Occurrence of zebra mussels in near-shore areas of western Lake Erie

We measured biomass, percent coverage, and length-frequency of zebra mussels in nearshore areas of western Lake Erie between 16 September and 10 November 1993 as part of a larger study on the ecological relationship between diving ducks and zebra mussels. Wet weight biomass of zebra mussels, determined by SCUBA diving, ranged from 0 to 3,611 g/m(2) and averaged (+/- 1 SE) 1,270 +/- 380 g/m(2) (n = 11). Percent coverage of lake bottom by zebra mussels ranged from 0 to 70% and averaged 17 +/- 4.0% (n = 27). Percent coverage of zebra mussels was relatively high in the northern portion (28-70% covet-age) and in the southwestern portion (18-40%), but relatively low (< 5%) in the southeastern portion of the study area. Percent coverage by zebra mussels, determined from underwater videography, was highly correlated (r(2) = 0.96) with zebra mussel biomass. Analysis of length-frequency data indicated that there was prominent recruitment of juvenile zebra mussels at only three of eight sites. Average shell length ranged from 11 mm to 15 mm at the other-five sites. The non-uniform distribution of zebra mussels, as determined from biomass and videography, may have important ramifications when assessing zebra mussel impacts on waterfowl. These data may also be used when assessing impact of zebra mussels on other aquatic organisms in the near-shore areas of western Lake Erie.