Climate change presents complex and uncertain future scenarios in the world's Great Lakes. Major abiotic changes have direct and indirect effects on lake food webs; the nature and extent of such past, present and projected food web changes may be better understood through the analysis of long-term ecological data sets. An excellent opportunity for such analyses exists for subarctic Lake Baikal, the world's most ancient, voluminous, and biologically diverse lake. We have employed several approaches to analyze 60 years of biweekly data collected by 3 generations of a single family of Siberian scientists, in order to understand climate-associated changes occurring among the plankton that constitute the base of the food web. By applying Time-Frequency analysis, we created two distinct opportunities for analysis: 1) a “de-seasoned” abiotic and biotic data set in which to explore species interactions and responses to larger scale climatic variables, and 2) a time series of transformation properties such as phase of key harmonics, which describe large-scale trends in lake seasonality. With de-seasoned data, we employed multivariate autoregressive (MAR) modeling to explore species interactions in the food web, as well as biotic relationships with temperature and climate indices that can proxy for other climatic variables. Warming was strongly correlated with compositional changes in the plankton, shifts that may affect the manner in which nutrients cycle in the lake. Warming has been accompanied by reduction in ice cover and by increasing depth of the mixed layer of water near the surface, both further altering the physical environment in which Lake Baikal's native cold-adapted biota interact. In addition to the strong long-term warming trend over the past 60 years, we found that seasonality correlates with large-scale climate indices, suggesting that the lake temperature data closely track the dynamics of the jet stream across Siberia.
Keywords: Global warming; Limnology; Multivariate; Long-term ecological research
Biography: Stephanie Hampton is an aquatic ecologist whose research focuses on the analysis of long-term freshwater and marine data sets, with a current emphasis on understanding environmental responses to climate change. Since 2006 she has been Deputy Director of the National Center for Ecological Analysis and Synthesis at the University of California, Santa Barbara. NCEAS is a research center that relies exclusively on generating knowledge from existing information about the environment, rather than gathering new data, a unique approach that propelled NCEAS into the top tier of scientific impact within 10 years of the Center's establishment in 1995. Prior to her arrival at NCEAS, Dr. Hampton was on faculty in the College of Natural Resources at the University of Idaho.