ABSTRACT
Dreissenid mussels were sampled along a 300 km section of the Erie Canal between Buffalo and Syracuse, New York, over the period 1991-2009. Samples were collected at 2 sites in summer 1991, 20 sites in 1993, and unevenly (temporally) at up to 21 sites through winter 2009. Zebra mussels (Dreissena polymorpha) were found at all sites and dominated the population early in the study period. However, over time, quagga mussels (Dreissena rostriformis bugensis) made up an increasing proportion of the dreissenid population. Quagga mussels expanded their range from west to east and, by 2009, were found at all sites. Also, quagga mussels displaced zebra mussels as the dominant dreissenid mussel (near 100%) at many sites, particularly those sites in the western portion of the canal that were colonized by quagga mussels early in the study period. The percentage of quagga mussels varied widely between sites by 2009, but it was not apparent if this was a result of the west to east expansion or a difference in rate of increases at various sites. Regardless, the increasing dominance of quagga mussels provided evidence that quagga mussels can outcompete zebra mussels under the low-ow and shallow-warm conditions found in the canal.
