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Survival of zebra mussels (dreissena polymorpha) and asian clams (corbicula fluminea) under extreme hypoxia

Abstract : Zebra mussels (Dreissena polymorpha) and Asian clams (Corbicula flurninea) were exposed to acute hypoxia (P0 sub 2 < 5 torr or 3 percent of full air oxygen saturation) in order to determine anoxia tolerance and assess O2 as an efficacious, nonchemical, environmentally neutral, macrofouling control strategy. Zebra mussels were collected from Black Rock Navigation Lock on the Niagara River in Buffalo, NY, and Asian clams from the U.S. Army Corps of Engineers, Aquatic Ecosystems Research Facility, Lewisville Lake, Denton County, TX. Adults of both species were acclimated to 5, 15, or 25 deg C for 14 days prior to anoxia tolerance testing. After acclimation, paired samples of 30 individuals from each acclimation group were placed in separate 5-l air tight plastic containers (22 cm by 22 cm by 12 cm) with 4 l of dechlorinated tap water, leaving a gas head-space of 1 l. Paired samples of both species were held in either aerated (control) or anaerobic water (treatment), which was made anoxic by continuous gassing with N2, and held at test temperatures of either 15 or 25 deg C. Medium O2 concentrations and mortality were recorded daily. Dead individuals were removed and their shell lengths (SL) measured to the nearest 0.1 mm. Container medium was replaced every three days with previously deoxygenated or oxygenated water at the test temperature as appropriate. Negligible mortality (<3 percent) was recorded in all aerated control samples of both species. -BKA