Survivorship of Aerially-Exposed Zebra Mussels (Dreissena polymorpha) under Laboratory Conditions

ABSTRACT

Zebra mussels (Dreissena polymorpha) were aerially exposed at temperatures of 5 C and 20 C for 12, 24, 36, and 60 h. Survivorship was nearly 100% in all control containers and for the 5 C replicates but declined substantially in the 20 C replicates after 36 and 60 h. Additional zebra mussels were aerially exposed at 5 C and 20 C on both wet and dry substrates for 60 h. Those aerially exposed on a wet substrate at 5 C had greater survivorship than did mussels on a dry substrate at 20 C. Larger zebra mussels (shell length > 16 mm) were significantly more likely to survive exposure for 36 or 60 h at 20 C than were smaller individuals. These results show that survivorship of freshly-collected zebra mussels under controlled, biologically-relevant conditions is strongly affected by length of aerial exposure, ambient temperature, substrate moisture, and mussel size. Our findings largely confirm results of companion field experiments, implying that temperature and moisture conditions caused the observed zebra mussel mortality in nature. Taken together, these studies suggest that aerial exposure at warm temperatures (≥ 20 C) may be an effective control for zebra mussels in regulated waters where water levels can be lowered for more than 24 h.