The Nonindigenous Asian Clam, Corbicula fluminea, in New Hampshire

The nonindigenous Corbicula fluminea (Asian Clam) continues to spread northward into cooler waters of the northeastern US. This range extension has been previously attributed to thermal discharges acting as refugia. We conducted an extensive survey for the Asian Clam in New Hampshire waters lacking artificial thermal influence. Using scuba, divers searched for evidence of the Asian Clam at 67 south-central and southeastern New Hampshire locations. We found 6 new locations with Asian Clams for a total of 13 sites in New Hampshire, 12 without thermal discharge. Sites with Asian Clams were limited to south-central and southeastern New Hampshire. Continued expansion of the Asian Clam into northern cold waters suggests that thermal refugia are not necessary and that the Asian Clam populations may have obtained adaptations via natural selection to withstand cold winter water temperatures.