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The influence of calcium decline and climate change on the cladocerans within low calcium, circumneutral lakes of the Experimental Lakes Area.

Authors :
Jeziorski, Adam
Paterson, Andrew M.
Watson, Ian
Cumming, Brian F.
Smol, John P.
Source :
Hydrobiologia; Jan2014, Vol. 721 Issue 1, p129-142, 14p
Publication Year :
2014

Abstract

Calcium (Ca) concentrations of many softwater lakes on the Canadian Shield have been in decline for decades as a response primarily to regional acid deposition and repeated cycles of forest harvesting. These Ca declines are of ecological interest, as many lakes have fallen to Ca levels detrimental to the fitness of ecologically important Ca-rich cladoceran taxa such as Daphniapulex. However, distinguishing the impacts of reduced Ca from acidification (i.e., decreasing pH) on Ca-demanding fauna has proven difficult due to strong correlations between pH and Ca in softwater lakes. Here, we examine cladoceran sedimentary assemblages from low Ca lakes (mean present-day Ca < 2.0 mg l <superscript>−1</superscript>) in the Experimental Lakes Area (ELA) of Ontario, Canada, where Ca concentrations have declined since the 1980s, despite being closed to forestry and remote from (i.e., not downwind of) major sources of acid deposition. Differences between present-day and pre-industrial cladoceran assemblages were greatest among planktonic taxa, including Bosmina spp. and Holopedium glacialis. However, daphniid remains were present in only three of the ten study lakes with minimal directional trends. Overall, in these ELA lakes, daphniid abundance was low historically, and impacts possibly attributable to Ca declines have been obscured by the effects of regional climate warming. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
00188158
Volume :
721
Issue :
1
Database :
Complementary Index
Journal :
Hydrobiologia
Publication Type :
Academic Journal
Accession number :
92047588
Full Text :
https://doi.org/10.1007/s10750-013-1691-6