Invasion
Invasion Description
1st Record: Normandy/France/English Channel (1973-1974, Goulletquer et al. 2002)
Geographic Extent
Essex/England/English Channel (1980, Utting and Spencer 1992); Conwy/Wales/Menai Strait (1980, Utting and Spence 1992); Portland/England/The Fleet (& Portland Harbour, Humphreys et al. 2015, common in harbor); Dorset/England/Poole Harbour, English Channel (1988, Jensen et al. 2004; Herbert et al. 2012; Humphreys et al. 2015, present, rare); Southampton/England/Southampton Water (Humphreys et al. 2015, common); Portsmouth/England Portsmouth Harbour (Humphreys et al. 2015, common); England/River Blackwater (Humphreys et al. 2015, common); Normandy/France/English Channel (1973-1974, Goulletquer et al. 2002); England/Thames estuary (1988, Humphreys et al. 2015, common)
Vectors
| Level | Vector |
|---|---|
| Probable | Fisheries Intentional |
Regional Impacts
| Ecological Impact | Habitat Change | |
| In Poole Harbour, England, R. philippinarum, was the second most important species contributing to bioturbation of sediments (Queiros et al. 2011). | ||
| Economic Impact | Fisheries | |
| In French waters, hatchery stocks were established in 1972, and a commercial fishery was established by 1984. By 1992, it was sustained by natural breeding, although adversely affected by Vibrio infections. The harvested clams were mostly exported to Spain (Flaasch and LeBorgne 1992). A winter fishery has developed in Poole Harbour, England, for R. philippinarum. The fishery depresses clam abundance, but appears to be sustainable (Humphreys et al. 2007). | ||
| Ecological Impact | Food/Prey | |
| In Poole Harbour, England, R. philippinarum may be an important food for Eurasian Oystercatchers (Haematopus ostralegus), a bird considered to be an indicator of ecosystem health (Jensen et al. 2004). Modeling suggests that the high density of R. philippinarum has reduced winter mortality of the Eurasian Oystercatcher at Poole Harbour. The spread of this clam is considered a potential benefit to European shorebirds (Caldow et al. 2007). Excretion of inorganic carbon and nutrients by R. philippinarum stimulates microbial activity in intertidal sandflats, both when submerged at high tides, and energed at low tides (Mign et al. 2018). However, it is unclear whether these effects are different feom those of natïve bivalves. | ||