Mussels are disappearing from the Thames and growing smaller- and it’s partly because the river is cleaner

Getting our water sources cleaner has long been the ultimate goal, but have we thought of potential negative outcomes? Bodies of waters house significant diversities of species that different from country to country. We do not even know yet all the species that live beneath the surface. One group of organisms are bivalves, which are categorized as filter feeders. These filter feeders survive by syphoning particles and planktons from the water columns in both freshwater and saltwater. They are known to help keep aquariums clean and essential members of the clean-up crews. One of these essential species is the freshwater mussel.

Several of the freshwater mussel species found in the Thames – the painter’s mussel, the swollen river mussel, and the duck mussel.Author provided

Since they are stationery and burrow into riverbeds, the mussel is used as an indicator of the health of the river in which they live within. They keep the river’s water clean and help prevent the development of potentially harmful algae blooms. Recently, the populations of freshwater mussels found in the Thames River have been evaluated compared to a 1964 study. The results showed that the population of freshwater mussels have declined by 95% and their size/growth rates have decreased by 10%-35% since 1964. Researchers found two potential causes for these decreases: the introduction of the invasive zebra mussel and the river becoming cleaner. The Thames have long been heavily polluted but after a lot of hard work it is now ranked one of the cleanest urban rivers globally. Lower levels of nutrients in the river means less food for the mussels, which may be why they are smaller and slower to grow. Cleaner rivers is a great achievement but now we must figure out how to preserve such an important part of the ecosystem. To learn more about this please see The Conversation’s article https://theconversation.com/mussels-are-disappearing-from-the-thames-and-growing-smaller-and-its-partly-because-the-river-is-cleaner-195402