams) are complex and subtle. Competition for food is likely; since suspension feeders can deplete plankton in the immediate vicinity. Macoma balthica, in the presence of R. cuneata, switched to deposit feeding, resulting in increased rates of partial predation (siphons nipped) (Skilleter and Peterson 1994). This results in energetic costs of regeneration and could slow growth. These effects are apparently partly offset by structural refuges provided by R. cuneata (Skilleter 1994). | ||