The State of the Mediterranean Marine and Coastal Environment

et al. 1998; Crispi et al. 2002; Bosc et al. 2004). According to recent estimates by Ludwig et al. (2009) the maximum primary produc- tion that can be supported by the riverine nutrient inputs is only about 1–2 % of the total primary production in the Mediterrane- an. In coastal areas with large rivers, however, this contribution can be much more important. Changing river nutrient loads may therefore have a substantial impact on biological productivity in the more productive river-dominated coastal systems, such as the Adriatic Sea.

silicon outflow. Bethoux et al. (1992) proposed that, at a basin scale, the phosphorus deficit would be balanced by runoff from land and atmospheric deposition, while nitrogen losses might be balanced by additional fixation by sea grass epiphytes and pelagic bacterioplankton. Mean annual gross primary production (PP) in the Mediterra- nean Sea is estimated at about 110–120 g C/m 2 for the Eastern Basin and about 120–160 g C/m 2 for the Western Basin (Bethoux

LUXEMBOURG

CZECH REPUBLIC

SLOVAKIA

Surface circulation in the Mediterranean Sea

Main path

Secondary path or recirculation Dense water formation zone Mesoscale gyres Seasonal path

Sources: C. Millott and Taupier-Letage, I. (2005). Circulation in theMediterranean Sea. Hdb Env Chem Vol. 5, Part K, 29–66

MALI

Chlorophyll-a concentration

NIGER

CHAD

Climatological yearly mean, 1998-2003 Milligrams per cubic metre

1

100

0.01

0.1

Source: adapted fromV. Barale, Jaquet J. and M. Ndiaye (2008). Algal blooming patterns and anomalies in the Mediterranean Sea as derived from the SeaWiFS data set (1998–2003). Remote Sensing of Environment 112, 3300–3313.

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INTRODUCTION TO THE MEDITERRANEAN BASIN