Measuring Local Dewatering Of Freshwater Mussels In the Yamhill Watershed

My research focused on freshwater mussels in the Yamhill Watershed. The research team I was a part of was focused on determining how extreme the changes in water depth and velocity experienced by mussels are, specifically under increasingly prevalent low-discharge conditions. We censused mussels and measured environmental variables including depth and velocity. We then compared those variables from the beginning to end of summer to see how dramatically they had changed. One of the most striking differences here is the increase in mussels at the surface level in July versus August. Surface was defined as 5cm or less. The bottom graph shows the overall change in mussel depth beween the two months, which came out to be a decrease from 25.5cm to 17.8cm. The graphs on the right depict the changes in water velocity experienced by mussels between July and August. The number of mussels in stagnant water increased greatly, and the number of mussels in flowing water dropped to almost zero. The bottom graph then shows the average water velocity experienced each month, highlighting the decrease from 7.6m/s to 0.8m/s. Both of these results ended up baring significance as proved by the Wilcoxon Rank Sum tests ran. This test is for comparing the mean of two groups, hence why it was suitable for this research.