Mussels as water cleaning ‘ecosystem engineers’


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Mussels play helpful roles in river ecosystems (via Creative Commons). 

Julia Poska | March 12, 2020

A group of citizens in Muscatine, Iowa are pushing to restore the over harvested Mississippi River mussel population. The “Mussels of Muscatine” group hopes to create learning opportunities, reverse damage to the river ecosystem and improve water quality.

The group wants to convert a dilapidated pump house into a mussel research and propagation facility, according to the Des Moines RegisterThat plan faces several logistical hurdles, but the idea that mussels could help reverse some of Iowa’s water quality degradation is valid.

CGRER member Craig Just, a University of Iowa associate professor of environmental engineering described mussel’s role as ‘ecosystem engineers’ to the Register. As the molluscs filter nutrients from the water to feed, they remove pollutants like nitrogen. Just said mussels can also remove microorganisms like algae and phytoplankton, which are harmful to ecosystems when their populations explode.

Just pointed to several challenges to restoring the Mississippi mussels as well. Iowa soil erodes into waterways at high rates, which would bury mussels and prevent them from reproducing. Mussels also must eject their larvae into fish gills, a difficult process to recreate in a lab or propagation facility.

Endangered mussel may be making a comeback in the Iowa River


The Higgins' eye pearlymussel, an endangered species which was found in the Iowa River during this year's Mussel Blitz. (USFWSmidwest/Flickr)
The Higgins’ eye pearlymussel, an endangered species which was found in the Iowa River during this year’s Mussel Blitz. (USFWSmidwest/Flickr)

After a week of scouring along the Iowa River, researchers and volunteers from the Iowa Department of Natural Resources made promising findings regarding Iowa River’s mussel population, a critical indicator of the waterway’s aquatic health.

The experts found 20 different species during the 2014 Mussel Blitz, an annual research project to assess the health and diversity of Iowa’s mussels. Among them was the Higgins’ eye pearlymussel, an endangered species which was reintroduced to the river in 2003 by stocking fish with young specimens, at the time just the size of a grain of salt. Researchers found six adult Higgins’ eyes in the Iowa River during the Mussel Blitz, indicating that the species was able to mature in the waterway.

While mussels thrived in Iowa waterways for centuries, most have faced heavy setbacks due to damming, fluctuations in water levels and chemicals in the water. 43% of North America’s 300 mussel species are in danger of extinction, including 78 endangered or threatened species in the Midwest.

Since their primary threats are sedimentation and pollutants, mussels are important to Iowa’s waterways as indicators of aquatic health. Reproducing populations of mussels indicate good water quality and wildlife diversity, and mussels help purify the aquatic system by acting as natural filters. They’re also an important food source for otters, herons and some fish.

Bridge construction will continue without mussel survey


Photo by Niall Crotty; Flickr
Photo by Niall Crotty; Flickr

When officials in Quasqueton proposed a new bridge over the Wapsipinicon River, they were required to survey and relocate the local mussel population before construction could begin. However, due to consistently high water levels, the survey has yet to be conducted, and has now been delayed until until after the bridge is built. Continue reading