Morphology and Chemical Composition of a Natural Population of an Ice‐associated Antarctic Diatom Navicula Glaciei¹

During winter (1973), a very pure natural population of the diatom Navicula glaciei Van Heurck occurred in dense concentrations (up to 244 mg·m −2 chlorophyll a) in the sea ice at Signy Island, South Orkneys, Antarctica. Samples of algal material were collected for subsequent chemical analysis. The diatom had a composition of 33.77% ash, 21.81% lipid, 25.38% crude, protein, 19.04% crude carbohydrate and an intact calorific value of 15.384 KJ·g −1 . Carbon, hydrogen, nitrogen and phosphorus formed 34, 5.3, 4.1 and 0.52% dry wt respectively. The material was analysed for the trace elements Na, K, Fe, Ca, Mg, Al, Zn, Cu, Pb, Mn, 137 Cs. Fatty acid composition was dominated by 16:0 palmitic acid (20.46%), 16:1 palmitoleic acid (32.86%), and 20:5 docosahexaenoic acid (19.33%). To supplement a very scanty original description, a full taxonomic description is given in the text.