Sub-ice algal assemblages of the Barents Sea: Species compostion, chemical composition, and growth rates 1986 - 1988

This dataset describes ice algae (10 species; 38 rows) of the Barents Sea studied from 1986 to 1988. With a few exceptions, the ice algal assemblages were dominated by pennate diatoms. From March to early June there was a transition from a mixed population of both centric and pennate diatoms at the start into a well developed Nitzschia frigida assemblage. Nutrients in ice-covered regions were high in spring, and high N/C and protein/carbohydrate ratios indicated no nutrient deficiency in the ice algae. The N/P ratios were lower than 15, but comparable to ratios of three ice algae species grown in culture at -0.5 C and various light conditions. The Si/N ratios were lower than corresponding ratios from the Canadian Arctic and the Anarctic. The chemical composition revealed that silicate limited growth cannot be excluded. The cells were heavily shade-adapted the entire spring season, with high Chl/C ratios (0.045-0.084), comparable to the cultures growing at low irradiances. The growth rates in the cultures peaked at 50 μmol m-2 s-1 with maximum rates of 0.6-0.8 div. day-1, both for 12 and 24 h day lengths. The low growth rates for the May assemblages (max 0.20 div. day-1) indicated strong light limitation by self-shading. Adaptation experiments showed that some ice algae are highly adaptable, while others are not able to adjust by high irradiances, and this may affect the distribution in the field.