AUTHORS: Nicholas Iacaruso, University of Illinois Urbana-Champaign, Illinois Natural History Survey; Joel Corush, Illinois Natural History Survey; Mark Davis,University of Illinois Urbana-Champaign, Illinois Natural History Survey
ABSTRACT: Aquatic invasive mollusks (gastropods and bivalves) are among the most ecologically and economically impactful groups of non-native species to the Midwest United States. They can achieve hyper-abundance in freshwater ecosystems, negatively impacting native mollusk biodiversity, damaging infrastructure, altering ecosystem characteristics, and facilitating other invaders. Early detection of new populations before they become hyper-abundant can be an effective strategy for mitigating their worst impacts. However, their small size and cryptic life history often make new invasions difficult to identify. Here, we deploy environmental DNA (eDNA) metabarcoding to detect aquatic invasive mollusks across the Illinois River waterway, an aquatic highway connecting the Mississippi River to the Great Lakes. We focused on six focal species with varying levels of establishment and distribution throughout the Illinois River. We sampled the Illinois River and 24 tributaries over two years to estimate the relative distribution of each invasive mollusk. We also performed eDNA metabarcoding to detect the native mollusk and fish communities in each tributary. We intend to find correlations between the presence of the invasive mollusks and the physical habitat measurements, land-use metrics, or native mollusks and fishes that may inform the current heterogeneous distribution of aquatic invasive mollusks. Our study will also serve as a model for studying the fine-scale spatial distribution of aquatic mollusk eDNA and aid in understanding why some tributaries are more heavily invaded than others.
