Mussels on Sycamore’s Preserves

By Cassie Hauswald, former Indiana Freshwater Ecologist at The Nature Conservancy in Indiana

While monitoring a remote property in Green County, Sycamore Land Trust’s Land Stewardship Director Chris Fox found two species of mussel shells on a hike through Clifty Creek. Mussels have a fascinating and odd life cycle and are very important to the health of our ecosystem. They act as natural filters and are indicators of good water quality and habitat stability. Yet despite their importance to the health of the land, most are imperiled. To determine these species of the mussels he found, Chris checked with Cassie Hauswald, formerly Indiana Freshwater Ecologist at The Nature Conservancy in Indiana, who is an expert on freshwater mussels. Cassie is now with the Sam Shine Foundation.

Rainbow mussel

Threeridge mussel

December can provide those rare balmy days when water levels are low to check in on what is living below the water surface.  Finding mussel shells is one way to assess what species live in Indiana streams since living mussels typically bury themselves in the stream substrate and are not so easy to detect – part of the reason for their persistence in smaller streams like Clifty Creek.  The shells Chris was finding were not weathered dead, but represented species that had recently deceased, most likely from age or being foraged for an otter’s dinner.

Two species of interest were noted.  The threeridge mussel is a common species in Indiana streams and depends upon fish such as rock bass and bluegill to complete their lifecycle.  The other mussel shell that Chris discovered was an older rainbow mussel.  He knew it was older because this is a fairly small mussel and the shell he found was maxed out in terms of size and hence age.  Rainbow mussels are not uncommon in Clifty Creek, but they are gone from many Indiana streams.  The rainbow is a species of special concern in Indiana.  

Freshwater mussels are an indicator of long term trends in water quality because they gather their food by filtering the water around them for algae and bacteria.  Excess soil and sediment in a river, stream or lake can choke out mussels, but the sediment is likely a proxy for other contaminants that come from how humans use the land.  Freshwater mussels congregate in beds or shoals of rivers where the stream bottom is stable and unaffected by scouring and channelization.  As a general rule, the streams and rivers where mussels are still found in Indiana represent areas of better water quality and less human impact.  They also tend to be in rivers and streams where humans want to be; fishing, swimming or canoeing.  SLT’s preserve is one such place along Clifty Creek in Greene County. 

Because they are sedentary creatures, freshwater mussels bloom where they are planted.  They arrive at new locations within a river system because they are parasites on fish in their juvenile stage of life and each mussel has a specific fish or group of fish that it attracts to raise its young.  Mussels employ a variety of lures and odors to entice specific fish to their larvae.  Streams with dams block the movement of fish and can thus limit the distribution of freshwater mussels.  Clifty Creek is part of the Wabash River basin; following Clifty Creek downstream it flows into Plummer Creek, which flows into Richland Creek on to the West Fork White River and eventually the Wabash.  The Wabash River is the largest free-flowing section of stream east of the Mississippi River with no dams on the Wabash from Huntington, Indiana to its confluence with the Ohio River.  The connection between SLT’s preserve on Clifty Creek and the Wabash River, with few obstacles in between to fishes, means our land protection is not only providing for cleaner water in Clifty Creek, but also boasts freshwater mussels.

Remember, mussel shells are protected in Indiana, meaning you must possess a permit to keep the shells. Just as Chris was using the mussel shells as a record of what occurs in the stream, leaving the shells assures that future generations can understand the history of our streams, not to mention the habitat the shells provide to other fish and invertebrates that call Clifty Creek home.


Thanks Cassie for sharing her mussel wisdom! Sycamore’s work benefits from many partnerships like this one with The Nature Conservancy that help us identify and better understand how to protect the species we find on our nature preserves. It takes a village to protect and care for southern Indiana’s natural treasures, and we are grateful for ours!