Effects of Consumptive and Non-consumptive Predations cues on Caddisfly Detritus Processing

Alston, Aaron

Effects of Consumptive and Non-consumptive Predations cues on Caddisfly Detritus Processing

Persistent URL

http://hdl.handle.net/10456/36076

Author(s)

Alston, Aaron

Date Issued

April 30, 2014

Abstract

The larvae of cased caddisflies (Insecta: Trichoptera: Limnephilidae) occur in pond and stream ecosystems where they feed on detritus (inorganic or organic waste). Limnephilids also use detritus to construct cases around their body that help to protect them from predators, including large invertebrate, salamanders and fish. The focus of this project was on how fish predators affect caddisfly (Nemotaulis ocellifera) foraging behavior, hence the rate of detritus processing. I was especially interested in comparing the consumptive effects of fish to non-consumptive olfactory cues from fish. I hypothesized that caddisfly activity, hence detritus processing should be greatest in the absence of fish and lowest in the presence of actively foraging fish that reduce caddisfly numbers (consumptive effects). The degree to which caddisflies use olfactory cues to detect fish predators will be inferred from whether detritus breakdown rates are more similar to those in the consumptive vs. control (no caddisfly) treatments. I found that caddisflies had the highest detritus breakdown rates in the absence of fish and the lowest in treatments with actively foraging fish. Detritus breakdown rates in the non-consumptive (fish cue) treatments were not different from those in the no-predator treatments, suggesting caddisflies do not change behavior in the presence of only olfactory cues. Across all treatments, the amount of chlorophyll (as a measure of algal biomass) was correlated with detritus breakdown, suggesting that detritus processing by caddisflies has dual ecosystem impacts; i.e., both to the conversion of detrital energy to secondary animal production (caddisfly tissue), and the stimulation of primary productivity for herbivores.

First Reader(s)

Wissinger, Scott