Small-Scale Upwelling as a Control for Reef Health and Frameworks, Preliminary Findings from the Bahamas and the Arabian Sea
9th International Coral Reef Symposium, Bali, Indonesia, October 23-27, 2000
Coral health and framework development was investigated in Eleuthera, Cat Island (Bahamas) and Khor Fakkan (Arabian Sea, United Arab Emirates) in 1999. In the Bahamas, coral cover and reef framework development was found to be better in Eleuthera than in Cat Island. However, coral mortality, bleaching and disease frequency was much higher in Eleuthera than in Cat Island. Repeated small-scale upwelling of water about 2 degrees colder than surface waters was observed on Cat Island and the shelf-edge reefs were covered by this water. It is assumed that in bleaching years, when sea-surface temperatures are elevated and corals bleach, such moderate upwelling can protect the Cat Island corals from bleaching. The coral’s price for this protection is the disadvantage of having to live in a colder environment with ensuing lower calcification and frame building rates. In the Arabian Sea, Shark Island experiences frequent small-scale upwelling events which lead to a temperature stratified water column. Pocillopora frameworks were found to be dead above 5m but completely alive underneath. The geometry of the reef and the mortality signs allow speculation that this mortality in shallow water was also caused by surface waters heated above bleaching threshold, while corals growing in water deeper than 5m were protected by cool, upwelled water.
Riegl, Bernhard and Piller, Werner, "Small-Scale Upwelling as a Control for Reef Health and Frameworks, Preliminary Findings from the Bahamas and the Arabian Sea" (2000). Oceanography Faculty Proceedings, Presentations, Speeches, Lectures. 86.