Mitigating impacts of climate change on stream food webs
Authors: Ross Thompson, John Beardall, Jason Beringer, Mike Grace and Paula Sardina
Restoring riparian vegetation in temperate south-eastern Australian freshwater habitats is an effective adaptation to changes in climate. Studies of streams revealed that the presence of riparian vegetation can help to cool stream temperatures, as well as well as maintain higher diversity and abundance in stream invertebrate communities. These temperature-regulating benefits of riparian vegetation will be of particular importance to mayfly species and the ecosystems they support. When stream communities were exposed experimentally to increased temperatures, the emerging adults of all aquatic insect species were impacted and responded in species- and sex-specific ways. Most concerning of all was the impact on male mayflies under the 2100 climate change scenario. They emerged faster under 2100 temps compared to 1990-2000 temps, implying a change in the sex ratio that could potentially compromise populations and ultimately lead to local extinctions. Within the aquatic invertebrate communities, there was an observed change in size structure, with a shift from bigger to smaller species. This change is in accord with the ecological rules dealing with the temperature-size relationship. Changes in basal processes (algal productivity, carbon dynamics) were also monitored during the experiment, but these processes appeared to be relatively resistant to the climate change scenarios predicted.