BACTERIAL BIOMASS, HETEROTROPHIC PRODUCTION AND UTILIZATION OF DISSOLVED ORGANIC-MATTER PHOTOSYNTHETICALLY PRODUCED IN THE ALMERIA-ORAN FRONT

Bacterial biomass, bacterial production and the quantitative importanc e of the heterotrophic assimilation of photosynthetically produced dis solved organic carbon (PDOC) were examined in relation to the hydrodyn amical and biological conditions in the Almeria-Oran front area (Albor an Sea, Western Mediterranean). Although, including all data, bacteria l abundance correlated with chlorophyll a (r = 0.49), the bacteria/ ph ytoplankton carbon ratio decreased in the core of the Atlantic jet. Ba cterial integrated secondary production ranged from 124 to 199 mg C m- 2 d-1. Bacterial generation times averaged 3.2 d (S.D. = 1.3) in front al sites above the pycnocline and 25 d (S.D. = 11) under the pycnoclin e. In the adjacent Mediterranean waters, bacterial generation times di splayed homogenous values from the surface to 150 m (mean 2.7 d; S.D. = 1.5). An isolated Atlantic water mass, at the right side of the jet, showed the longest average bacterial generation times (9.5 d). In the chlorophyll maximum layers, percent extracellular release represented 23.5% of total net primary production in the oligotrophic sites and o nly 6.5% in the core of the Atlantic jct. The contribution of PDOC to bacterial production exhibited large variations (17-100%). Dissimilari ties among sites and hydrodynamical structures of the water masses wer e mostly observed in bacterial generation times and phytoplankton extr acellular release.