Growth and lipid composition of high Arctic ice algae during the spring bloom at Resolute, Northwest Territories, Canada

Abstract

The concentration and composition of particulate organic matter, with special reference to lipids, was measured throughout the spring bloom of bottom Ice algae in 1989 at a site in the Canadian high Arct~c.By con?paring areas of differing snow cover, and thus light history, we showed that light was initially limiting to algal production.Where snow cover was relatively thin (0 to 5 cm), hght apparently ceased to be limiting to biomass accumulation in the ice as the bloom neared its peak.Compositional ratios, such as C : chlorophyll a and C:N, were consistent with a physiological response of the algae to light-sufficient and, possibly, nutrient-limited conditions following the peak of the bloom.The transition from early to late bloom conditions was accompanied by a shift in lipid composition, from a predominance of polar lipids (glycolipids and phospholipids) and pigments to a predomnance of neutral lipids (tnacylglycerols and free fatty acids).Neutral lip~ds varied directly, as a proportion of total lipid, with the light available to the algae under the different snow covers.Simdar changes of lipid con?position were only partially reproduced in a short-term ( S 2 wk) manipulation of light availability to the natural communities, however, indicating that factors other than the immediate availability of light were important to Lipid synthesis by the ice algae.