Chlorophyll a distribution in the romanian blaCk sea inner shelf waters in 2009

In 2009, seasonal and spatial variability of surface chlorophyll a in Romanian inner shelf waters was studied on the basis of samples collected during four seasonal cruises conducted both in the Danube mouths and Constanta areas. The seasonal distribution showed three peaks; the first one was recorded in February (6.22 ± 2.63 μg/l), followed by a more pronounced one in early May (9.47 ± 6.88 μg/l) corresponding to the Danube’s higher discharges in spring. After a relatively low chlorophyll a in July, there was found the third peak in September (10.29 ± 8.18 μg/l) as a result of a strong diatoms bloom in the Portita area (south of the Danube mouths). Except for winter, the spatial distribution of surface chlorophyll a was characterized by high variability; the chlorophyll a concentrations measured in the Danube mouths area, especially in shallower stations along the Portita profile (> 20 μg/l in May and September), were much higher than those recorded on transect East-Constanta.