Native mollusk species including the California floater (Anodonta californiensis), the western ridged (Gonidea angulate), and the western pearlshell (Margaritifera falcate) have seen range reductions in California. Additionally, invasive mollusk species such as the zebra mussel (Dreissena polymorpha), the quagga mussel (D. rostriformis bugensis), and the New Zealand mudsnail (Potamopyrgus antipodarum) have spread throughout California. Both native and invasive mollusks are often present in low abundance, making detection by observation-based surveys a challenge. We are using eDNA to investigate the current distribution of these species in southern California, and collecting water quality data to explore potential correlations between water quality and mollusk presence.

Pictured: Western Pearlshell (Margaritifera falcate)