Standing crops of diatoms, measured in terms of chlorophyll a concentration, and measurements of phosphate, silicate and salinity in sea ice are presented. Salinity profiles in the Gulf of St. Lawrence showing highest salinities in the lowest segment of the ice differed from those at the 3 northern stations, in which higher salinities were found at the top and the bottom of the ice, lowest at mid-levels. Nutrient concentrations were similar in all 4 areas. Chlorophyll a concentrations in the lowest segment of the ice, and chlorophyll a concentrations expressed as weight per square meter, were 1-2 orders of numbers higher in the northern stations than in the Gulf of St. Lawrence. Between 96% and 99% of the diatoms at the northern stations were pennate species, mainly benthic forms, whereas only 57% were pennates in the Gulf of St. Lawrence, the remainder being planktonic centric species. |
