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Strayer, D.L., and L.C. Smith, 1996. Relationships Between Zebra Mussels (Dreissena
polymorpha) and Unionid Clams During the Early Stage of the Zebra Mussel Invasion of
the Hudson River, Institute of Ecosystem Studies
Reprinted with Permission from Freshwater
Biology
(1996) 36: 771-779
Relationships Between Zebra Mussels (Dreissena polymorpha)
and Unionid Clams During the Early Stage of the Zebra Mussel Invasion of the Hudson River
SUMMARY
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We monitored the density, recruitment and
condition (body mass at a given shell length) of unionid clams in the freshwater tidal
Hudson River before and during the early years of the zebra mussel (Dreissena polymorpha)
invasion of the river. Zebra mussels were first seen in the river in 1991 and were
dominant by the end of 1992.
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Despite high densities of zebra mussels in the Hudson, only 30% of the unionids were
infested with zebra mussels, far fewer than predicted by published models of zebra
mussel-unionid interactions. We do not know why so few unionids were colonized.
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After the arrival of the zebra mussel, densities of unionid clams fell by 56%,
recruitment of young-of-the-year unionids fell by 90%, and condition of unionids fell by
20-50%. These changes occurred in all three of the common unionid species in the river.
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Elliptio complanata appears to have been less severely affected by the zebra mussel
than were Anodonta implicata and Leptodea ochracea, judging by declines in
density, recruitment and condition.
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Our results suggest that unionids may be affected by zebra mussels by competition for
food as well as by fouling.
Entire Paper
Contact: D.L. Strayer, Institute of Ecosystem Studies, Box AB, Millbrook, NY
12545
Keywords: Zebra_mussel, Ecological_interactions,
Environmental_impact
Product Type: Research,
Impact
User Type: General
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