Sensitivity to aerial exposure: Potential of drawdowns to manage zebra mussels

Tucker, J. K., C. H. Theiling, F. J. Janzen, and G. L. Paukstis. 1997. Sensitivity to aerial
exposure: Potential of system-wide drawdowns to manage zebra mussels in the Mississippi
River. Regulated Rivers: Research & Management 13:479 487. Reprinted by U.S.
Geological Survey, Environmental Management Technical Center, Onalaska, Wisconsin,
May 1998. LTRMP 98-R009. 9 pp. (NTIS PB98-157852)


ABSTRACT

We report the results of five experiments performed during periods of lowered river water
level in Pool 26 of the Mississippi River. Four experiments compared survivorship of zebra
mussels (Dreissena polymorpha) and unionid mussels (Unionidae). Under mild spring
conditions (March), survivorship of zebra mussels was similar to that of unionid mussels,
but during summer (July) survivorship of zebra mussels was lower than that of unionid
mussels. Survivorship of zebra mussels was greatest when attached to native unionids,
compared with detached zebra mussels and zebra mussels attached rocks. A fifth
experiment compared survivorship of 10 species of unionid mussels after 24 hours of aerial
exposure. In general, survivorship of thick-shelled species, such as Amblema plicata, was
greater than survivorship of thin-shelled species, such as Potamilus ohiensis. The
experiments conducted suggest that drawdowns during warm summer conditions could
have a profound, negative influence on zebra mussel demography and distribution. In
contrast, unionid mussel survival was unaffected by aerial exposure of up to 24 hours
during a midsummer drawdown.


KEYWORDS

Aerial exposure, Mississippi River, survivorship, unionid mussels, zebra mussels