Arctic warming drives striking twenty-first century ecosystem shifts in Great Slave Lake (Subarctic Canada), North America's deepest lake

Abstract

Great Slave Lake (GSL), one of the world's largest and deepest lakes, has undergone an aquatic ecosystem transformation in response to twenty-first-century accelerated Arctic warming that is unparalleled in at least the past two centuries. Algal remains from four high-resolution palaeolimnological records retrieved from the West Basin provide baseline limnological data that we compared with historical phycological surveys undertaken on GSL between the 1940s and 1990s. We document the rapid restructuring of algal community composition ca 2000 CE that is consistent with recent increases in regional air temperature and declines in ice cover and wind speed, that collectively altered habitats for aquatic biota. This new limnological regime initiated the first observation of scaled chrysophytes and favoured the rapid proliferation of small planktonic cyclotelloid diatoms which replaced the long-established dominance of large filamentous Aulacoseira islandica in West Basin sedimentary records. Such abrupt transformations in the primary producers of this socioecologically valuable ‘northern Great Lake’ may have widespread implications for the entire food web with unknown consequences for aquatic ecosystem functioning and fisheries, which First Nations, Métis and other northern communities depend upon, pointing to the need for new studies.

A framework for integrated monitoring of status and trends in water balance, water chemistry and contamination of shallow lakes across a remote dynamic freshwater delta

“…These and other successful long-term freshwater ecosystem monitoring programs typically are situated in regions where population density and infrastructure are substantial (including road access to sampling sites), and where there is adequate availability of well-trained personnel and long-term commitment of funding [25]. Substantial challenges exist, however, for aquatic ecosystem monitoring within remote lake-rich landscapes, such as in northern Canada, Alaska, and Russia, where concern has been mounting over ecosystem degradation by climate change and expansion of industrial activities [26][27][28][29][30]. The challenges include, but are not limited to, logistical and financial barriers associated with access to remote sampling sites, local capacity to maintain monitoring activities, insufficient availability of data to inform selection of approaches, and contrasting priorities of a diverse set of stakeholders and rightsholders.…”

Nonlinear responses in interannual variability of lake ice to climate change

“…Increasing variability may provide an early-warning signal for reaching a new stable state (Scheffer et al 2009). Thus, documenting changes in the variability of ice cover is critical for understanding how lakes are responding to climate change (Rühland et al 2023), as ice on lakes plays an important role in numerous physical and ecological lake processes in winter and throughout the rest of each year (Hampton et al 2017;Hébert et al 2021;Jansen et al 2021).…”