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The endemic spring snail Pyrgulopsis montezumensis in a high CO 2 environment: Importance of extreme chemical habitats as refugia
Author(s) -
O’Brien Chris,
Blinn Dean W.
Publication year - 1999
Publication title -
freshwater biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.297
H-Index - 156
eISSN - 1365-2427
pISSN - 0046-5070
DOI - 10.1046/j.1365-2427.1999.444475.x
Subject(s) - dissolved organic carbon , invertebrate , ecology , spring (device) , habitat , limnetic zone , gastropoda , predation , biology , environmental chemistry , chemistry , mechanical engineering , littoral zone , engineering
1. We examined the distribution of the endemic spring snail, Pyrgulopsis montezumensis , along a gradient of dissolved free CO 2 and on selected substrata in the collapsed travertine springmound of Montezuma Well, Arizona, U.S.A. 2. Dissolved CO 2 concentration ranged from 480 (SE ± 56) mg L −−1 near the bottom spring vents in the limnetic zone (12 m deep) of the well to < 20 mg L −−1 in an irrigation canal about 1400 m downstream from the well outlet. Spring snails occurred in habitats with 110–315 mg L −−1 dissolved CO 2 . 3. Laboratory experiments showed that P . montezumensis tolerated a dissolved CO 2 concentration up to about 400 mg L −−1 for 11 days, but displayed 40% (SE ± 4) mortality after 3 days at 728 mg L −−1 and 100% mortality after 24 h at 1200 mg L −−1. We also measured 100% mortality after 10 days at ambient concentrations (< 10 mg L −−1 ) of dissolved CO 2 . 4. Although the concentration of dissolved CO 2 was within the tolerance range for spring snails in the irrigation canal, inadequate substrata and increased predation probably restricted their distribution in the lower reaches of the canal. Both field measurements and laboratory selection experiments showed a significant ( P < 0.001) preference for limestone substrata over submerged vegetation and fine sediments. 5. We propose that springs with high dissolved CO 2 may provide refugia from invertebrate and/or vertebrate predators not physiologically adjusted to the extreme chemical environment. These extreme chemical habitats probably reduce competition for resources and predation and allow resistant populations like P . montezumensis to attain high density.