Date of Award

8-2007

Level of Access

Open-Access Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Marine Biology

Advisor

David W. Townsend

Second Committee Member

Linda Kling

Third Committee Member

Denise Skonberg

Abstract

This project sought to determine if flame angelfish (Centropyge loriculus) could serve as models in examination of environmental and dietary effects on egg quality in marine fishes. Evaluation of 21 marine ornamental species identified flame angelfish as being amenable to egg quality research, due to their rapid conditioning and frequency of spawning. At the onset of this project, accidental copper introduction to broodstock systems required assays to determine the effects of copper exposure on survival and reproduction. Flame angelfish exhibited accute sensitivity to copper, as 60% of fish exposed to 0.25mg/L died within 12 hours of exposure. Likewise, fish exposed to 0.20 and 0.15mg/L exhibited 40% mortality within 48 hours. Furthermore, copper at 0.10mg/L significantly reduced fecundity and negatively affected embryonic development among orchid dottyback (Pseudochromis fridmani) broodstock. A series of experiments was conducted to determine the effects of water chemistry and broodstock diet on flame angelfish reproduction, as well as to compile baseline spawning performance and egg quality data for this species. Results revealed that water chemistry significantly affected spawning performance, as fish maintained in sterilized ocean water exhibited greater fecundity, egg fertilization rates and egg viability than pairs held in water from saltwater wells. However, sterilization of ocean water by chlorine at levels >25ppm significantly reduced fecundity and egg fertilization. Flame angelfish readily adapted to a variety of formulated feeds and results from current experiments demonstrated that maternal diet significantly affected egg quality. Fish that were fed a diet containing 3.63% n-3 highly unsaturated fatty acids (HUFA) exhibited significantly greater fecundity, fertilization rates and egg viability than fish that were fed diets with lower n-3 HUFA levels. Furthermore, over-all egg quality, egg and larval size metrics, and survival to yolk-exhaustion, were not significantly different between fish fed the High n-3 and Control diets. Daily egg production from 18 pairs was recorded over a 20-month period and averaged 1,000-1,500 eggs per female. Mean daily egg fertilization rates ranged from 60-80% and hatch rates were normally 80%. Egg quality characteristics responded to maternal dietary changes within weeks, indicating that experiments of shorter duration than those currently reported may be possible.

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