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Lake County forest staff finds rare aquatic species
A Mississippi grass shrimp found in the Des Plaines River near Libertyville in Lake County. The species is unusual to the area and indicates improved water quality. | Photo courtesy of the Lake County Forest Preserve
Updated: February 19, 2013 1:58PM
After almost 20 years with the Lake County Forest Preserve District, it takes a pretty unusual find to wow Natural Resource Manager Jim Anderson.
But a tiny crustacean, measuring just one-inch in length, stopped Anderson in his tracks during winter identification in late January.
“Wow, I haven’t seen these since back in the early ‘80s,” Anderson recalled saying. “That’s a freshwater shrimp — a Mississippi grass shrimp.”
Anderson hadn’t seen a fresh-water shrimp since his undergraduate days in Carbondale, where he studied streams and aquatic invertebrates. The positive identification of Palaimonetes Kadikensis in the Des Plaines River in southern Lake County is big news for ecologists and conservationists.
This is the first documented occurrence of this species in the county, Anderson said. While the shrimp are indigenous to the area, Anderson speculates they probably have been unable to survive here since the 1800s.
“Fresh-water shrimp is a species that’s pretty sensitive to poor water quality. Finding it in the Des Plaines River is an indication that the quality of water in the Des Plaines River is improving,” he said.
When the forest preserve’s natural resource crew snagged a dozen or so of the translucent specimens with nets last summer during their annual sampling process, they realized the critters that scurried across the river bottom like a crayfish were some sort of crustacean. But they didn’t know until this winter, when Anderson could finally put a name to what, exactly, they had found.
The find is rare for northeastern Illinois, as Mississippi grass shrimp can’t survive in sediment in the water and need healthy vegetation to survive. The only other known area locations are in the Kankakee River and Otter Creek in Kane County.
“They’re much more abundant in the Kankakee River system, which is a high-quality river,” Anderson said.
The forest preserve alerted the Illinois Natural History Survey and the U.S. Army Corps of Engineers to its find.
Lawrence Page, of the Illinois Natural History Survey, said the Mississippi grass shrimp “almost always is associated with, and is most abundant in, living aquatic vegetation.”
The Army Corps will add the Lake County find to a crustacean species database the organization is creating, Anderson said.
Besides looking for more shrimp this summer, the forest preserve crew will expand its focus.
“We’re going to try to look at mussels and clams that are there,” Anderson said. “They’re difficult to collect and difficult to identify.”
No matter what else they uncover, Anderson expects the Mississippi grass shrimp will always hold a position of prominence.
“This is kind of an important one,” he said.
