Critical thresholds in aquatic ecosystems: a case study of Tasmanian diatom community response to regional and local environmental change

No Thumbnail Available
Journal Title
Journal ISSN
Volume Title
Australian Society for Limnology
Aquatic ecosystems are often hyper-sensitive and rapid responders to local and regional environmental change, in large part, due to fast reproduction and short lifespans of organisms relative to, for example, terrestrial vegetation. Here, we explore the response of a local diatom community to rapid shifts in rainforest vegetation driven by climate and fire over the last 2,400 years. We use a suite of palaeolimnological data to determine changes in vegetation, nutrient cycling, sediment delivery and diatom community structure to test the response of the local aquatic ecosystems to climate-driven terrestrial environment changes. We find that the diatom community in our study lake, Lake Vera in southwest Tasmania, Australia, remains complacent through phases of substantial changes in the terrestrial environment, hinting at a degree of resilience to both regional climatic and local terrestrial ecosystem change. We also identify a major compositional changes in diatom community – a shift from a planktonic dominance (i.e. Discostella stelligera) to a benthic dominance (i.e. Fragilaria spp. and Achnanthes didyma) – at ca. 930 cal yr BP, prior to a climate-driven terrestrial ecosystem change at ca. 800 cal yr BP. This aquatic ecosystem state-shift reflects the crossing of a critical threshold/tipping point in response to regional drivers and/or local dynamics that, thus, provides critical insights in to the long-term drivers and responses of aquatic ecosystem dynamics.
Aquatic organisms, Aquatic ecosystems, Plankton, Diatoms, Lakes, Sediments, Limnology, Tasmania
Beck, K. K., Fletcher, M.-S., Saunders, K. M., Benson, A., Gadd, P., Heijnis, H., Wolfe, B. & Zawadzki, A. (2016). Critical thresholds in aquatic ecosystems: A case study of Tasmanian diatom community response to regional and local environmental change. Poster presentation at the Australian Society for Limnology Conference (ASL), 2016. Ballarat, 26 to 30 September 2016. Retrieved from: