Recently, from July 20th to the 23rd, MWA conducted freshwater mussel surveys with assistance from Western Pennsylvania Conservancy (WPC). DCNR staff members from Ohiopyle and Laurel Hill State Park were also able to participate in our study and were incredibly helpful. These surveys took place in the Indian Creek, Laurel Hill Creek, and Middle Youghiogheny River watersheds. Ultimately, our goal was to identify the possible presence of native freshwater mussel populations and assess if we could find any suitable habitat. Although us here at MWA do not typically collect this kind of data, the team from WPC are freshwater mussel pros and conduct similar surveys multiple times a year.
Overall, the Mountain Watershed Association wanted to conduct this survey for a few reasons. First of all, mussels are great filters! We want to know if they are in our waterways because they are able to naturally filter bacteria, algae, pollutants, and detritus. In addition to this, they are both indicator and keystone species (Knowles, n.d). Being a keystone species means they play a large role in their ecosystem. For example, they have a huge positive impact on water quality, are a sought-after prey, and increase the diversity of habitat in an area (Center for Biological Diversity, n.d) On the other hand, being an indicator species means that their presence in a system can provide us with valuable ecological insight. When present, we are able to more easily conclude that an area is healthy. Likewise, a decreasing mussel population size indicates that there likely is a negative impact influencing their overall environment (Knowles, n.d).
We began our field work in the Indian Creek Reservoir below the dam. This site was packed full of clam shells (picture 2). However, these are not native mussels; they are an invasive Asiatic species known as Corbicula. WPC commented that not many people know this species is invasive and that they often receive false leads because of it. Unfortunately, from here on out Corbicula was found in every site we visited. A member of WPC informed us that it is speculated that these clams may be out competing native mussels. But it is important to note that this idea is still up for debate in the ecological community.
Over the course of our three-day excursion, we largely did not find evidence of any thriving freshwater mussel populations in any of our systems. Despite our largely unfruitful search, at our very last spot we did find three deceased shells of cylindrical papershell mussels (Anodontoides ferussacianus). WPC’s zoologist, Ryan Miller, was able to provide us with a little bit of information about these samples. He explained that the individuals we found were probably unintentionally transported to the system from the gills of a stocked fish. A theory is they (the mussels themselves or an inoculated host fish) also could have been washed out of a local pond or from Laurel Hill Lake and settled into that slow moving stretch of Laurel Hill Creek for a few years. Miller then speculated that these mussels most likely lived out the remainder of their lives for a few years but were unable to establish any subsequential generations.
Although our study did not produce the high population numbers we were hoping for, we still walked away with valuable data! WPC indicated that several of our sites, even though they lack mussels, have very suitable mussel habitat. With this in mind, it is possible that our area may have once had a thriving mussel population. This idea is further supported with local stories that mussels were historically found in the area. However, it is widely understood that a large majority of our waterways were horrifically polluted by acid mine drainage to the point where little to no aquatic life was viable. Any population that we may have had could have been completely killed off because of this.
MWA is devoted to doing all we can do to protect and improve water quality in the greater Youghiogheny River watershed. Now that we know that we do not have active mussel populations in the area, we can begin to take our next steps. We are still waiting on WPC’s official report from this survey, but in the future, if historic and scientific data support it, we might consider transplanting preexisting populations to our waterways. This is something we are interested in doing because, without intervention, it could take decades for native species to reestablish. This would be a huge project for MWA to take on, but we are willing to do whatever it takes to make our waterways as healthy as possible!
Knowles, S. (n.d). Native Freshwater Mussel Health. USGS. Retrieved August 4, 2021, from: https://www.usgs.gov/centers/nwhc/science/native-freshwater-mussel-health?qt-science_center_objects=0#qt-science_center_objects
Center for Biological Diversity. (n.d). Freshwater Mussels. Retrieved August 4, 2021, from: https://www.biologicaldiversity.org/campaigns/freshwater_mussels/