Alteration of Ecosystem Function by Zebra Mussels in Oneida Lake: Impacts on Submerged Macrophytes |
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Authors: | B Zhu D G Fitzgerald C M Mayer L G Rudstam E L Mills |
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Institution: | (1) Department of Biology, Syracuse University, 130 College Place, Syracuse New York, 13244, USA;(2) Department of Natural Resources, Cornell University Biological Field Station, Bridgeport New York, 13030, USA;(3) Present address: Department of E.E.E.S., University of Toledo, Lake Erie Center, 6200 Bayshore Road, Oregon, Ohio 43618, USA |
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Abstract: | Dreissenid mussels (the zebra mussel Dreissena polymorpha and the quagga mussel D. bugensis) are ecosystem engineers that modify the physical environment by increasing light penetration. Such a change is likely to
affect the distribution and diversity of submerged macrophytes. Filter-feeding by these mussels has been associated with increased
water clarity in many North American and European lakes. In this study, we report the increase in water clarity of Oneida
Lake, New York, USA, for 1975–2002 and argue that the increase was caused by zebra mussel invasion rather than declines in
nutrients. Over the study period, although mean total phosphorus decreased significantly, the main increase in water clarity
occurred after the zebra mussel invasion in 1991. The average depth receiving 1% surface light increased from 6.7 m to 7.8
m after the invasion of zebra mussels, representing a 23% areal expansion. The maximum depth of macrophyte colonization, as
measured by diver and hydroacoustic surveys, increased from 3.0 m before the invasion of zebra mussels to 5.1 m after their
establishment. In addition, macrophyte species richness increased, the frequency of occurrence increased for most species,
and the composition of the macrophyte community changed from low-light–tolerant species to those tolerating a wide range of
light conditions. Comparisons with observations reported in the literature indicate that increased light penetration alone
could explain these changes in macrophyte distribution and diversity. Such changes will increase the importance of benthic
primary production over pelagic production in the food web, thereby representing an overall alteration of ecosystem function,
a process we refer to as “benthification”. |
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Keywords: | submerged macrophytes dreissenid mussels light water clarity Secchi depth species diversity Oneida Lake |
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