Internal circulation

Abstract

A number of processes result in hydraulic gradients that drive internal circulation on coral reefs at a range of time and space scales, including wave setup, lagoon drainage, tides, and other regional currents, density gradients, groundwater flow, and oscillatory waves. Some flows, such as wave driven pore-water circulation can be very fast, resulting in large water turnover between surface and subsurface sediments, over relatively small areas, whereas at the other end of the spectrum, slow flows driven by other mechanisms affect large volumes of framework, over periods extending from years to geologic time. Field studies have indicated flow through reef framework in the order of tens of meters per day, with water moving in high permeability zones such as cavities and rubble dominating bulk flow.