| ABSTRACT | Three areas of different ecosystem characteristics in the Northern Levantine Basin is compared using a 1-D multicomponent lower trophic level ecosystem model developed by SALIHOĞLU, B. et al. (2009) (NAGEM). Main focus was to analyze and compare the carrying capacity (PP) and regulatory mechanisms of the nutrients on lower trophic levels. 26 years’ of historical data obtained from METU-IMS data inventory and CORIOLIS was used to form a climatology, to introduce boundary conditions to the model as well as to carry out model skill analyses. At the three sites (Erdemli Times Series, that represents a coastal system, Mersin Bay, that represent offshore waters and Rhodes upwelling area) vertical mixing in winter and stratification in summer are found to play a major role in the distribution of nutrients in the water column resulting shift in ecosystem structure. Furthermore, model results suggest distinct mechanisms that control phytoplankton biomass in each region. In Rhodes upwelling area, highest annual primary production values calculated due to nutrient-rich, deep water carried into the euphotic zone throughout the year. On the other hand, the strongest and deepest spring bloom occurred at Erdemli coasts which are attributed to increasing riverine input to the area in early spring. Offshore waters of Mersin Bay have the lowest productivity throughout the year with minor pulses during winter and spring seasons. The model also suggests alterations on limiting nutrients due to changing nutrient budgets among sites. Even though all areas are found to be limited by phosphate, offshore waters of Mersin Bay are also co-limited by nitrogen for autotrophic eukaryotes and diatoms in the summer season. This limitation also occurs in ETS station for diatom species. |