Sea ice characteristics were studied in relation to nutrient dynamics, biomass and community structure and composition of ice biota from the Gulf of St. Lawrence at landfast and drifting ice stations in the Magdalen Islands area. The instability of the ice substrate was demonstrated with respect to short duration of cover (8 weeks), ice melt and rafting processes. / The study of nutrient dynamics in ice and in seawater suggests silicates and nitrogen (NO$ sb2$+NO$ sb3$+NH$ sb4$) limitation at landfast ice stations, as well as in situ regeneration of phosphorus in the bottom ice sections. No correlation was found between microalgal biomass and nutrients, but specific growth rates were in the lower range of values reported for Arctic ice algae. / The composition of the microalgal ice biota revealed two types of communities. The first type was composed of a majority of pennate diatoms (abundance $>$ 98%), with dominant species such as Nitzschia cylindrus, N. polaris and Navicula kariana, similar to Arctic landfast ice biota communities. The second type was composed of a high percentage of centric diatoms (abundance $>$ 46%) due to the abundance of the planktonic diatom Thalassiosira norderskioldii. Community structure and composition are discussed with respect to the instability of the ice substrate, and the comparison between landfast and drifting pack ice.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.75939 |
| Date | January 1989 |
| Creators | De Sève, Michèle |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Institute of Oceanography.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 000910072, proquestno: AAINL52377, Theses scanned by UMI/ProQuest. |
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