Chlorophyll signatures and nutrient cycles: Mediterranean sensitivity to nitrogen and phosphorus depositions

The distribution of nutrients within biochemical compartments is analysed, highlighting the role of ultraplankton, the smaller phytoplankton compartment, in the oligotrophic environment of the Mediterranean Sea. For all three cases, the estimated primary production in the western basin is about twice as high as in the eastern basin, while the secondary production in the west is about three times as high as in the east. This numerical sensitivity analysis suggests that the ecosystem is on the edge of a top-down control of netplankton in the western basin and a more nutrient-depleted regime in the eastern basin. (Abstract Excerpts)