Reorganization of algal communities in the Lake of the Woods (Ontario, Canada) in response to turn‐of‐the‐century damming and recent warming

Abstract

Paleolimnological approaches were used to assess the ecological and environmental implications of diatom assemblage compositional changes recorded over the last , 200 yr from four sites in the Lake of the Woods (LoW), Ontario, Canada. Comparisons between a reference site (Whitefish Bay) and three disturbed sites (Bigstone Bay, Paleolimnological Project site No. 1, and Forrest Island) provide insights into the effects that multiple stressors (dam construction, total phosphorus [TP] changes, and recent warming) have had on the ecology of this highly complex freshwater system. Overall patterns of diatom compositional changes from highresolution 210 Pb-dated sediment cores revealed a strong temporal coherence ca. 1910 and then again over the last few decades among all sites. Hydromanagement activities at the turn of the 19th century and recent warming over the last few decades played key roles in the LoW diatom changes. Diatom compositional changes at all sites were significantly related to trends in nearby air temperature records over the past century and to changes in lake ice phenology over the past , 40 yr from Whitefish Bay. Turn-of-the-century hydromanagement activities do not appear to have had long-term effects on diatom-inferred TP (DI-TP), particularly at the disturbed sites. Clear decreases in DI-TP over the last few decades were evident at all sites, but at the reference site these decreases were well below pre-disturbance levels, which we link in part to recent warming. Substantial changes in climate will amplify the effects of multiple stressors on lake water properties that have major implications on algal communities.

Legacy of a half century of Athabasca oil sands development recorded by lake ecosystems

“…As a consequence of climate warming, the physical processes that lakes experience can be altered. Longer ice-free season and enhanced thermal stability, coupled with higher surface-water temperatures and the redistribution of nutrients within the water column, contribute to greater algal production within many lake ecosystems (38,39). Paleolimnological studies from a suite of lakes in Alberta (29,36) and the adjacent Northwest Territories (40) record notable shifts in lake primary production, influenced to some degree by climatic control.…”

Effects of Climate Change on Lake Thermal Structure and Biotic Response in Northern Wilderness Lakes

“…Recent studies have documented a series of possible climate-induced changes in boreal-region lakes, including a longer ice-free season [4][5][6][7], stronger or weaker thermal stratification [8,9], increased inputs of dissolved organic carbon and increased carbon burial [2,10], shifts in algal communities [1], and an increased frequency of cyanobacterial blooms [3]. These changes have been noted in remote lakes far removed from direct human disturbance, with the strongest evidence coming from the …”

Spatial, Environmental, and Biotic Determinants of Zooplankton Community Composition in Subarctic Lakes and Ponds in Wapusk National Park, Canada

“…Small diatoms and buoyant cyanobacteria have a distinct competitive advantage during periods of relative stability in lakes, as they experience reduced sinking velocities (Paerl, 1988;Winder et al, 2008) and may be able exploit subsurface habitats in the metalimnia of stratified lakes where nutrients are elevated (Fahnenstiel and Glime, 1983;Rühland et al, 2010). In our study, the deeper inland lakes showed evidence of weak to moderate stratification and, in at least one year (2001; described in Gunn and Snucins, 2010), strong thermal stratification has been observed in August in Hawley Lake.…”