Patterns of algal blooming are considered to be indicators of basic ecosystem dynamics in marginal and enclosed seas. A time series of chlorophyll-like pigment concentration (chl)–which can be interpreted as a proxy of biomass and, under certain circumstances, productivity–derived from SeaWiFS data, from July 1999 to June 2009, was considered to explore the space–time variability of algal blooming in the Red Sea. The comparison with concurrent surface wind speed (ws) and direction, derived from QuikSCAT data, allowed to correlate chl variability with atmospheric forcing. The observed chl seasonality is essentially bimodal, with a fall-winter period of extended blooming, progressing from south to north and back, followed by a spring-summer period of reduced blooming, at least in the northern sub-basin. This annual cycle seems to match the climatic characteristics of the basin, the monsoon-driven wind regime in particular, and the ensuing thermohaline circulation. The correlation with ws suggests that the Red Sea behaves like a classical sub-tropical basin, where production is never limited by sunlight, but always limited by nutrient availability–a condition relaxed only in the colder season, when (wind driven) convection processes can enrich the euphotic zone with nutrients from deeper layers. However, at the same time, it appears that other blooming episodes, in the southern sub-basin in particular, are not driven directly by the wind field, but rather by other factors such as the exchange of water with the Arabian Sea, via the Gulf of Aden and Bab-el-Mandeb.
BARALE Vittorio;
GADE Martin;
2014-10-14
Springer Science+Business Media
JRC91275
978-94-017-8007-0,
978-94-017-8008-7,
http://link.springer.com/chapter/10.1007%2F978-94-017-8008-7_17,
https://publications.jrc.ec.europa.eu/repository/handle/JRC91275,
10.1007/978-94-017-8008-7_17,
