Masters Theses

Date of Award

8-1996

Degree Type

Thesis

Degree Name

Master of Science

Major

Ecology and Evolutionary Biology

Major Professor

James A. Drake

Committee Members

Dewey Bunting, Stuart Pimm

Abstract

Originally, this work was intended to investigate the influence of food chain length on primary producers in a set of artificial streams constructed in the laboratory. The idea was to use a controlled species pool to assess the differences in biomass and species composition between streams with one, two, and three trophic levels. However, the streams proved to be resistant to attempted animal invasions. The focus of the study then became the possible factors affecting the survival of these animals in the artificial streams. Hyallela azteca (Amphipoda) and Goniobosis (snails) were repeatedly introduced, between small modifications designed to increase their survival. Additionally, an experiment was carried out in which the type of growing medium was examined for its effects on Goniobosis survival. Results indicated that Goniobosis survived best in a more natural medium, one which would make a controlled species pool difficult to maintain. Also, they survived better in media kept at a pH around 7 rather than the pH of 10 maintained by the original chemical medium. For future investigations, the chemical medium must be altered to extend animal survival even longer in the streams. Changes in pH, reduction of possibly toxic micronutrients, and faster turnover of the media are recommended. Alternatively, a more natural medium may be used, but studies requiring a controlled species pool would be more difficult to perform. Also suggested in this paper is introduction of animals earlier in the assembly period of the primary producers, to facilitate their invasion success.

Download
Files over 3MB may be slow to open. For best results, right-click and select "save as..."

Share

COinS