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The effect of calcium concentration on the calcification of Daphnia magna
Author(s) -
Alstad Nina E. W.,
Skardal Liz,
Hessen Dag O.
Publication year - 1999
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1999.44.8.2011
Subject(s) - daphnia magna , moulting , calcium , calcification , zoology , daphnia , invertebrate , cladocera , crustacean , dry weight , environmental chemistry , chemistry , biology , ecology , toxicity , botany , medicine , organic chemistry , larva
Soft waters are characterized by low Ca concentrations, and the distribution and relative success of Ca‐demanding invertebrates could be limited by low Ca in extreme softwater localities. A further Ca depletion caused by reversed acidification could thus seriously affect freshwater crustaceans. Experimental studies on the calcification and Ca content of Daphnia magna clearly suggested the potential of a Ca limitation. Saturated calcification was reached at Ca concentrations >0.13 mM. Individuals reared in media with lower Ca concentrations were unable to compensate by increasing the period of postmolt Ca uptake and thus had a lower specific Ca content. Specific Ca content decreased from 4.2% to 1% of dry weight over the range 0.25–0.013 mM Ca. Even at the low Ca concentrations, only 10% of total Ca was reclaimed upon molting, the rest was lost with the old exuviae (∼40%) or to the ambient medium (∼50%). This incomplete calcification under low ambient Ca concentrations could represent a competitive drawback in Ca‐poor waters.