When most people think of the quagga mussels, they picture its devastating impact on infrastructure. When these highly invasive mussels were first discovered in Idaho, state officials issued a stark warning: if quaggas became established in the Snake River, it could cost the state hundreds of millions of dollars. The primary concern? The potential for quaggas to seriously clog up the many water diversion structures, intake pipes, and hydroelectric dams on the heavily developed Mid-Snake River corridor.
While quagga mussels’ impacts to infrastructure can be immense, the wholesale disruption quaggas cause to aquatic ecosystems has the potential to be just as devastating. Given that the Idaho State Department of Agriculture is still fighting to eradicate quaggas from the Mid-Snake River in southern Idaho, it is a timely moment to summarize the serious ecological consequences quaggas could have on our precious lakes, rivers, and streams if they ever were to become established here in Idaho (something we all hope never happens!).
1. Disrupting food webs and crowding out native species
Quaggas are relentless filter feeders. Collectively, they consume massive amounts of plankton, which in turn deprives many native aquatic organisms (e.g. small fish and invertebrates) of a key food source at the base of the food web. Quaggas also form dense colonies that crowd out native species, reduce local biodiversity, and affect fish spawning. For instance, fish may not have access to their usual spawning areas on underwater rocks if those surfaces are blanketed by quaggas.
2. Improving water clarity–but at a cost
While quaggas can actually improve water clarity as they filter large volumes of water, this actually has negative effects on the aquatic ecosystem. Clearer water allows sunlight to penetrate deeper into a lake or river, which can stimulate the growth of nuisance aquatic plants at greater depths. This shift can disrupt the balance of plant species, impacting the organisms that depend on those plants for food and disrupting the overall ecosystem.
3. Worsening toxic algae problems
Quagga mussels are selective feeders, often avoiding toxic algae that may be present in the water while disproportionately feeding on the non-toxic variety. As a result, the concentration of toxic algae in the water increases, which can cause or worsen outbreaks that threaten human health along with pets and livestock.
4. Bioaccumulation of pollutants up the food chain
Because quagga mussels filter water so effectively, they can accumulate pollutants like heavy metals in their tissues at alarming rates—sometimes up to 300,000 times the concentrations found in the surrounding water. When predators higher up the food chain (such as fish, birds, and even humans) consume these mussels, the pollutants enter their bodies as well, potentially contaminating fish and shellfish, as well as people that rely on them for food.
As you can see, the ecological consequences of a quagga mussel infestation would be immense, especially if they ever got into more sensitive aquatic ecosystems like the Salmon River (for example). Thus, the best thing we can do to avoid these ecological impacts is to prevent the spread of quagga mussels in the first place.
If you’re a boater, it’s crucial to follow the Clean, Drain, Dry protocol every time you use your boat to help stop the spread of these invasive mussels. For our part, we will continue advocating for stronger invasive species prevention efforts in Idaho, including additional boat check stations and decontamination facilities across the state.
Together, we can protect Idaho’s aquatic ecosystems from the threat of quagga mussels.