27 Mar 2020
New comprehensive model implemented in the Mediterranean
The Mediterranean is considered a ‘hot spot’, as it is sensitive to both human pressure resulting from higher population and development in coastal areas, and to climate change.
A team of research, amongst whom are CLAIM members, implemented a new comprehensive biogeochemical model, which describes with the necessary complexity the Mediterranean planktonic food web and biogeochemical processes. It is currently in operation as part of the POSEIDON forecasting system, providing short-term predictions.
The three-dimensional coupled hydrodynamic/biogeochemical numerical model was assessed regarding its efficacy in representing the main biogeochemical components and seasonal dynamics of the Mediterranean planktonic system. Model outputs were compared with available historical data in a proposed objective eco-regionalisation of the Mediterranean basin, based on productivity. The simulated production (primary, bacterial) and planktonic biomass (phytoplankton, zooplankton and bacteria), as well as particulate and dissolved organic carbon, are considered consistent with observational estimates in different areas of the Mediterranean Sea, following large scale productivity gradients. Although researchers identified some limitations of the model, the observed variability of the phytoplanktonic community structure was reasonably well-reproduced, simulating a dominant microbial food web with an intermittent development of the classical food web.
Model simulated mean (1990–2009) spatial distribution of 0–100m average a) net primary production (mgC/m3/d), b) bacterial biomass (mgC/m3), c) bacterial production (mgC/m3/d), d) phytoplanktonic biomass (mgC/m3), e) DOC (mmol/m3) and f) POC (mmol/m3).
The generic POSEIDON ecosystem model skill assessment provides a benchmark for future model improvement, highlighting the need to expand the range of biological variables sampled for further model calibration and validation.