Seton and Anderson lakes are two morphologically and chemically similar fjord lakes located within the Fraser River Basin, British Columbia, Canada. Both lakes contain anadromous populations of Sockeye Salmon (Oncorhynchus nerka) and resident Kokanee (O. nerka, landlocked variant). The two lakes experience a common biogeoclimatic setting, yet contrasting turbid- water influences from a hydroelectric development. Seton Lake has experienced human-induced physical and chemical changes, largely due to the creation of dams and a large water diversion introducing glacially-turbid water to this historically clearwater system, whereas Anderson is not impacted by hydro-system management. As all existing limnological information on Seton Lake is constrained to the post-diversion period, the full extent of these influences on freshwater rearing conditions for salmon, and interactions with climate change remain largely unknown. This project focused on reconstructing the trophic ecology of the two lakes over the last ~500 years. The study employs a paleolimnological Before-After-Control-Impact (BACI) design (Stewart-Oaten et al. 1986), and is intended to assess the cumulative effects of the Bridge River Diversion and climate change on primary (i.e. diatoms) and secondary (i.e. cladoceran, zooplankton) trophic levels in Seton Lake to determine changes in food web productivity for sockeye salmon and kokanee.
Ciliates are unicellular heterotrophic organisms that play a key role in the planktonic and benthic food webs of lakes, and represent a great potential as bioindicator. In this study, we used the top-bottom paleolimnological approach to compare the recent and past (i.e. prior to major anthropogenic impacts) ciliate communities of 48 lakes located along an elevation gradient using metabarcoding techniques applied on sedimentary DNA (sed-DNA).
Microeukaryote communities ensure a large panel of ecological functions as autotrophs, predators, parasites, and saprotrophs, through which they provide various ecosystem services. Although they play an important role in freshwater ecosystems, microeukaryotes are still largely overlooked when studying the biological response of lakes to environmental changes. In this study, we used a sedimentary DNA (sedDNA) approach to understand the effect of eutrophication and climate change on microeukaryote communities of large peri-alpine lakes. Four lakes that displayed contrasting nutrient enrichment history, and that are now oligotrophic, were selected. The long-term dynamic, structure and biodiversity of microeukaryote communities and functional groups were reconstructed over the last 200 years. We assessed lake-specific ecological dynamics, resilience and resistance through various biological metrics, i.e. alpha and beta-diversity, trait-based functional community approach.