Red sea gravity currents cascade near-reef phytoplankton to the twilight zone

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

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Official URL: http://edoc.unibas.ch/dok/A5250580

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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.
Faculties and Departments:05 Faculty of Science > Departement Umweltwissenschaften > Geowissenschaften > Aquatic and Isotope Biogeochemistry (Lehmann)
UniBasel Contributors:Niemann, Helge
Item Type:Article, refereed
Article Subtype:Research Article
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:14 Sep 2012 07:21
Deposited On:14 Sep 2012 07:12

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