Estimating sampling effort for early detection of non-indigenous benthic species in the Toledo Harbor Region of Lake Erie

Abstract

Toledo Harbor (Maumee River and Maumee Bay) is a “port of concern” for introduction of non-indigenous species into the Great Lakes due to the large amounts of ballast water from outside the Great Lakes discharged at the port, the amenable habitat for many potential invasives, and the large amount of ballast water transported from Toledo to other Great Lakes ports, making Toledo a potential source of invasives throughout the entire region. To estimate sampling intensity needed to detect rare or new non-indigenous species, 27 benthic grab samples from 13 locations near Toledo Harbor were collected during autumn, 2010. Benthic organisms were identified, and sampling intensity needed to detect rare or new non-indigenous species was evaluated via a Chao asymptotic richness estimator. Morphological taxonomic criteria and cytochrome oxidase I (COI) sequence barcodes identified 29 different taxa (20 to species level) in the samples, including six non-indigenous taxa (Branchiura sowerbyi, Bithynia tentaculata, Corbicula fluminea, Dreissena polymorpha, Dreissena bugensis, Lipiniella sp.). While all the non-indigenous species had previously been reported in Lake Erie or nearby Ohio waters, several North American species are not previously listed in Ohio. Richness estimates indicate that >75% of the benthic species in the area were encountered and that 90% of the species could be detected with less than a doubling of collecting effort. Since sampling for this study occurred only in the autumn and detectable life stages of benthic organisms may vary seasonally, additional species may be observed with more extensive sampling over a broader seasonal range.