Multiple anthropogenic stressors cause ecological surprises in boreal lakes

The number of combinations of anthropogenic stressors affecting global change is increasing; however, few studies have empirically tested for their interactive effects on ecosystems. Most importantly, interactions among ecological stressors generate nonadditive effects that cannot be easily predicted based on single-stressor studies. Here, we corroborate findings from an in situ mesocosm experiment with evidence from a whole-ecosystem manipulation to demonstrate for the first time that interactions between climate and acidification determine their cumulative impact on the food-web structure of coldwater lakes. Interactions among warming, drought, and acidification, rather than the sum of their individual effects, best explained significant changes in planktonic consumer and producer biomass over a 23-year period. Further, these stressors interactively exerted significant synergistic and antagonistic effects on consumers and producers, respectively. The observed prevalence of long- and short-term ecological surprises involving the cumulative impacts of multiple anthropogenic stressors highlights the high degree of uncertainty surrounding current forecasts of the consequences of global change.

[1]  R. Peters,et al.  LINKING PLANKTONIC BIOMASS AND METABOLISM TO NET GAS FLUXES IN NORTHERN TEMPERATE LAKES , 1999 .

[2]  M. Bothwell,et al.  Ecosystem Response to Solar Ultraviolet-B Radiation: Influence of Trophic-Level Interactions , 1994, Science.

[3]  Ed Snucins,et al.  Interannual variation in the thermal structure of clear and colored lakes , 2000 .

[4]  L. Rothschild,et al.  Life in extreme environments , 2001, Nature.

[5]  C. Williamson,et al.  Interactive effects of temperature and nutrient limitation on the response of alpine phytoplankton growth to ultraviolet radiation , 2005 .

[6]  A. Davis,et al.  Synergistic effects associated with climate change and the development of rocky shore molluscs , 2005 .

[7]  M. Rosenzweig,et al.  Species Diversity in Space and Time , 1995 .

[8]  L. Hansen,et al.  INTERACTIONS BETWEEN UV RADIATION AND TEMPERATURE LIMIT INFERENCES FROM SINGLE‐FACTOR EXPERIMENTS 1 , 2003 .

[9]  N. Pace.  A molecular view of microbial diversity and the biosphere. , 1997, Science.

[10]  T. Tschaplinski,et al.  Importance of changing CO2, temperature, precipitation, and ozone on carbon and water cycles of an upland‐oak forest: incorporating experimental results into model simulations , 2005 .

[11]  C. Williamson,et al.  Temperature‐dependent ultraviolet responses in zooplankton: Implications of climate change , 2002 .

[12]  Frederick J. Wrona,et al.  The influence of temperature and food chain length on plankton predatorprey dynamics , 1997 .

[13]  D. Schindler.  A DIM FUTURE FOR BOREAL WATERS AND LANDSCAPES , 1998 .

[14]  R. Vinebrooke,et al.  Effects of experimental greenhouse warming on phytoplankton and zooplankton communities in fishless alpine ponds , 2004 .

[15]  R. Paine,et al.  Compounded Perturbations Yield Ecological Surprises , 1998, Ecosystems.

[16]  M. Loreau,et al.  Biodiversity and ecosystem productivity in a fluctuating environment: the insurance hypothesis. , 1999, Proceedings of the National Academy of Sciences of the United States of America.

[17]  J. Elser,et al.  Zooplankton effects on phytoplankton in lakes of contrasting trophic status , 1991 .

[18]  I. Davison.  ENVIRONMENTAL EFFECTS ON ALGAL PHOTOSYNTHESIS: TEMPERATURE , 1991 .

[19]  J. Downing,et al.  Biodiversity and stability in grasslands , 1996, Nature.

[20]  J. Gillooly,et al.  Effect of body size and temperature on generation time in zooplankton , 2000 .

[21]  M. Moore,et al.  Synergism and antagonism among multiple stressors , 1999 .

[22]  R. B. Jackson,et al.  Global biodiversity scenarios for the year 2100. , 2000, Science.

[23]  C. Field,et al.  Interactive effects of elevated CO2, N deposition and climate change on extracellular enzyme activity and soil density fractionation in a California annual grassland , 2005 .

[24]  S. Arnott,et al.  THE INFLUENCE OF DROUGHT-INDUCED ACIDIFICATION ON THE RECOVERY OF PLANKTON IN SWAN LAKE (CANADA) , 2001 .

[25]  D. Schindler,et al.  Trophic Dependence of Ecosystem Resistance and Species Compensation in Experimentally Acidified Lake 302S (Canada) , 2003, Ecosystems.

[26]  H. Mooney,et al.  Additive effects of simulated climate changes, elevated CO2, and nitrogen deposition on grassland diversity , 2003, Proceedings of the National Academy of Sciences of the United States of America.

[27]  D. Findlay,et al.  Responses of phytoplankton and epilithon during acidification and early recovery of a lake , 1999 .

[28]  Peter J. Morin,et al.  Environmental warming alters food-web structure and ecosystem function , 1999, Nature.

[29]  Jonathan M. Chase,et al.  Trade‐offs in community ecology: linking spatial scales and species coexistence , 2004 .

[30]  P. Reich,et al.  [Letters to nature] , 1975, Nature.

[31]  W. Keller,et al.  Increased UV-B penetration in a lake owing to drought-induced acidification , 1996, Nature.

[32]  N. Hairston.  The adaptive significance of color polymorphism in two species of Diaptomus (Copepoda)1 , 1979 .

[33]  Stuart N. Lane,et al.  Influence of drought‐induced acidification on the mobility of dissolved organic carbon in peat soils , 2005 .

[34]  H. Blanck.  A Critical Review of Procedures and Approaches Used for Assessing Pollution-Induced Community Tolerance (PICT) in Biotic Communities , 2002 .

[35]  A. J. Tessier.  Comparative Population Regulation of Two Planktonic Cladocera (Holopedium Gibberum and Daphnia Catawba) , 1986 .

[36]  Owen L. Petchey,et al.  Species loss and the structure and functioning of multitrophic aquatic systems , 2004 .

[37]  M. Moore,et al.  Consequences of elevated temperatures for zooplankton assemblages in temperate lakes , 1996 .

[38]  S. West,et al.  Multiple Regression: Testing and Interpreting Interactions. , 1994 .

[39]  D. Schindler,et al.  Consequences of climate warming and lake acidification for UV-B penetration in North American boreal lakes , 1996, Nature.

[40]  D. Findlay,et al.  Climatic influences on algal populations of boreal forest lakes in the Experimental Lakes Area , 2001 .

[41]  Daniel M. Stoebel,et al.  SIZE DOESN'T MATTER: MICROBIAL SELECTION EXPERIMENTS ADDRESS ECOLOGICAL PHENOMENA. , 2003, Ecology.

[42]  W. Steffen,et al.  Global Change and the Earth System: A Planet Under Pressure , 2005 .

[43]  David Raffaelli,et al.  How Extinction Patterns Affect Ecosystems , 2004, Science.

[44]  Patrick L. Brezonik,et al.  Multiple stresses from a single agent: Diverse responses to the experimental acidification of Little Rock Lake, Wisconsin , 1999 .

[45]  D. Schindler,et al.  Effects of Climatic Warming on Lakes of the Central Boreal Forest , 1990, Science.

[46]  C. Williamson,et al.  Ultraviolet and temperature effects on planktonic rotifers and crustaceans in northern temperate lakes , 2005 .

[47]  M. Scheffer,et al.  Impacts of multiple stressors on biodiversity and ecosystem functioning: the role of species co‐tolerance , 2004 .

[48]  D. Mitchell,et al.  Molecular response to climate change: temperature dependence of UV‐induced DNA damage and repair in the freshwater crustacean Daphnia pulicaria , 2004 .

[49]  Marina Manca,et al.  Organisms' response in a chronically polluted lake supports hypothesized link between stress and size , 1998 .