The transport of nutrient-rich Indian Ocean water through the Red Sea and into coastal reef systems
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Driven by upwelling-favorable monsoon winds, nutrient-rich Gulf of Aden Intermediate Water (GAIW) enters the Red Sea from the Indian Ocean each summer. Hydrographic and velocity data acquired in autumn 2011 provide the first indication that GAIW is carried rapidly northward along the eastern Red Sea margin in a well-defined subsurface current with speeds >30 cm s(-1). The nutrient-rich (NO2 + NO3 concentrations up to 17 mu mol l(-1)) GAIW overlaps the euphotic zone and appears to fuel enhanced productivity over depths of 35-67 m. GAIW is broadly distributed through the Red Sea, extending northward along the eastern Red Sea boundary to similar to 24 degrees N and carried across the Red Sea in the circulation of a basin-scale eddy. Of particular significance is the observed incursion of GAIW into coastal areas with dense coral formations, suggesting that GAIW could be an important source of new nutrients to coral reef ecosystems of the Red Sea.