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Thesis - NSU Access Only
M.S. Marine Biology
Water flow is an important abiotic factor for corals and other cnidarians. This study shows how water flow influences bleaching in Palythoa caribaeorum. Colonies were exposed to flow (low = 3 cm s-1, high = 15 cm s-1) in two temperature regimes (low: 26.5°C, which is within natural variability on the reef where specimens were collected; high: 33.5°C, which is 3.5°C above usual summer temperature) in a unidirectional flume for 48 hours. Two sizes (small = 2.3 ± 0.2 cm, large = 7.3 ± 0.4 cm in diameter) were tested in six repeats per flow regime. Bleaching was determined by zooxanthellae count using a hemocytometer and by chlorophyll a concentration using fluorometry. Results suggest that onset of bleaching is rapid (within 48 hours) in high temperature. The low temperature did not cause significant bleaching. In the high temperature treatment, P. caribaeorum consistently bleached less in high flow. Upstream sides of large colonies bleached less than the downstream sides in high flow. In high flow, small colonies bleached less than large colonies. This suggests that enhanced diffusion of toxic oxygen species is important to mitigate bleaching and is more easily accomplished in small colonies, which may thus have an advantage during bleaching events, as has been observed in the literature.
Atsushi Fujimura. 2010. Effects of Water Flow on Bleaching of Palythoa Caribaeorum. Master's thesis. Nova Southeastern University. Retrieved from NSUWorks, Oceanographic Center. (220)