title: The widespread threat of calcium decline in fresh waters.
abstract: 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.
authors.affiliation: Paleoecological Environmental Assessment and Research Lab, Department of Biology, Queen's University, Kingston, ON, Canada, K7L 3N6.
authors.forename: Adam
authors.initials: A
authors.lastname: Jeziorski
authors.forename: Norman D
authors.initials: ND
authors.lastname: Yan
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Paterson
authors.forename: Anna M
authors.initials: AM
authors.lastname: Desellas
authors.forename: Michael A
authors.initials: MA
authors.lastname: Turner
authors.forename: Dean S
authors.initials: DS
authors.lastname: Jeffries
authors.forename: Bill
authors.initials: B
authors.lastname: Keller
authors.forename: Russ C
authors.initials: RC
authors.lastname: Weeber
authors.forename: Don K
authors.initials: DK
authors.lastname: McNicol
authors.forename: Michelle E
authors.initials: ME
authors.lastname: Palmer
authors.forename: Kyle
authors.initials: K
authors.lastname: McIver
authors.forename: Kristina
authors.initials: K
authors.lastname: Arseneau
authors.forename: Brian K
authors.initials: BK
authors.lastname: Ginn
authors.forename: Brian F
authors.initials: BF
authors.lastname: Cumming
authors.forename: John P
authors.initials: JP
authors.lastname: Smol
mesh_terms: 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*
chemical_list: D002118:Calcium