FATTY-ACID COMPOSITION OF ULVA-PERTUSA KJELLMAN (CHLOROPHYTA) AND GRACILARIA-INCURVATA OKAMURA (RHODOPHYTA) IN JAPANESE COASTAL WATERS

Crude lipid content and total fatty acid composition of 2 macrophytes, Ulva pertusa Kjellman (Chlorophyta) and Gracilaria incurvata Okamura (Rhodophyta) were monitored using material from the wild from March to July 1992. Ulva pertusa contained high levels of C16 (16: 4 n - 3) an d C18 (18: 1, 18: 2n - 6, 18: 3n - 3 and 18: 4n - 3) unsaturated fatty acids (36 - 54% of total fatty acids), while the only unsaturated fat ty acid occurring at high levels in G. incurvata was arachidonic acid (20: 4, 26 - 46% of total fatty acids). Both seaweeds contained high l evels of palmitic acid (16: 0, 19 - 33%). Temperature and daylength we re not regarded as completely distinct environmental factors because o f their highly significant correlation during the period of study (r2 = 0.91, p < 0.003). In U. pertusa, daylength was negatively correlated with crude lipid content (as % dry weight; r2 = 0.96, p < 0.0001), to tal unsaturated fatty acids (r2 = 0.62, p < 0.021) and docosahexaenoic acid (22: 6n - 3; r2 = 0.94, p < 0.0001); while temperature was negat ively correlated with both crude lipid content (as % dry weight; r2 = 0.74, p < 0.006) and 22: 6n - 3 (r2 = 0.74, p < 0.006). Crude lipid co ntent and fatty acid composition of G. incurvata were unrelated to sea sonal changes in temperature and daylength.