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Status of the Amphipod Diporeia spp. in Lake Superior, poster presentation
Citation:
SCHAROLD, J. V., J. R. KELLY, AND T. D. CORRY. Status of the Amphipod Diporeia spp. in Lake Superior, poster presentation. Presented at American Society of Limnology and Oceanography / North American Benthological Society Joint Meeting, Santa Fe, NM, June 06 - 11, 2010.
Impact/Purpose:
hese results suggest that the conditions causing the observed reductions in Diporeia populations of the lower Great Lakes are not present in Lake Superior.
Description:
The amphipod Diporeia has historically been the dominant benthic macroinvertebrate in deeper waters of the Laurentian Great Lakes. Although Diporeia populations in the lower Great Lakes have experienced severe declines in recent years, densities have remained relatively stable in Lake Superior. In 2006 we used a probability based sampling design to assess population density of Diporeia in Lake Superior. Diporeia were sampled at 52 sites using a Ponar grab. Thirty-five sites were in the nearshore (0-150m depth) stratum and 17 in the offshore (greater than 150m) stratum. The lake-wide mean density of Diporeia was 435 + 63(SE) m-2. In nearshore and offshore regions, mean densities were 856 + 112 m-2 and 158 + 29 m-2, respectively. These values are above the minimum objectives set by the Great Lakes Water Quality Agreement. The observed densities are also higher than those reported from the only previous comprehensive lake-wide survey of Diporeia populations, conducted in 1972. These results suggest that the conditions causing the observed reductions in Diporeia populations of the lower Great Lakes are not present in Lake Superior.