By Dr Simon Linke
The importance of the world’s freshwater systems as providers of biodiversity and other ecosystem services is undisputed. At the same time, freshwater systems are also among the world’s most threatened systems, with 65% of river systems moderately to highly threatened and extinction risks being significantly higher than in terrestrial systems. This is not good!
We need to better protect freshwater ecosystems and the threatened animals living in these environments. But two main reasons make it difficult to protect threatened species in freshwater systems.
- Monitoring of threatened critters is a lot more difficult in freshwaters than in terrestrial systems. Trends in rare birds or declining mammals like koalas can be detected by citizen scientists who survey their habitats, whereas underwater dwellers can only be detected by targeted surveys.
- Streams and rivers constantly move, and it is thus difficult to ‘protect’ endangered species or ecosystems using more traditional approaches, such as national parks. Protecting critical habitats for spawning fish or endangered frogs is not enough if human activities, such as mining or agriculture are undertaken upstream, in the rivers headwaters.
The Australian Rivers Institute is currently aiding progress towards both of these questions.
Novel methods that make it easier to detect species in decline include new methods in audio and video monitoring. For example, we are currently working on the cutting edge of underwater acoustics. Up to 20% of fish make noises, as do major groups of aquatic insects. A nightly chorus of freshwater bugs and beetles can remarkably sound like a forest.
We are leading a charge in cataloguing underwater sounds, which are currently underrepresented in global sound archives that house millions of bird calls. This can be achieved by combining underwater audio and video, like in this example of two spangled grunters talking to one of our microphones. Our PhD student Emilia Decker is also researching the links between sounds and river health.
Dr Simon Linke recording with hydrophones on the Mary River (Image: Leah Barclay)
Once we know where threatened species live, we can plan to better conserve them. And freshwater ecosystems need a lot more conserving. Under the 2010 Convention on Biological Diversity (CBD), the international community had signed up to protect 17% of all ecosystems. Two studies by our researchers discovered that globally both rivers and wetlands fall short of this target.
This is especially true the world’s largest rivers, including the Mississippi, the Volga (in Russia) or the Murray-Darling are well below the 10% mark, calling for expansion of river protection globally. ARI PhD student Vanessa Reis also found that only 11% of the world’s wetlands were protected. Particularly high human influence was found in Asia, which contains the largest wetland area of the world and where wetlands are intensively used for food production and land reclamation.
For more information on how listening to rivers can improve biological diversity, please visit our Biosphere Soundscapes webpage.
A multi-scale assessment of the global wetland conservation