COMPARATIVE SURVIVORSHIP OF SYMPATRIC NATIVE NORTH-AMERICAN GASTROPODS (ANGUISPIRA, MESODON, PHYSELLA, PLEUROCERA) AND AN INTRODUCED BIVALVE (DREISSENA) EXPOSED TO FREEZING TEMPERATURES
Gl. Paukstis et al., COMPARATIVE SURVIVORSHIP OF SYMPATRIC NATIVE NORTH-AMERICAN GASTROPODS (ANGUISPIRA, MESODON, PHYSELLA, PLEUROCERA) AND AN INTRODUCED BIVALVE (DREISSENA) EXPOSED TO FREEZING TEMPERATURES, The Veliger, 40(1), 1997, pp. 67-70
Seventy-four specimens from four genera of native gastropods were cool
ed from 2.0 degrees C to -3.3 degrees C over a 3 hour period under lab
oratory conditions. The taxa examined included two terrestrial pulmona
tes (Anguispira alternata and Mesodon inflecta), a pulmonate known to
occupy both permanent and ephemeral aquatic habitats (Physella integra
), and an aquatic prosobranch (Pleurocera canaliculatum). There was no
mortality in the pulmonates, but 39% mortality occurred in the prosob
ranch Pleurocera. Additionally, a sample of 43 zebra mussels (Dreissen
a polymorpha), a non-native but recently introduced species, were aeri
ally exposed to the same temperature cycle. Of the 43 mussels, 20 had
been acclimated to 2 degrees C, and 23 acclimated to 15 degrees C. Mor
tality occurred in both treatments (35% mortality in the 15 degrees C
acclimated and 25% in the 2 degrees C acclimated) and did not differ s
ignificantly between the two groups. No mortality occurred among contr
ols.