Native freshwater fish diversity in the Murray-Darling Basin could be under serious threat from climate change in coming decades, a new study has found. This loss of biodiversity could result in a further decline in the health of the Basin.
The study, which has been published in PLOS ONE, was co-led by Griffith University researcher Associate Professor Mark Kennard from the Australian Rivers Institute and visiting Brazilian PhD student Anielly Oliveira.
Also involved were Brazilian collaborators from the State University of Maringa, the Federal University of Goias and the Federal University of Technology Parana, as well as Australian collaborators from La Trobe University and the NSW Department of Fisheries.
“Freshwater fishes are highly valued for commercial and recreational fishing and for their cultural and intrinsic importance, and they also have a critical role in maintaining healthy ecosystems,” Professor Kennard said.
“For these reasons, we wanted to understand how fish biodiversity in the Murray-Darling Basin may change in response to a projected warmer and dryer future climate.”
The study combined species distribution modelling with information about the functional traits of fish to predict the impacts of climate change on native fish biodiversity.
“The effect of environmental changes on species distributions is partly determined by the functional traits of the species,” Professor Kennard said. “Traits are characteristics of a species that are linked with fitness and performance such as morphology, physiology, life-history and behavior.
“That’s important because changes in the functional composition of fish communities can have significant effects on ecosystem structure and resilience.”
The research team modelled future changes in taxonomic and functional diversity in 2050 and 2080 for two scenarios of carbon emissions. The predictions were then used to identify priority areas for conservation management of freshwater fish in the Basin.
“We concluded that either scenario could result in major contraction of species ranges,” Professor Kennard said. “That could lead to a severe, negative effect on both the distribution and functional traits of fish communities within the Basin.”
The predictions showed losses of climatically suitable areas, species and functional characters in parts of the northern and western Murray-Darling Basin. They also identified future climatic refuges for fish fauna in the southern portion of the basin, in the upper Murray River catchment.
“This work provides new and important information for conservation efforts and climate adaptation initiatives in the Murray-Darling Basin,” Professor Kennard said.
“For example, this could include enhancing current efforts by catchment managers to mitigate other threats like river fragmentation, flow alteration, water pollution, riparian zone degradation and aquatic invasive species.
“We hope this work will be valuable for policy makers and catchment managers as we all strive to conserve the unique native fish biodiversity of one of Australia’s most important and iconic rivers.”
‘Coupling environment and physiology to predict effects of climate change on the taxonomic and functional diversity of fish assemblages in the Murray-Darling Basin, Australia’ has been published in PLOS ONE.
This work was supported by the Australian Rivers Institute, Griffith University, and the Brazilian Conselho Nacionalde Desenvolvimento Cientifico e Technologico (CNPq) and Coordenacao de Aperfeicoamento Pessoal de Nıvel Superior (CAPES – PROEX) Ph.D. scholarship and travel fellowship.