Niemann, H., Richter, C., Jonkers, H. and Badran, M. I. (2004) Red Sea gravity currents cascade near-reef phytoplankton to the twilight zone. Marine Ecology Progress Series (269). pp. 91-99.

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Cross-reef variations of sea water density, currents and phytoplankton pigments were investigated in the northern Gulf of Aqaba, Red Sea. Differential cooling of near- and offshore surface water during cold winter nights results in cross-shore gradients of density (sigma-t) triggering gravity currents which cascade downslope along sandy valleys. Two 4-wk deployments of 3-D acoustic current meters showed that cross-shore currents near the sea bed (35 and 90 m) were 2- to 5-fold higher than long-shore currents, inversely related to surface flow and highly correlated with seasonally detrended diel variations in seawater temperature. Cross-shore flow varied during the course of the night, with offshore pulses of up to 15 cm s(-1) associated with sudden temperature drops of similar to0.15degreesC. Spatial distribution of chl a pigments shows that phytoplankton enriched nearshore waters are entrained in the gravity currents to depths > 300 m. Gravity currents may therefore provide an important and previously overlooked pathway of reef-borne material to the food-impoverished deeper strata of the Red Sea.

Document Type: Article
Programme Area: UNSPECIFIED
Research affiliation: Ecology
Refereed: Yes
Open Access Journal?: No
Date Deposited: 20 Mar 2020 10:35
Last Modified: 26 Mar 2024 13:30

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