Freshwater Mussel Extinction

According to the U.S. Fish and Wildlife Service, The Endangered Species Act was created in 1973 to “establish protections for fish, wildlife, and plants that are listed as threatened or endangered.”

When we think about endangered species, we envision high-profile mammals that are impressive and majestic: the American bison stampeding across the plains of the U.S. west: the African elephant roaming the savanna: or the Bengal tiger resting in the shade in a national park in India. The long list of animal species threatened with extinction includes creatures big and small, and unfortunately it is typically only the larger majestic animals that get press coverage. But there are countless species of creatures, a fraction of the size of these mammals, that exist in all corners of the earth and struggling to avoid extinction, out of sight and as a result typically out of mind. One such creature, living in obscurity in the murky depths of our bodies of water, is the freshwater mussel.

Does it matter?  

Populations of freshwater mussels have been decimated around the globe, with dozens of species already extinct or rapidly facing extinction. Assaulted by population growth and human overdevelopment – and the subsequent habitat loss – the freshwater mussel has suffered from the proliferation of damns and extensive water pollution in our rivers, lakes and streams.

While the plight of freshwater mussels might elicit a “does it really matter?” type of cursory response, it doesn’t take much digging into the issues to reveal a much more complex answer. As is the case with most bivalve mollusks (clams; oysters; scallops), freshwater mussels provide critical benefits for their environment. Whether it’s filtering out pollutants, stabilizing river and stream beds, or providing crucial habitat for other underwater creatures, freshwater mussels play a much more important role in their ecosystems than their modest physical size might suggest. Since freshwater mussels continuously filter the water around them, they are an important bellwether for the condition of an ecosystem and provide key insights about the overall health of that ecosystem. With dozens of species of freshwater mussels already extinct, the scientific community is scrambling for answers to determine root causes and to make any attempts to stop the trend.

Freshwater mussels and nutrient pollution

Naturally occurring nutrients (primarily nitrogen and phosphorus) at normal levels in oceans, lakes, rivers and other bodies of water are healthy, as they support the growth of algae and aquatic plants. These algae and plants in turn provide food and habitat for fish, shellfish, and smaller organisms that live in the water. Freshwater mussels are a continuous filtering mechanism of the water in their environment, but too much nitrogen and phosphorus can be toxic to the mussels – and to all organisms – creating what is referred to as nutrient pollution.

Why is nutrient pollution a problem?

Nutrient pollution, created by excessive levels of nitrogen and phosphorus in bodies of water, typically originates from industrial fertilizer or waste runoff from factory farming, industrial facilities, or wastewater treatment plants. These increased levels of nutrients can deteriorate water quality, as algae can grow rapidly, reducing or even eliminating the oxygen supply and reducing the exposure to sunlight. Freshwater mussels can’t keep up with the overabundance of these nutrients, so the water quality in the ecosystem continues to suffer.

Nutrient pollution has been exacerbated by climate change, with increased water temperatures (more conducive to algae growth) and bigger storms (heavier rainfall leading to increased erosion leading to a greater influx of nutrients from the runoff). Nutrient pollution leads to habitat damage, loss of aquatic life, drinking water contaminated with toxins and bacteria, and ultimately negative impacts on human health. According to the New York State (U.S.) Department of Health, contact with contaminated surface waters can cause diarrhea, nausea, or vomiting; skin, eye, or throat irritation; and allergic reactions or breathing difficulties.

As much as wastewater treatment plants have been identified as a critical solution for implementing technologies aimed at addressing nutrient pollution, it is an all-too-common occurrence in communities around the U.S. and around the globe. It is estimated that the cost of treating and preventing nutrient pollution – in the U.S. alone, between the years 2010 and 2020 – cost more than $1 billion, and that figure is expected to rise as global temperatures rise. Nutrient pollution will continue to wreak havoc on our freshwater mussels and on our water supplies. From our biggest oceans to our smallest rivers and streams, we need to take a serious look at the use of industrial fertilizers and agricultural runoff – and begin to make changes – as if our world depends on it.

All is not lost

News about environmental issues around the globe – such as the extinction of freshwater mussels – can be upsetting and even unnerving. But there are seeds of hope being planted to help address climate change in our world. Students at Middlebury College in Vermont, U.S., have developed a plan to restore freshwater mussels in the Connecticut River, with support from the Connecticut River Conservancy and other local nonprofit organizations. Part of their plan is to also help increase awareness of freshwater mussels, and the important role they play in freshwater ecosystems. It is efforts like this, and others like it, that will help to turn the tide when it comes to nutrient pollution and the preservation of small, seemingly “insignificant” animal species like the freshwater mussel.