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Science 28 November 2008:
Vol. 322. no. 5906, pp. 1374 - 1377
DOI: 10.1126/science.1164949
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Reports
The Widespread Threat of Calcium Decline in Fresh Waters
Adam Jeziorski,1
Norman D. Yan,2,3
Andrew M. Paterson,3
Anna M. DeSellas,1,3
Michael A. Turner,4
Dean S. Jeffries,5
Bill Keller,6
Russ C. Weeber,7
Don K. McNicol,7
Michelle E. Palmer,2
Kyle McIver,1
Kristina Arseneau,1
Brian K. Ginn,1
Brian F. Cumming,1
John P. Smol1*
Calcium concentrations are now commonly declining in softwater boreal lakes. Although the mechanisms leading to these declines are generally well known, the consequences for the aquatic biota have not yet been reported. By examining crustacean zooplankton remains preserved in lake sediment cores, we document near extirpations of calcium-rich Daphnia species, which are keystone herbivores in pelagic food webs, concurrent with declining lake-water calcium. A large proportion (62%, 47 to 81% by region) of the Canadian Shield lakes we examined has a calcium concentration approaching or below the threshold at which laboratory Daphnia populations suffer reduced survival and fecundity. The ecological impacts of environmental calcium loss are likely to be both widespread and pronounced.
2 Department of Biology, York University, 4700 Keele Street, Toronto, ON, Canada, M3J 1P3.
3 Ontario Ministry of the Environment, Dorset Environmental Science Centre, 1026 Bellwood Acres Road, Post Office Box 39, Dorset, ON Canada, P0A 1E0.
4 Experimental Lakes Area, Fisheries and Oceans Canada, 501 University Crescent, Winnipeg, MB, Canada, R3T 2N6.
5 Environment Canada, National Water Research Institute, Post Office Box 5050, Burlington, ON, Canada, L7R 4A6.
6 Ontario Ministry of the Environment, Cooperative Freshwater Ecology Unit, Laurentian University, Sudbury, ON, Canada, P3E 2C6.
7 Canadian Wildlife Service (Ontario), Environment Canada, 335 River Road, Ottawa, ON, Canada, K1A 0H3.
* To whom correspondence should be addressed. E-mail: smolj{at}queensu.ca
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