EFFECTS OF TEMPERATURE, LIGHT-INTENSITY, SALINITY AND SOURCE OF NITROGEN ON THE GROWTH, TOTAL LIPID AND FATTY-ACID COMPOSITION OF ULVA-PERTUSA KJELLMAN (CHLOROPHYTA)

Growth, total lipid content and fatty acid composition of Ulva pertusa Kjellman were studied in a 4 x 2 factorial laboratory experiment at t wo levels (low and high) of temperature (15 and 25-degrees-C), subsatu rating light intensities (16 - 32 and 48 - 64 muE m-2 s-1), salinity ( 20 and 359 parts per thousand) and two sources of nitrogen (nitrate an d ammonia). Specific growth rate (SGR) was highest at low temperature (15-degrees-C), high light intensity (48 - 64 muE m-2 s-1) and high sa linity (35 parts per thousand). Interaction between temperature, light intensity and nitrogen source was the highest source of variation in SGR at the beginning of culture, while salinity and salinity-light int ensity interactions were the most limiting factors during the later pa rt of culture. Effect of nitrogen source (with a preference for ammoni a) was significant only during the early part of culture. Moisture con tent was increased at low light intensity. Total lipid content (both a s percent of fresh and dry weights) increased at low temperature and h igh salinity. Low temperature increased levels (as % of total fatty ac ids) of oleic (18 : 1n-9) and linolenic (18 : 3n-3) fatty acids. High light intensity increased levels of palmitic acid (16 : 0), the most a bundant fatty acid. Low light intensity (16 - 32 muE m-2 s-1) increase d levels of the tetra-unsaturated fatty acids 16 : 4n-3 and 18 : 4n-3. High salinity increased the levels of the C16 and C18 poly-unsaturate d fatty acids.