The Seasonal Variation of the Free and Combined Dissolved Amino Acids in the Irish Sea

Abstract

Dissolved amino acids, in both the free state and combined as polypeptides, play an important part in the marine biochemistry of nitrogen. These compounds are excreted by phytoplankton (Fogg, 1962, 1966; Stewart, 1963; Hellebust, 1965) and zooplankton (Johannes & Webb, 1965; Webb & Johannes, 1965) and are utilized by algae (Syrett, 1962), bacteria (Proom & Woiwood, 1949) and marine invertebrates (Stephens & Schinske, 1961). Experiments with cultures have shown, indeed, that some species of phyto-plankton will not grow, or grow only with difficulty, if certain amino acids are absent (Harvey, 1938; Provasoli & Gold, 1957; Droop, 1957, 1959, 1962). In addition to their direct biochemical role, amino acids may also serve to complex trace metals, such as copper and iron, and keep them readily available for assimilation by marine organisms (Harvey, 1938; Fogg, 1959; Provasoli, 1963; Kent & Hooper, 1965; Saunders, 1957).