Jamie Would MSc Student, Smol Lab Tracking long-term changes in climate and salinity using cladoceran and other markers from saline lakes in Yukon In the Canadian sub-Arctic, inland saline (athalassic) lakes are rare, as they are typically only found in temperate or equatorial regions with arid climates. These lakes, characterized by unusually high salinities and shallow, closed-basin morphometries, are especially sensitive to climate change as salinity increases markedly with increased evaporation. However, due to their remote location, little is known about the ecology of northern athalassic lake systems and their responses to climate warming. Here, we used paleolimnological approaches to reconstruct multi-trophic level responses to climate warming using biological, chemical and physical information preserved in dated lake sediments. Siliceous algae indicated increasing salinity since the early 1900s, closely tied to rising air temperatures. Cladoceran (commonly known as water fleas) microfossils, representing intermediate-trophic levels, tracked declines in species diversity with increasing salinity. Interestingly, a major lake drawdown (for road maintenance) between 1948 and the mid-1970s did not affect cladoceran assemblage composition (but did result in a change in diatom composition), allowing us to independently separate the effects of lake salinization and water level changes. This research sheds light on the impact of climate-induced salinization on northern lake ecosystems and also demonstrates the value of cladoceran microfossils as paleolimnological indicators of salinity.
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