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Resistance to drought affects persistence of alternative regimes in shallow lakes of the Boreal Plains (Alberta, Canada)
Author(s) -
Cobbaert Danielle,
Wong Agnes S.,
Bayley Suzanne E.
Publication year - 2015
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 - 10.1111/fwb.12633
Subject(s) - persistence (discontinuity) , boreal , ecology , resistance (ecology) , taiga , geography , drought resistance , environmental science , biology , geology , agronomy , geotechnical engineering
Summary We examined how lake and landscape factors affected the persistence of alternative regimes in 23 predominantly fishless, shallow lake ecosystems over seven years in the Boreal Plains, Alberta, Canada. The alternative regimes were dominance by SAV (submerged aquatic vegetation) or by phytoplankton. The relationship between alternative regime persistence and a suite of lake and landscape variables were determined using regression tree analysis. We also compared the environmental variables and biological communities among alternative regimes using Kruskal–Wallis nonparametric tests and post hoc tests. Persistence of the SAV ‐rich regime was best predicted by water level stability. Switches from a SAV ‐rich regime to a phytoplankton‐rich regime have been attributed to drought, which concentrates total phosphorus ( TP ) and other solutes and increases turbidity, favouring phytoplankton dominance. Lakes with stable water levels are inferred as less sensitive to drought, and presumably experience less evapoconcentration during drought, which helps maintain the SAV ‐rich regime. Lakes with more water level drawdown may also delay or inhibit SAV growth through physical disturbance. In contrast, the persistence of the phytoplankton‐rich regime was highest in lakes with higher TP and a lower proportion of surrounding wetlands. We postulate that lakes with less wetland in the buffer are more responsive to variations in precipitation because these systems have a smaller water storage capacity and lack peatlands that otherwise attenuate the effects of drought via shallow groundwater inputs. The relative persistence of lakes in the study area was related to lake and landscape factors that affect the relative sensitivity of the lakes to drought conditions. The biological community in these predominantly fishless lakes appears to play a weak role in maintaining the alternative regimes compared to fish‐bearing lake systems.