An Evaluation of Plankton Sampling Methods to Detect Zebra Mussel Veligers in a Newly-Infested Kansas Reservoir

Zebra Mussels Dreissena polymorpha are an invasive mussel that negatively impact aquatic ecosystems outside their native range. Movement of live adults or water containing zebra mussel veligers results in the continued spread and establishment of new populations. Early detection provides an opportunity for managers to deploy rapid response strategies and to allow stakeholders to prepare for potential impacts. A common method for detecting new populations is to examine plankton samples for the presence of zebra mussel veligers using cross-polarized light microscopy, yet there is no standard procedure for plankton sample collection. The objective of this study was to evaluate which sampling techniques and locations were most likely to detect zebra mussel veligers in a newly discovered, low density population at Pomona Reservoir, Kansas. We used a Wisconsin-style plankton net to collect samples from main lake sites and 50 meters offshore from boat ramps using vertical tows, and from boat ramp docks using surface, vertical, and oblique tows. Samples taken at boat ramps using oblique and vertical tows contained the highest veliger densities. Additional results will be discussed to inform managers the best method to detect zebra mussel veligers in the most efficient, cost-effective manner.