Description: Our lab has been working across the circum-polar Arctic for four decades, with a primary focus on the limnology and paleolimnology of these often poorly described waterbodies. Diatoms have been the primary indicators of ecosystem change. As reviewed in Chapter 4 of my recent book (Smol 2023), our early research focused on small ponds. Beginning with our first paleolimnological study that demonstrated this comparative approach in the High Arctic (Douglas et al. 1994, Science) to our continuing work, we argue that recent ecological shifts are unprecedented, at least over the Holocene, and that climate warming is the primary driver of these changes. Whilst a considerable amount of paleolimnological data have now been gathered from small and mid-sized lakes, little comparable data are available on even the basic limnological conditions of the “Northern Great Lakes”. In this talk, I will compare diatom changes, over the last ~200 years, for Lake Hazen (Lehnherr et al. 2018, Nature Comm., Michelutti et al. 2020, Proc. Roy. Soc. Lond.), Great Slave Lake (Rühland et al. 2023, Proc. Roy. Soc. Lond.), and Great Bear Lake (Rühland et al. unpublished) and compare these to changes observed in nearby medium and small-sized lakes. A clear continuum of predictable changes shows that climate thresholds (e.g. ice cover loss, thermal stratification) have recently been surpassed. These changes will undoubtedly cascade throughout the ecosystem affecting food web changes important to local Indigenous populations and to the global community.

Smol, J.P. 2023. Lakes in the Anthropocene: Reflections on tracking ecosystem change in the Arctic. Excellence in Ecology Book Series, International Ecology Institute (ECI), Oldendorf/Luhe, Germany. 13 chapters. 438 pp. 50 Euros plus postage.