Planktic response to seasonal oceanographic changes in the Alboran Sea (Western Mediterranean). Sediment trap record
Abstract
The Alboran Sea is the westernmost basin of the Mediterranean. The circulation of the Alboran Sea is subject to strong seasonal variations related to fluctuations in the intensity of water exchange through the Strait of Gibraltar. The Western Alboran Gyre (WAG) is a system of high biological productivity where an upwelling of subsurface waters occurs. The area also receives an additional contribution of nutrients due to partial enrichment of the Atlantic Surface Water as it passes through the Gulf of Cadiz and the Strait of Gibraltar. Satellite images reveal that these feature gyres are unstable. In order to monitor fluxes of major constituents in the WAG a mooring array with two Technicap PPS3 sediment traps were deployed during the period July 1997 to May 1998. The mooring line was deployed over the continental slope (36o15'N, 04o16'W) at 1004 m water depth. Sets of SeaWiFS (Sea-viewing Wide Field-of-view Sensor) chlorophyll-a concentration images (chl-a mg”m-3), showing a monthly pattern of the WAG, were used to monitor and to contrast the sedimentary fluxes. For this work, fluxes of diatoms, coccolithophorids and foraminifera, as well biogenic opal, calcium carbonate and TOC were evaluated. Three episodes with increased flux have been observed in all the studied parameters: July, November-December, and April-May, in agreement to the observed with satellite images. This allows us to define three periods or peaks of higher productivity: Summer peak, Fall peak and Spring peak. Spring and Summer peaks are relatively richer in organic matter, biogenic opal and phytoplankton (coccolithophores and diatoms), than Fall peak. Thus we conclude that phytoplankton production is the main mechanism of controlling particles fluxes in spring and summer, but during fall it is also controlled by fluvial discharges (fresh water input).
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2001
- Bibcode:
- 2001AGUFMPP42A0483B
- Keywords:
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- 1724 Ocean sciences;
- 3030 Micropaleontology;
- 4267 Paleoceanography