Factors Limiting Colonization of Western New York Creeks by the Zebra Mussel (Dreissena polymorpha)

Abstract

The New York State Erie Barge Canal was first colonized by the zebra mussel (Dreissena polymorpha) in 1989. Canal water supplements flows in many creeks in western New York, including six creeks in Monroe County that have not been colonized by zebra mussels. We chose Salmon Creek to study why zebra mussels have not colonized regional creeks because the rocky substrate of the creek appears ideal for colonization, yet 100 meters downstream from the input of canal water to the creek adult zebra mussel densities drop to less than one mussel m−2. In the summer of 1993 veliger counts in the canal averaged 52 times greater than they were in Salmon Creek, yet water quality, current velocity, and particulate organic carbon concentrations in the creek and the canal were very similar. Chlorophyll a in the canal was higher than in the creek. Given the appropriate physical habitat and water quality conditions and an abundant source of veligers, the factors limiting zebra mussel colonization in Salmon Creek remain unknown, but three factors appear important: 1) Partial retention of zebra mussel veligers by the wetland through which the canal discharge flows, 2) Filtering of phytoplankton and veligers by the dense bed of adult zebra mussels at the beginning of the outfall channel from the canal to the creek, or 3) Inappropriate food quality (e.g., lack of phytoplankton with important fatty acid constituents) in the creek.