DNR confirms zebra mussels at Lake Manawa

by | Jul 29, 2020 | 5 Ag Stories, News

An aquatic invasive species known to negatively impact ecosystems has been discovered at Lake Manawa in Council Bluffs.

According to the Iowa DNR, zebra mussels were recently confirmed in the waters of Lake Manawa. Investigation by DNR staff discovered low numbers of zebra mussels around the lake, according to aquatic invasive species program coordinator Kim Bogenshutz.

?Luckily, a lake shore owner found them and alerted us that they found some zebra mussels,? Bogenshutz said. ?Some staff and I went over there and checked it out. We did find, not many, but individual zebra mussels all in different locations around the lake. Unfortunately, there is a population there in Lake Manawa.?

Zebra mussels look like small, D-shaped clams that have alternating light and dark bands. Most are less than one inch long. They are filter feeders that can form dense clusters as they attach to hard underwater surfaces. Bogenshutz says large infestations of zebra mussels can cause problems.

?When there gets to be millions of them in the lake, they filter out a lot of the food that the native mussels and fish need,? Bogenshutz said. ?What people will physically see is that zebra mussels have little what we call thistle threads on them. They attach to hard structures like rocks, docks, boats, and pipes. They clog up a lot of things and cause a lot of problems, and their shells are sharp.?

Bogenshutz believes the zebra mussels in Lake Manawa arrived either on or in a boat that had picked them up from an infested water body, such as the nearby Missouri River. Currently, there is not effective treatment to control zebra mussels once they have infested a lake.

?Once zebra mussels are here, there is nothing that will kill them that doesn?t impact our native mussels,? she said. ?Right now, once they?re here, they are here. Preventing their spread is the way we are trying to control them.?

For more information about aquatic invasive species and a list of infested waters in Iowa, visit iowadnr.gov.