Does the Presence of Brook Trout Influence the Benthic Insect Community in a Headwater Stream?

Brook trout (Salvelinus fontinalis) are native predators in New Hampshire streams, feeding upon a variety of invertebrates. We investigated whether the presence of brook trout might influence the benthic insect community in a headwater stream. To do this, we sampled at three different locations in Kineo Brook at the Hubbard Brook Experimental Forest. The first location was immediately upstream of a cascade, in a section of stream where brook trout did not occur. The second location was immediately downstream of this barrier to trout dispersal, where fish were present. The third location was even further downstream, closer to the confluence of Kineo Brook with Hubbard Brook. We used a Surber net to collect five to six samples of benthic insects at each location in August 2019. We also set up three rock baskets per sampling location. Rock baskets were placed during the month of August in pools deep enough to cover the baskets completely, and they were retrieved in October. All samples were preserved in ethanol and identified to family. We compared the abundance, diversity, and composition of the benthic insect samples between different locations and between our two sampling methods