This article originally appeared in Mongabay.
Described as the “liver of rivers” for their water filtering capabilities, freshwater mussels are facing an extinction crisis. These slow-growing, long-lived bivalves are one of the most threatened groups of animals on the planet. Now researchers in Australia have found that artificial water bodies could provide a lifeline for some species.
Freshwater mussels live in the sediment of streams, rivers and lakes, where they filter water, absorb heavy metals, sequester carbon, and serve as a food source for other animals. But humans have severely modified their habitats with structures including dams, weirs and drains.
The research team wanted to find out if artificial habitats can sustain healthy populations of Carter’s freshwater mussel (Westralunio carteri), a species endemic to southwestern Australia and considered vulnerable to extinction on the IUCN Red List.
The research, published in Pacific Conservation Biology, was motivated by substantial declines in W. carteri over the last 50 years, largely a result of saltwater intrusion and drying habitats. Lead author Jake Daviot of Murdoch University said in a press release that “without proactive and novel approaches to conservation, more populations are going to be lost in the face of human development exacerbated by climate change.”
The researchers surveyed mussels in 12 sites between 2020 and 2024, including six natural habitats and six artificial habitats, such as farm dams and drainage canals. They recorded the size and number of mussels, how spread out they were, and local habitat conditions.
Most of the artificial sites surveyed had a similar density of mussels and clustering pattern compared to natural water bodies. However, population structures varied between the types of sites: artificial water bodies had a higher proportion of large individuals, meaning fewer young mussels. Natural water bodies had higher levels of recent recruitment, the addition of new, young mussels to the population. Continued recruitment is important to sustain populations in the long term.
Freshwater mussels are parasitic, relying on host fish to disperse their tiny larvae, which drop into the sediment, then live sedentary lives. Host fish are one way mussels can colonize artificial water bodies and are important for continued recruitment.
Nathan Johnson, a research biologist at the U.S. Geological Survey, who wasn’t involved with the study, told Mongabay by email that freshwater mussel species that are highly specialized for either host fish or habitat tend to struggle in artificial habitats. However, mussels that rely on a broader range of host fish “often show greater adaptability, often surviving or sometimes thriving in artificial or degraded habitats.” That makes species-specific research on the value of artificial habitats important for effective management, he said.
“Our natural habitats are irreplaceable, but artificial waterbodies can buy these mussels precious time,” Daviot said. “Artificial habitats can act as ‘arks’, safeguarding populations until our rivers recover.”