Means and extremes in climate-impacted freshwater ecosystems: an experimental approach

SARDIÑA PAULA; BEARDALL JOHN; BERINGER JASON; GRACE MICHAEL; THOMPSON ROSS

Melbourne

Congreso; Ecological Society of Australia - 2012 Annual Conference; 2012

Ecological Society of Australia

Background/Question/Methods: Predicting the effects of climate change on freshwater ecosystems remains challenging despite a growing number of empirical and experimental studies. Empirical studies have generally emphasised increases in mean temperatures, when many parts of the world will be impacted by changes in frequency of climatic extremes. Here we sought to understand how realistic weather scenarios generated from regional climate models might impact aquatic food webs in south eastern Australia. Using temperature controlled flumes we subjected river food webs to weather scenarios based on 2070 climates and measured a range of factors including algal responses, changes in invertebrate communities and measures of ecosystem function. Results/Conclusions: Food webs exposed to the climate change scenarios showed distinct responses. In particular, there were changes in invertebrate communities, driven in part by species-specific responses of warming. The dominant mayfly in the community responded to the future climate scenario by emerging at a smaller size, and by alterations in sex ratios. Other taxa showed no response. Changes in algal communities were evident, but tended to be highly variable between replicates. These results show the altered community and food web structure in aquatic systems affected by climate change, and the potential for species-specific responses to be important drivers in community-level responses.