In the marine environment salinity and biological pumps sequester atmospheric CO2. Biological pump is related to marine primary production which in turn is controlled by nutrient availability mainly of iron, nitrogen (N) and phosphorus (P). Mediterranean Sea (MS), especially the eastern basin is one the most oligotrophic seas. The N/P ratio is unusually high with a west (22:1) to east (28:1) increasing gradient resulting in a P limited primary production. Atmospheric deposition was recently suggested as the main external mechanism of nutrients supply to the marine environment. Measurements of deposition show significant nutrient fluxes towards the sea but their exact role to the marine ecosystem has not been established.
The proposed project aims at quantifying the role of atmospheric deposition of nutrients as a driver for changes in marine productivity through modeling and experimental work. This will be achieved by coupling atmospheric and sea-water observations and combine them with a marine biogeochemical/ecosystem model forced by an atmospheric chemistry/transport/deposition model.
The atmospheric deposited nutrients, their anthropogenic component and their long-term variability (hindcast and forecast simulations) will be examined and followed by an evaluation of the oceanic biogeochemistry response to these forcings.
The workpackages include drivers of change in marine ecosystems, atmospheric modeling, MS ecosystem modeling and output dissemination (http://www.thales-adamant.hcmr.gr/). Results from the experimental and modeling components of the work carried out will contribute towards better understanding of the MS biogeochemical functioning and how this is influenced by anthropogenic activity and climatic changes. This will provide new insights in the current state and function of the ecosystem whereas the modeling effort will contribute towards the establishment of possible indicators of change and of processes which require further in depth examination.