Seasonal variation of riverine nutrient inputs in the northern Bay of Biscay (France), and patterns of marine phytoplankton response

Type Article
Date 2008-07
Language English
Author(s) Guillaud Jean-Francois1, Aminot Alain1, Delmas Daniel2, Gohin Francis1, Lunven Michel1, Labry Claire1, Herbland Alain3
Affiliation(s) 1 : IFREMER, Dept DYNECO, F-29280 Plouzane, France.
2 : IFREMER, Dept AGSAE, F-17137 Houmeau, France.
3 : IFREMER, Dept AQUACAL, F-98846 New Caledonia, France.
Source Journal of Marine Systems (0924-7963) (Elsevier), 2008-07 , Vol. 72 , N. 1-4 , P. 309-319
DOI 10.1016/j.jmarsys.2007.03.010
WOS© Times Cited 32
Keyword(s) Northern Bay of Biscay, phytoplankton, continental shelf, riverine inputs, Nutrients
Abstract Seasonal variations in nutrient inputs are described for the main rivers (Loire and Vilaine) flowing into the northern Bay of Biscay. The river plumes are high in N/P ratio in late winter and spring, but not in the inner plume during the summer. Conservative behavior results in most nutrients entering the estuary and eventually reaching the coastal zone. Temporal and spatial aspects of phytoplankton growth and nutrient uptake in the northern Bay of Biscay distinguish the central area of salinity 34 from the plume area. The first diatom bloom appears offshore in late winter, at the edge of the river plumes, taking advantage of haline stratification and anticyclonic "weather windows." In spring, when the central area of the northern shelf is phosphorus-limited, small cells predominate in the phytoplankton community and compete with bacteria for both mineral and organic phosphorus. At that period, river plumes are less extensive than in winter, but local nutrient enrichment at the river mouth allows diatom growth. In summer, phytoplankton become nitrogen-limited in the river plumes; the central area of the shelf is occupied by small forms of phytoplankton, which are located on the thermocline and use predominantly regenerated nutrients.
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Guillaud Jean-Francois, Aminot Alain, Delmas Daniel, Gohin Francis, Lunven Michel, Labry Claire, Herbland Alain (2008). Seasonal variation of riverine nutrient inputs in the northern Bay of Biscay (France), and patterns of marine phytoplankton response. Journal of Marine Systems, 72(1-4), 309-319. Publisher's official version : https://doi.org/10.1016/j.jmarsys.2007.03.010 , Open Access version : https://archimer.ifremer.fr/doc/00000/2354/