Scientists Tested Freshwater Mussels From the Thames River- Raised Concerns About Ecosystem’s Survival
From tiny trickles of springs downsloping along the hillsides of a remote village meadow to a 215-mile-long stretch of water, the River Thames holds the status of the longest river in England and the second longest in the UK. After all those years of climate change, the river now squooshes with a mush of silt, soil, and sediment that contributes a muddy brown hue to its water.
In between the portions where arrays of wildflowers like bladderwort, woody nightshade, Himalayan balsam, hollyhock, willowherb and brown knapweed fringe the borders of its turbid and brackish water streams, prowls a bounty of wildlife, including seals, porpoise, sea horses, leafy sea dragons, starry smoothhound sharks, and other aquatic creatures, not to forget the mussels. A new study published in the journal Animal Ecology revealed that the current population of mussels is just 5% of what it was six decades ago.
Mussels, the wedge or pear-shaped creatures are known to be highly significant for an aquatic ecosystem. They not only filter out silt and sediment from the water but also enable habitats that cradle a variety of insects and underwater organisms. Using their sticky “beards,” they latch their bodies onto surfaces like rocks, clinging there for as long as they survive. Their bodies are dotted with tendril-like threads, whose tips are sopped in sticky underwater glue or adhesive plaques, with which they release proteins into the rocky surfaces and trap all the water molecules lingering there. Over time, they reproduce and form vast beds and gummy carpets along the river’s edges.
A good mussel population, therefore, is regarded as an indicator of the ecosystem’s health. So when a team of researchers from the University of Cambridge replicated a 1954 study to measure the size and number of mussel species, they came across an alarming revelation. They found that the population of mussels decreased by a dramatic decline of 95%, including that of duck mussels which decreased by 1.1 percent and painter’s mussels which fell by 3.2 percent. “This dramatic decline in native mussel populations is very worrying, and we’re not sure what’s driving it,” said lead author and Professor David Aldridge from the University of Cambridge, in a university press release.
“While this might seem like a rather parochial little study of a single site in a single river in the UK, it actually provides an important warning signal about the world’s freshwaters,” he added. One possible cause behind this declining number could be the invasive species called zebra mussels. But they aren’t so sure about it. Even natural factors could have prompted this change. For instance, the decreasing levels of mussels’ primary food sources, nitrate and phosphate, could be the root cause of the declining mussel population. These elements are already on the verge of declining due to stricter sewage regulations.
“Mussels are a great indicator of the health of the river ecosystem. Such a massive decline in mussel biomass in the river is also likely to have a knock-on effect for other species, reducing the overall biodiversity,” Isobel Ollard, first study author and a PhD student at the University of Cambridge said in the press release. “The depressed river mussel used to be quite widespread in the Thames, but this survey didn’t find a single one - which also raises concerns for the survival of this species,” she added.