The effects of induced interaction with Dreissena polymorpha on Limnephilidae larval substrate choice

Abstract

In many freshwater ecosystems of the Northeastern United States, the invasive Dreissena polymorpha (zebra mussels) are causing a wide range of both biotic and abiotic changes. We inquired into the potential interactions between caddisfly larvae (order Trichoptera, family Limnephilidae) and zebra mussels at the mouth of the Maple River in Douglas Lake (Cheboygan County, Michigan). Specifically, we wanted to determine if the presence of D. polymorpha had an effect on substrate preference of Limnephilidae larvae in a laboratory setting. The experiment involved recording the position of caddisfly larvae within an aquarium. Two aquarium setups were arranged so that the larvae could move between two different substrates; one tank type contained sand and live zebra mussels attached to rocks (treatment tanks) and the other (control tanks) contained sand and rocks. This experiment was performed at a low and high larval density. We found that the Limnephilidae larvae had a statistically significant preference for substrates containing live zebra mussels and that over time Limnephilidae larvae increasingly preferred the live zebra mussel substrate (at high larval density). Furthermore, in the low-density control tanks we found that over time Limnephilidae larvae tanks preferred the sand substrate more than the rock substrate.