Date of Award

Summer 2010

Document Type

Legacy Thesis

Degree Name

Master of Science in Coastal Marine and Wetland Studies

Department

Coastal and Marine Systems Science

College

College of Science

First Advisor

Sharon L. Gilman

Second Advisor

Christopher Binckley

Third Advisor

Kevin S. Godwin

Additional Advisors

Deborah Hutchinson

Abstract

Patterns of insect colonization are influenced by biotic and abiotic factors. This experiment examined the degree to which canopy coverage and the presence of non-lethal predators affected oviposition site choice by aquatic insects. Twenty-four experimental ponds (415 L polytanks) were divided equally among treatments (i.e., open or closed canopy and presence or absence of fish) and set up into six spatial blocks of four tanks each. Ponds were colonized by ovipositing aquatic insects and a total of 1,592 individuals constituting eight genera were recovered from the experimental ponds. Significant differences were found between closed-canopy and open-canopy ponds in diversity (p < 0.01) and species richness (p < 0.01), due to insects choosing closed-canopy ponds. Canopy-covered ponds received almost 75% of insect colonists. No significant differences in insect richness (p = 0.53), total abundance (p = 0.36), or individual species abundance (p > 0.05) were found between predator treatments. However, diversity was significantly different between predator-free and predator-containing tanks (p = 0.03), due to insects choosing for predator-containing tanks. Only one species (Hydaticus bimarginatus) had a significant predator by canopy interaction (p < 0.01), choosing for predator-containing/closed-canopy tanks. Weather conditions and physical parameters varied throughout the experiment and were not significantly different between treatments (p > 0.05); however, 69% of total cumulative variation was explained by barometric pressure and precipitation. The results of this project suggest that canopy coverage and weather conditions are important in predicting colonization and abundance of aquatic insects.

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