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1. Identifying and applying new approaches to study ecological dynamics and drivers from lake sediments : Paleolimnology not only provides information on past environmental change (e.g., tracking shifts in lake water pH), but also offers key insights into biodiversity dynamics because community-level changes can be analysed over a broader network of sites and over longer time series than is possible with classical long-term ecological research programs. My lab group is applying both traditional paleolimnological methods and emerging molecular genetics tools to track the tempo of change in biodiversity and ecosystem functioning dynamics. For example, we have been studying the DNA from a wide variety of taxa that is preserved in lake sediments to generate data and knowledge on the long-term dynamics of a much broader range of organisms (Domaizon et al. 2017, Pilon et al. 2019; Gauthier et al. in revision). To get a clearer perspective on the strength and limitations of analyses of sedDNA (DNA extracted from lake sediments), we are conducting a series of short-term sediment trap and surface sediment studies as well as analyses of sediment cores from lakes with well-established histories. This work is being complemented by traditional studies of subfossils as well as high-resolution, core scanner time series.
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Sediment traps, as setup here, are used to track real-time/short-term lake dynamics by capturing sediments as they fall to the lake bottom. Cladoceran subfossils and diatoms, as well as sediment environmental DNA can be used in both sediment traps and cores.
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Numerous members of our lab are part of the NSERC LakePulse network and contributing to the first national assessment of lake health; and some are also affiliated with a sister FRQNT-funded Team grant. Our work under this theme is primarily focused on developing analyses of classical (diatoms and zooplankton) or emerging biodindicators (based on metabarcoding or metagenomics) sampled in the water column and sediment records. We are also conducting geochemical analyses (heavy metals) in partnership with collaborators. A summary of the overall project is described in Huot et al. (2019) and papers on this topic are now starting to be submitted. You can also check out the NSERC LakePulse website (www.lakepulse.ca) to learn what’s happening across the network.
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Map of lakes sampled in 2017, 2018 and 2019. In the map above, for each lake, the size of the circle indicates one of our three size classes (small is 0.1-0.5 km2, medium is 0.5- 5 km2, large is 5-100 km2). The colour indicates our human impact index (green is low, yellow is moderate, red is high; described in Huot et al. 2019). Interactive map available at www.lakepulse.ca
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From Taranu et al. 2015 Ecology Letters: Map of Northern Hemisphere highlighting sediment core sites (n = 108) and their historical trends in sedimentary cyanobacterial pigment concentrations. Fill colours show the strength of cyanobacterial (myxoxanthophyll) trends through time determined by the Mann–Kendall (M-K) test, where green tones correspond to positive M-K trends and blue tones to negative ones.
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