Effects of temperature and temkperature acclimation on survival of zebra mussels (Dreissena Polymorpha) and asian clams (Corbicula Fluminea) under extreme hypoxia

摘要

Following acclimation to 5 deg. 15 deg or 25 deg C for 14 days, samples of 30 Dreissena polymorpha (zebra mussels) and Corbicula fluminea (Asian clams) were held in either aerated (control) or extremely hypoxic N_2 gassed water (PO2 < 3% of full air saturation). Mortality was negligible in all aerated controls. Mean hypoxia tolerance in D. polymorpha ranged from 3-4 days at 25 deg C to 38-42 days at 5 deg C. Hypoxia tolerance time of zebra mussels increased significantly with declining test temperature (P < 0.001) and increasing acclimation temperature (P < 0.001). Larger zebra mussels were more tolerant than smaller individuals. Asian clams were 2-7 times more tolerant of hypoxia than zebra mussels, Surviving a mean of t 1.8 and 35.1 days at 25 deg C and 15 deg C, respectively, and without mortality for 84 days at 5 deg C. and were not influenced by temperature acclimation. At 25 deg C. larger specimens of Asian clams were loss tolerant of hypoxia than smaller individuals. Both species are amongst the least hypoxia tolerant freshwater bivalve molluscs, reflecting their prevalence in well-oxygenated shallow water habitats. Prolonged exposure to extreme hypoxia may provide an efficacious control strategy, particularly for D. polymorpha.