The effects of culverts on the upstream migration patterns of Orconectes sp.

Abstract

The East Branch of the Maple River contains crayfish species, Orconectes sp., which depend on upstream migration for successful repopulation and distribution in this and other lentic systems. This genus of crayfish provides usuable forms of energy to higher trophic levels through its ability to convert many forms of allochthonous detrital materials at a faster rate than many other aquatic consumers. Experimental studies were designed to quantify and qualify the possible limitation of culverts on this upstream migration habit of Orconectes sp. This potential limitation may impede the ecological energy cycling of such aquatic systems. Densities were observed to be higher at the outflow areas of the stream culverts than at the inflow areas at two sites on the Maple River, indicating that crayfish densities possibly decrease upstream with increasing numbers of culverts. Substrate, however, may have alternatively played a crucial role in the observed distributions and abundances. Other limitations of the design of this experiment are posed to aid in the design of future experiments.