Novel methods for managing freshwater refuges against climate change in southern Australia. Supporting Document 3: Anthropogenic refuges for freshwater biodiversity
Authors: Edwin T. Chester, Belinda J. Robson and Jane M. Chambers
On the Swan Coastal Plain (SCP) in Western Australia, artificial water bodies are now the most frequently occurring perennial wetlands, and in dry years they may comprise the majority of fresh waters. This study examined the role of artificial urban wetlands (i.e. anthropogenic habitat) as refuges against climate change for freshwater biodiversity. The project undertook a literature review and assessed habitat qualities and species assemblages at over 70 urban waterbodies around the Swan-Canning watershed and SCP. This research showed that artificial urban wetlands are likely already to be acting as refuges on the SCP. In fact, a functional distinction between natural and anthropogenic habitat was difficult to make. Both the sampling and the literature review suggested that waterbodies with beds of aquatic plants, higher dissolved oxygen levels and natural substrata will support the most species. At the landscape level, anthropogenic water bodies that are close to other water bodies or to areas of native vegetation also tended to have higher biodiversity. This research also uncovered evidence that that some species may soon only be viable in perennial anthropogenic waters on the SCP. While it is clear that many freshwater species can survive in human constructed landscapes, it is not yet known whether anthropogenic habitat can function alone as a refuge network, or whether it functions as an adjunct to preserved natural habitat or restored areas. This currently represents the largest single knowledge gap regarding the feasibility of anthropogenic water bodies for facilitating climate change adaptation of freshwater biodiversity. In addition, there is a large amount of unexplained variance in relating habitat variables to invertebrate assemblages, and significant knowledge gaps have also been highlighted by the demonstration of previously unknown survival traits in some of the animals observed in drying experiments, such as the emergence of adult damselflies from drying sediment.