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Polar regions are covered by extensive sea ice that is inhabited by a variety of plants and animals. The environments where the organisms live vary depending on the structure and age of the ice. Many terms have been used to describe the habitats and the organisms. We here characterize the habitats and communities and suggest some standard terms for them. We also suggest routine sampling methods and reporting units for measurements of biological and chemical variables. © 1992 Springer-Verlag GmbH & Co. KG.

The sea ice does not only determine the ecology of ice biota, but it also influences the pelagic systems under the ice cover and at ice edges. In this paper, new estimates of Arctic and Antarctic production of biogenic carbon are derived, and differences as well as similarities between the two oceans are examined. In ice-covered seas, high algal concentrations (blooms) occur in association with several types of conditions. Blooms often lead to high sedimentation of intact cells and faecal pellets. In addition to ice-related blooms, there is progressive accumulation of organic matter in Arctic multi-year ice, whose fate may potentially be similar to that of blooms. A fraction of the carbon fixed by microalgae that grow in sea ice or in relation to it is exported out of the production zone. This includes particulate material sinking out of the euphotic zone, and also material passed on to the food web. Pathways through which ice algal production does reach various components of the pelagic and benthic food webs, and through them such top predators as marine mammals and birds, are discussed. Concerning global climate change and biogeochemical fluxes of carbon, not all export pathways from the euphotic zone result in the sequestration of carbon for periods of hundreds of years or more. This is because various processes, that take place in both the ice and the water column, contribute to mineralize organic carbon into CO2 before it becomes sequestered. Processes that favour the production and accumulation of biogenic carbon as well as its export to deep waters and sequestration are discussed, together with those that influence mineralization in the upper ice-covered ocean. © 1992 Springer-Verlag GmbH & Co. KG.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.dsr.2005.07.001 Byline: Z.-P. Mei (a), L. Legendre (a), J.-E. Tremblay (b), L.A. Miller (c), Y. Gratton (d), C. Lovejoy (a), P.L. Yager (e), M. Gosselin (f) Keywords: Phytoplankton bloom; Stoichiometry; C:N; DIC; NO.sub.3; Biogeochemical cycling Abstract: The carbon to nitrogen (C:N) stoichiometry of phytoplankton production varied significantly during the spring-summer bloom in the North Water Polynya (NOW), from April through July 1998. The molar ratio of particulate organic carbon (POC) to nitrogen (PON) production by phytoplankton ([DELTA]POC:[DELTA]PON) increased from 5.8 during April through early June to 8.9 in late June and July. The molar dissolved inorganic carbon (DIC) to nitrate+nitrite (NO.sub.3) drawdown ratio ([DELTA]DIC: [DELTA]NO.sub.3) increased from 6.7 in April and May, to 11.9 in June (no estimate for July because of ice melting). The discrepancy between [DELTA]POC:[DELTA]PON and [DELTA]DIC:[DELTA]NO.sub.3 was likely due to dissolved organic carbon (DOC) production. Increased [DELTA]POC:[DELTA]PON of phytoplankton and surface water [DELTA]DIC:[DELTA]NO.sub.3 throughout the phytoplankton blooms resulted from changes in physical properties of the upper water column, such as reduced thickness of the surface mixed layer that exposed phytoplankton to increased photosynthetically available radiation (PAR), accompanied by NO.sub.3 depletion. This is expected to have significant effects on the cycling of carbon (C) and nitrogen (N) in pelagic ecosystems, as the increased C:N ratio of organic matter decreases its quality as substrate for grazers and microbial communities. Based on [DELTA]POC:[DELTA]PON, the ratio of POC to chlorophyll a (Chl) production ([DELTA]POC:[DELTA]Chl) and the relationship between Chl yields and NO.sub.3 depletion, we estimate that 71[+ or -]17% and 46[+ or -]20% of the depleted NO.sub.3 went to PON production in the euphotic zone over the polynya from April to early June, and late June to July, respectively. The remaining NO.sub.3 was likely channelled to dissolved organic nitrogen (DON) and heterotrophic bacteria, which were not returned to the dissolved inorganic nitrogen (DIN) pool through recycling during the course of the study. Hence, the autotrophic production of organic N and its recycling by the microbial food web were not coupled temporally. Author Affiliation: (a) Quebec-Ocean, Pavillon Vachon, Universite Laval, Sainte-Foy, Canada QC G1K 7P4 (b) Universite Laval, Departement de Biologie, Quebec, Canada QC G1K 7P4 (c) Centre for Ocean Climate Chemistry, Institute of Ocean Sciences, P.O. Box 6000, Sidney, Canada BC V8L 4B2 (d) INRS-ETE (Eau, Terre, Environnement), 2800 rue Einstein, C.P. 7500, Sainte-Foy, Canada QC G1V 4C7 (e) University of Georgia, School of Marine Programs, 220 Marine Sciences Building, Athens, GA 30602-3636, USA (f) Institut des sciences de la mer de Rimouski (ISMER), Universite du Quebec a Rimouski, 310 Allee des Ursulines, Rimouski, Canada QC G5L 3A1

The examination of velocity fields in currents under land-fast ice in the Canadian Arctic Archipelago using acoustic Doppler current profiler (ADCP) confirms the mixing in three conductivity, temperature and depth profiles, and in acoustic backscatter amplitude. These density inversions exhibit an association with the passage of high frequency linear internal waves and finite amplitude waves. Contours of Richardson number are calculated using density profiles and ADCP velocities, and the conditions are suitable for mixing during the passage of internal waves. The instability is significant above and below the pycnocline.