Scenario simulations of the changing Black Sea ecosystem (SIMSEA)

The regional Black Sea ecosystem model (BSEM) has been applied for the first time for biogeochemical simula­tions of the Black Sea ecosystem (Oguz, T., H. W. Ducklow, J. E. Purcell, and P. Malanotte-Rizzoli (2001), Modeling the response of topdown control exerted by gelatinous carnivores on the Black Sea pelagic food web. J. Geophys. Res., 106, 4543–4564). The BSEM model is able to describe the Black Sea specific features as demonstrated by the analysis presented herein. One of the key modification of the existing models is the introduction of two new components - the carnivore predators Mnemiopsis and Noctiluca shunt. Originally they began to exist in the lower trophic Black sea food web since the 80s. They feed on zooplankton and are responsible for the reduction of zooplankton standing stock that represents an ecological concern. Detailed description of the BSEM can be found in Miladinova S., A. Stips, E. Garcia-Gorriz, D. Macias Moy (2016c), Modelling Toolbox 2: The Black Sea ecosystem model, EUR 28372 EN, doi:10.2788/677808. The model is coupled to the General Estuarine Transport Model (GETM). It is forced with fluxes, obtained from realistic meteorological condi­tions and tuned for the Black Sea ecosystem in particular. The main advantage of the GETM-BSEM model set-up for the Black Sea is the possibility to study: (i) the long-term evolution of the Black Sea ecosystem; (ii) the effect of nutrient load and regional weather on the biogeochemical structure. Data sets consists of monthly mean values of total phytoplankton (large + small) and nitrate concentrations on a horizontal grid of 423x172 data points (2 longitude minutes x 2 latitude minutes) and 70 vertical levels. Simulations are performed for the period from 1960 to 2014 (55 years). The 3D monthly mean vertical coordinate (m), phytoplankton (mmol N/m**3) and nitrate (mmol N/m**3) are stored in NetCDF format