Effect Of Channelization On Macroinvertebrate Species

Bridges and box culverts channelize streams and rivers and have the potential to drastically affect biological communities. Bridged streams and rivers can be divided into three areas: the upstream area, the channelized area, and the downstream area. Because bridges are frequently adjacent to more typical stream reaches, they offer an opportunity to study the immediate effects of channelization on otherwise typical benthic communities.  Studies on the effects of river bridges on macroinvertebrates communities are scarce. To measure the effects of bridge channelization on invertebrate communities, we sampled replicated benthic communities, upstream of bridges, in bridges, and downstream of bridges.  Samples were collected from four streams, representing three structural bridge types (Aluminum box culvert, bridge, and concrete box culverts). In each lotic habitat, four replicate samples were taken at the upstream area, inside the bridged channel, and downstream. In addition, a general site assessment was performed and bridges were measured. Then the macroinvertebrate samples were counted and identified to genus. Preliminary data from two sites show that the upstream have the highest macroinvertebrate diversity. At the upstream in Potash Brook there were seventeen taxa and in Browns River fifteen taxa. Samples from under bridges have the lowest diversity with six taxa in Potash and ten taxa in Browns. At the downstream, there were a small variety of species with fourteen taxa in Potash and twenty-one taxa in Browns. The measurement of bridge effects is crucial in ecological and biological surveys of streams because many such studies are performed close to bridges.