Meeting Abstract
The wide scale increase in infrastructure associated with a growing human population has rapidly intensified habitat fragmentation, a primary contributor to biodiversity loss. Within aquatic ecosystems, one mechanism for fragmentation is the installation of culverts at road-stream intersections. These structures have the potential to alter ecosystem function by increasing flow velocity and turbulence within the water column. Crayfish are keystone organisms that often migrate upstream in search of resources and consequently need to move through culverts. To investigate whether culverts have the potential to fragment crayfish habitat, we conducted 24 hour behavioral studies wherein crayfish were videotaped in four mesocosms simulating a divided stream. Each mesocosm contained a channel filled with either corrugated pipe material or a gravel/sand mixture connecting an upstream and a downstream section. Additionally, we varied the flow in the mesocosms, with a faster flow treatment (3.30 L/s to 3.90 L/s) and a slower flow treatment (0.14 L/s to 0.22 L/s). Videos were analyzed for the number of crossings through the channel, the duration of each crossing, and whether the animal was moving upstream or downstream. The sex and sizes of the crayfish were also analyzed to determine if these factors influenced crossing behavior. Road-stream crossing surveys were conducted to investigate potential habitat heterogeneity and crayfish population demographic differences upstream and downstream of culverts and bridges. Results indicate that the degree of stream fragmentation varies with crossing type, creating potential divisions between reaches of a stream as well as a potential opportunity for the spread of invasive species.
