Simulations of biological production in the Rhodes and Ionian basins of the eastern Mediterranean

The biological production characteristics of the Rhodes and western Ionian basins of the eastern Mediterranean are studied by a one-dimensional, coupl ed physical-biological model. Tbe biological model involves single aggregat ed compartments of phytoplankton, zooplankton, detritus as well as ammonium and nitrate forms of the inorganic nitrogen. It interacts with the physica l model through the vertical eddy diffusivity which is calculated using the Mellor-Yamada level 2.5 turbulence parameterization. The model simulations demonstrate the importance of the contrasting physical oceanographic chara cteristics of these two basins on affecting their yearly planktonic structu res. The annual primary production in the Rhodes basin is estimated as simi lar to 97 g C m(2) yr(-1) which is comparable with the northwestern Mediter ranean. The western Ionian basin, on the contrary, possesses only 10% of th e Rhodes' productivity and therefore represent a most oligotrophic site in the eastern Mediterranean. The Rhodes basin reveals a strong bloom in early spring, typically in March, a weaker bloom in early winter, typically in J anuary, and a subsurface production below the seasonal thermocline during s ummer. This structure is slightly modified in the western Ionian basin, and the early winter and early spring blooms are merged to cover the entire wi nter. These results are supported favorably by the available observations b oth in their magnitudes and timing. (C) 2000 Elsevier Science B.V. All righ ts reserved.