Date of Award

12-2001

Level of Access

Open-Access Thesis

Degree Name

Master of Science (MS)

Department

Marine Biology

Advisor

Susan Brawley

Second Committee Member

Robert L. Vadas

Third Committee Member

Philip Yund

Abstract

Environmental conditions, such as water motion, can influence fertilization success and spore dispersal in marine algae. Previous studies on fucoid algae showed that gamete release is restricted to, or enhanced by, periods of low water motion. Few other algal taxa have been investigated, however, including species with an alternation of generations. I investigated gamete and spore release in the macroalgae Alaria esculenta and Ulva lactuca, as well as in the diatom Pseudo-nitachia multiseries to determine if water motion is inhibitory or stimulates propagule production and release. I used orbital shakers to simulate water motion; these were interspersed with stationary platforms within a walk-in culture chamber. Gamete and zoospore release (A. esculenta and U. Itrctuca) or gamete and zygote production (P. multiseries) were determined daily for several days. Alaria esculenta released a significantly higher number of zoospores under turbulent conditions (P = 0.0001, 2-way ANOVA) and a higher number of sperm under calm conditions (P = 0.0052, 2-way ANOVA). Juvenile A. esculenta sporophytes were present in significantly higher numbers in calm treatments (P = 0.001 2-way ANOVA; contact time, male + female gametophytes = 150 min). Turbulent conditions resulted in a significantly higher release of both gametes (P = 0.0021, 2-way ANOVA) and zoospores (P = 0.0028, 2-way ANOVA) in Ulva lactuca. Pseudo-nitzschia multiseries had significantly higher gametogenesis under calm conditions in one mating cross (P = 0.0055) but not in the other cross. A significantly higher number of zygotes were produced under calm conditions (P = 0.0001, 2-way ANOVA) in all crossed strains of P. multiseries. These data demonstrate that different algal taxa have varying reproductive responses to water motion. The results are of interest with respect to life-history adaptation and fertilization success.

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