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Aquatic animals protect coastal ecosystems

A new study led by Yale University has found that even small aquatic organisms such as mussels play a crucial – yet often underappreciated – role in protecting and building coastal ecosystems. These animals serve as “ecosystem engineers” – organisms that directly or indirectly drive habitat construction and control the availability of resources for other organisms.

“As sea levels rise, coastal ecosystems have to adapt and evolve to changing conditions,” said study lead author Sinéad Crotty, an expert in Ecosystem Restoration and Environmental Engineering at Yale. “This study shows that small and innocuous animals that live within an ecosystem can play a critical role in helping coastal systems persist in the face of climate change.”

For instance, mussels (Geukensia demissa) help keeping rivers and streams clean by absorbing heavy metals and filtering harmful silt and particulates as they breathe and feed in aquatic ecosystems. Moreover, their shells provide habitat and nesting sites for a variety of insects, small fish, and plants. Finally, through their feeding process, they also deposit large amounts of material on marsh surfaces, thus helping marshes grow through a process called “accretion,” which refers to the natural action of sand, soil, and silt washing up to the land from rivers or the seashore.

The experts designed a series of experiments to examine mussels’ impact on accretion from small, local scales to whole landscape scales, with the largest one involving the relocation of over 200,000 mussels from one landscape to another and measuring changes to the marsh elevation over a period of three years. “We found that, in reality, the effects of mussels are far greater than predicted by the models, and occur at large, landscape scales,” Crotty reported.

Since similar trends are likely to occur with other fauna engineers, such as worms or bioturbating crabs, including these ecosystem engineers in future modeling and ecosystem management is crucial as sea levels continue to rise. 

“This study can help us think through how we prioritize certain marsh areas for protection. Given that mussels are disproportionately important in driving accretion and other ecosystem functions, we should prioritize their protection, or outplanting, as a means to promoting all of their associated benefits,” Crotty concluded.

The study is published in the journal Nature Communications.

By Andrei Ionescu, Staff Writer

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