A Reexamination The Freshwater Mussels (Family Unionidae) In Lower Big Walnut Creek

Freshwater mussels (family Unionidae) have become increasingly rare as the threats to water quality, habitat quality, and other aquatic animals, which the mussels depend on, have increased. The absence of mussels can provide evidence that one of these factors is insufficient. Lower Big Walnut Creek (BWC) is known to support a diverse community of mussels but they are unevenly distributed throughout the creek with abundance, density, and richness being high in the upper section, very low in the midsection, and intermediate in the lower section. It has been suggested water quality nor symbiotic fish host communities are responsible for this uneven distribution. The purpose of this study was to understand if mussel communities today are still unevenly distributed, if there are any sign of recovery or change in the distribution, and if we could pinpoint the cause for the midsection decline. This study was done in conjunction with similar studies on the composition and chemistry of the sediments. Mussels were collected using the two phase survey methods of the Ohio Mussel Survey Protocol at nine sites throughout lower BWC. Current trends in mussel communities were analyzed using single factor ANOVA and student t-tests. A Pearson correlation analysis was used to analyze past vs. current trends. We found there is still a significant uneven distribution throughout the creek in abundance (F [2,6] =10.31, p=2.34x10-5), density (F [2,6] = 8.49, p=0.018), and species richness (F [2,6] =6.01, p=0.037), which compare favorably to a past study, with positive correlations in abundance (r=0.68, p=0.043), density (r=0.73, p=0.024), and species richness (r=0.71, p=0.032). However, our study constricted the impacted area upstream and found Truncilla donasiformis (an Ohio threatened species) had increased its range into the creek suggesting recovery is continuing. Sediment analyses are inconclusive at the time.