Variations of particulate proteins and dissolved amino acids in coastal seawater

The relationships existing between the protein-containing fraction of particulate matter and amino acids dissolved in seawater were studied in the Gulf of Marseille at different periods of the year. The concentration of particulate proteins was almost zero in February and attained maximum values during April and May, the average concentrations of dissolved amino acids (total) varied between 900 and 1200 nmole l^?1 but larger variations were encountered at the surface and in the vicinity of the sediment. The influence of meteorological conditions and the effect of the sediment on the distribution of nitrogenous substances were taken into account. Combined dissolved amino acids were more abundant than free dissolved amino acids in 90% of the cases. The concentrations of dissolved amino acids observed in a zone bordering the North Mediterranean are comparable to those found in other regions of the world.