UPSTREAM MIGRATION OF FAXONIUS RUSTICUS IN TRIBUTARIES OF THE MONOCACY RIVER AND COMPARISON OF TWO SAMPLING METHODS TO QUANTIFY CRAYFISH ABUNDANCE

Abstract

The rusty crayfish, Faxonius rusticus, has invaded many of the United States freshwater ecosystems, including the Monocacy River in central Maryland. Prior to this study, the movement of F .rusticus within the Monocacy had only been analyzed in a downstream direction. We hypothesized that F. rusticus is also capable of spreading upstream within the Monocacy River system. Sampling nine of the tributaries to the Monocacy River revealed that since 2007 F. rusticus moved upstream at a minimum rate of 0.5 km (yr-1). We also sought to compare the kick seine and quadrat sampling methods for possible biases. Our findings show that the quadrat sampling method is more capable of catching smaller crayfish than the kick seine and can catch more crayfish (m-2) on average. These findings advance our knowledge of how F. rusticus spreads through an ecosystem and give insight into when it’s appropriate to use the quadrat or kick seine.