Calcium levels in Emphasis Type="Italic"Daphnia

Authors: Adam Jeziorski Andrew M Paterson Norman D Yan John P Smol

Publish Date: 2007/06/01

Volume: 39, Issue: 3, Pages: 421-425

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Abstract

Despite reductions in atmospheric sulphur emissions and the resulting decline in acidic deposition many lakes on the Canadian Shield that have experienced acidification are either recovering at a rate slower than expected or not recovering at all This lack of recovery is believed to be partly the consequence of the depletion of exchangeable base cations principally calcium Ca from watershed soils Although the implications of reduced Ca availability for biological communities remain poorly understood the effects on crustacean zooplankton populations may be severe as Ca is the primary structural component of the crustacean zooplankton exoskeleton Because the daphniid resting egg is protected by a modified portion of the exoskeleton ephippia and because these ephippia are well preserved in lake sediments we investigated whether interspecific differences in Ca content are recoverable from Daphnia ephippia However using two methods we did not find a recoverable Ca signal in the ephippia indicating that future efforts should be focused upon sedimentary taxonomic assemblage differences not differences in ephippial Ca levelsWe thank A Cairns and M CelisSalgado at the Dorset Environmental Science Centre’s FLAMES lab for providing the cultured daphniid samples and E Just for her invaluable help during the SEM analysis This project was funded through a Natural Sciences and Engineering Research Council grant to JP Smol as well as a Memorandum of Understanding between the Ontario Ministry of the Environment and J P Smol

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