Atmospheric Deposition Controls On The East Mediterranean Marine Ecosystem

Atmospheric deposition is known to be a significant source of nutrients for the marine environment. Increased knowledge of the interactions between atmospheric deposition of nutrients and ocean productivity is of great importance for both carbon dioxide (CO2) storage in the ocean and marine ecosystems life. These interactions can vary spatially and temporally, changing the role of the ocean from a sink to a source of CO2 and vice versa. Mediterranean Sea is one of the world's most oligotrophic ecosystems and presents an unusually high Nitrogen-to-Phosphorus ratio (N:P) in the eastern (28:1) basin. In this basin, where riverine nutrient inputs are negligible, N and P atmospheric deposition is believed to be the main source of nutrients in the euphotic zone of the open sea. In the present study, the impact of the inorganic N and P atmospheric deposition on the marine ecosystem in the East Mediterranean Sea is investigated by using a 1-D coupled physical/biogeochemical model (Christodoulaki et al., 2012, Journal of Marine Systems, doi: 10.1016/j.jmarsys.2012.07.007). The model is set-up for the Cretan Sea as a representative area of the Eastern Mediterranean Basin and is forced by observations of atmospheric deposition over Crete Island. The results show that atmospheric deposition can be the responsible mechanism for the unusually high N/P analogy. The impact of the atmospheric deposition on the primary production and population distribution is also calculated. The contribution of human activities in these impacts is estimated. The robustness of these findings is evaluated based on additional sensitivity simulations.