OCCURRENCE OF ZEBRA MUSSELS IN NEAR-SHORE AREAS OF WESTERN LAKE ERIE

We measured biomass, percent coverage, and length-frequency of zebra m ussels in nearshore areas of western Lake Erie between 16 September an d 10 November 1993 as part of a larger study on the ecological relatio nship between diving ducks and zebra mussels. Wet weight biomass of ze bra 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 covera ge of lake bottom by zebra mussels ranged from 0 to 70% and averaged 1 7 +/- 4.0% (n = 27). Percent coverage of zebra mussels was relatively high in the northern portion (28-70% covet-age) and in the southwester n portion (18-40%), but relatively low (< 5%) in the southeastern port ion of the study area. Percent coverage by zebra mussels, determined f rom underwater videography, was highly correlated (r(2) = 0.96) with z ebra mussel biomass. Analysis of length-frequency data indicated that there was prominent recruitment of juvenile zebra mussels at only thre e of eight sites. Average shell length ranged from 11 mm to 15 mm at t he other-five sites. The non-uniform distribution of zebra mussels, as determined from biomass and videography, may have important ramificat ions when assessing zebra mussel impacts on waterfowl. These data may also be used when assessing impact of zebra mussels on other aquatic o rganisms in the near-shore areas of western Lake Erie.