The widespread threat of calcium decline in fresh waters.
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.
Jeziorski
Adam
A
Paleoecological Environmental Assessment and Research Lab, Department of Biology, Queen's University, Kingston, ON, Canada, K7L 3N6.
Yan
Norman D
ND
Paterson
Andrew M
AM
Desellas
Anna M
AM
Turner
Michael A
MA
Jeffries
Dean S
DS
Keller
Bill
B
Weeber
Russ C
RC
McNicol
Don K
DK
Palmer
Michelle E
ME
McIver
Kyle
K
Arseneau
Kristina
K
Ginn
Brian K
BK
Cumming
Brian F
BF
Smol
John P
JP
D000818:Animals; D002118:Calcium / Q000032:analysis*; D003621:Daphnia / Q000502:physiology*; D017753:Ecosystem; D020387:Food Chain; D005618:Fresh Water / Q000737:chemistry*; D019015:Geologic Sediments; D006863:Hydrogen-Ion Concentration; D009864:Ontario; D011157:Population Dynamics; D012098:Reproduction; D015048:Zooplankton / Q000502:physiology*
D002118:Calcium