PS 60-31
Freshwater mussel community structure in a northeastern Ohio watershed
Background/Question/Methods
Agricultural development can lead to a number of stream impairments, including sedimentation and increased flood frequency and intensity. These processes have a negative impact on the freshwater mussel community, especially in the larval and juvenile stages. Many populations persist in North American streams, but are composed of larger individuals with low recruitment. Eagle Creek, located in Portage and Trumbull counties, Ohio, is located in a mixed agricultural and forested watershed. Most sites were impacted to some degree, ranging from a forested nature preserve to agricultural fields along the bank. Between May and August, 2013, surveys were conducted for freshwater mussels (Unionidae) in Eagle Creek at eight sites between Garrettsville, OH, and the confluence with the Mahoning River. Visual surveys were used to locate mussels in most areas, as was permitted by the shallow water. Tactile searches and mussel rakes were also used to survey deeper areas and to find smaller mussels. Mussels were removed from the sediment and collected for identification of species, measurement of maximum length, and estimation of age by counting growth lines when possible.
Results/Conclusions
Many live mussels were found in Eagle Creek (n=673), consisting of eight species. All sites were dominated by the fatmucket (Lampsilis siliquoidea), which comprised 73% of live mussels. One-way ANOVA showed significant differences in length and estimated age between some of the sites. The largest and oldest L. siliquoidea were found at the furthest upstream site, which is located approximately 0.5 miles downstream of a dam in Garrettsville. This may be a result of reduced recruitment of juvenile mussels from upstream. However, there were no consistent patterns in size and age distribution, diversity, or abundance along the remainder of the stream. Few young mussels (<5cm) were found, indicating possible lack of recruitment, although the survey methods may not be adequate to detect them. It appears that Eagle Creek may have recently experienced increased disturbances that have caused the mussel populations to slow or stop growth. This is an indication of a possible extinction debt for mussels in this stream. Future studies will investigate the land-use and hydrologic variables that may influence diversity, abundance, size, and age of freshwater mussels throughout the entire Upper Mahoning River watershed.