Interdisciplinary Initiatives Program Round 1 - 2000

Stephen Monismith, Civil & Env. Eng.
Greg Shellenbarger, Civil & Env. Eng.
Adina Paytan, Geologic and Env. Sciences

This research project focuses on the role played by physical forcing, i.e., currents and turbulent mixing, in determining the way in which coral reefs maintain high biological productivity despite the fact that they are generally found in oceanic regions that are otherwise remarkably unproductive. The key to this paradox, originally posed by Darwin, is that reefs may be remarkably efficient at extracting materials from the adjacent ocean. However, if this is the case, then the flow of food (nutrients and plankton) may be limited by the rate at which food-depleted water in contact with the reef can be replaced by water with higher concentrations of food.

To test this hypothesis, simultaneous measurements of currents, and of phytoplankton (algae) and nutrient distributions in space and time were made over the fringing coral reef found at Eilat, Israel. However, quantifying offshore-onshore exchanges of fluid is critical yet difficult to do accurately.

A novel aspect of the work is the use of naturally occurring radium isotopes derived from groundwater sources to identify terrestrial nutrient sources entering from submarine groundwater flows and as natural markers that the researchers can compute the rate of exchange of waters over the reef with the waters of the adjacent Gulf of Aqaba, a branch of the Red Sea.