Date of Award


Level of Access Assigned by Author

Campus-Only Thesis

Degree Name

Master of Science (MS)


Marine Biology


J. Malcolm Shick

Second Committee Member

Les Watling

Third Committee Member

David W. Townsend


Scleractinian, or hard, corals have become increasingly popular in the home aquarium hobby. However, unlike soft corals, the scleractinians grow very slowly. Therefore, their artificial propagation through aquaculture is relatively rare, and most specimens on the commercial market are taken directly from the sea. The combination of slow growth and popularity of the scleractinians creates a dangerous potential for reef degradation if too many are collected. However, if the rate of growth could be substantially increased without incurring a proportional rise in the cost of production, the commercial potential of scleractinian corals for aquaculture would be enhanced. The purpose of this project was to explore the possibility of artificially enhancing calcification (and thereby, growth) in a commercially popular scleractinian coral, Porites rus, through the addition of inorganic carbon (sodium bicarbonate). Two sets of coral nubbins (fragments) from the same colony were incubated in two alkalinity regimes (3.85 and 6.16 mM TA) over a period of 80 days. The nubbins that were incubated in high alkalinity seawater exhibited significantly more growth than their counterparts (15.8% vs. 3.2% increase in weight). Additionally, nubbins that exhibited "inferior" health (those that never fully extended their polyps) were found in both groups in equal number. Even the nubbins showing inferior health that were exposed to the high alkalinity treatment had significantly more growth than the healthy nubbins incubated at lower alkalinity (11.2% vs. 4.9% increase in weight). This project has shown that the growth of Porites rus can be substantially increased by the addition of relatively inexpensive sodium bicarbonate.