No description available.

No description available.

A multidisciplinary western Beaufort Sea Ecological Cruise (WEBSEC) was conducted from August 15 to September 20, 1971. During the cruise, one hundred ninety-nine 0.1 m² Smith-McIntyre grabs samples were taken at forty stations located on the continental shelf and slope of the western Beaufort Sea. The Gammaridean Amphipoda and Cumacea collected were sorted and identified. Each sample was analyzed for the number of species and specimens within those groups. The data for all samples at each station were pooled to obtain station data; these were analyzed for abundance, diversity at each station, and similarity between stations. Environmental parameters including sediment data, temperature, salinity and organic carbon content measured during the same cruise were also analyzed for each station. The diversity indices chosen were the Simpson index (SDI) and the Shannon-Wiener index (H'[subscript e]). The results obtained show a e relatively high diversity and animal density in the outer continental shelf, but low diversity values on the inner continental shelf and slope. The lowest SDI value obtained is 0.43 at 2572 m depth. The SDI values on the outer continental shelf are higher than 0.9 and compare well with values obtained in more temperate regions. The similarity between stations is low, and the percentage of rare species found is high. This indicates a patchy distribution of the Amphipoda and Cumacea fauna. The variability of the processes affecting the benthic environment of the western Beaufort Sea suggest that more intensive and seasonal studies are necessary in order to understand the seasonal as well as the annual variation of the infauna of the western Beaufort Sea. / Graduation date: 1976

Thesis (M.S. in Meteorology and Physical Oceanography)--Naval Postgraduate School, December 2009. / Thesis Advisor(s): Radko, Timour. Second Reader: Schoenstadt, Arthur. "December 2009." Description based on title screen as viewed on February 01, 2010. Author(s) subject terms: Double diffusion, inverse model, 4/3 Flux Law. Includes bibliographical references (p. 69-71). Also available in print.

Sea ice drift and associated forcing mechanisms within the Beaufort Sea are examined within the context of a mechanically weakening Arctic ice pack. Extensive in situ observations of ice drift, ice mass balance and surface winds are supplemented by remotely sensed and modeled data to analyse the forcing of sea ice motion. First we analyse the anomalous export of 13.4 x 103 km2 of sea ice through the Bering Strait during winter 2011-2012. The event highlights a tendency towards increased ice transport through the Bering Strait since 2008 as a result of climate induced weakening of the arctic ice pack. Secondly, as part of the Beaufort Regional Environmental Assessment we analyse the seasonal evolution of ice drift in the Beaufort Sea during Spring as the ice pack transitions from mechanically strong conditions in late winter to weak summer conditions that foster free drift and thus increased ice drift speeds.

No description available.

No description available.

Les observations dérivées d’images satellites suggèrent que la réduction récente de l’étendue de la glace de mer a entraîné une augmentation de la production primaire en Arctique. Cependant, peu d’observations in situ sont disponibles pour confirmer ces estimations, en particulier au début de la saison de production. Les cellules de microalgues collectées dans des pièges à particules déployés sur trois sites de la mer de Beaufort au cours de trois à cinq cycles annuels de 2011 à 2017 ont été énumérées et identifiées afin d'étudier les changements dans le timing, l'abondance et la composition de l’export de microalgues en relation avec les variations dans le couvert de neige et de glace de mer. Les diatomées ont dominé les flux de microalgues avec différents assemblages au printemps-été (avril à août; Fragilariopsis spp. et Thalassiosira spp.) et à l'automne (septembre-novembre; Cylindrotheca closterium). La fonte des neiges ou la débâcle des glaces s'est produite dès la fin avril (2016) et jusqu'à la mi-août (2013). Les flux printemps-été des diatomées variaient de 0,05 à 500 mg C m⁻² (< 10⁵ à 1,25 x 10¹⁰ cellules m⁻²) et étaient négativement corrélés à la date de la fonte des neiges (r² = 0,35, n = 12) et à la débâcle des glaces (r² = 0,32, n = 12). L’exportation de l’algue de glace Nitzschia frigida reflète la libération des algues de glace au début de la fonte des neiges. Les flux maximaux de diatomées ont été systématiquement observés peu de temps après la débâcle des glaces. La contribution en pourcentage du flux de carbone associé aux microalgues (MC) au flux de carbone organique particulaire (POC) augmente avec l'ampleur du flux de diatomées. L'ampleur du flux de diatomées automnal relativement faible n'était pas corrélée de manière significative à la date de formation du couvert de glace (r² = 0,24, n = 10). Nos résultats sont généralement cohérents avec les observations satellitaires suggérant une augmentation de la biomasse de microalgues et le développement d’une prolifération de diatomées à l’automne en réponse à une saison libre plus longue dans les mers arctiques. Les variations à l’échelle régionale dans le régime de neige et de glace de mer ont une incidence directe sur le moment et l’ampleur de la production de microalgues et sur sa contribution à l’export de POC dans la mer de Beaufort. Avec le réchauffement climatique, la réduction continue du couvert de neige et de glace dans les mers arctiques entraînera une augmentation des flux de carbone vers le benthos et, potentiellement, une séquestration du carbone en profondeur. / Microalgal cells collected in sediment traps deployed at three sites in the Beaufort Sea during three to five annual cycles from 2011 to 2017 were enumerated and identified to investigate changes in the timing, abundance and composition of microalgal export in relation to variations in snow and sea ice cover. Diatoms dominated the microalgal fluxes with different assemblages in spring-summer (April to August; Fragilariopsis spp. and Thalassiosira spp.) and autumn (September-November; Cylindrotheca closterium). Snowmelt or ice breakup occurred as early as late April (2016) and as late as mid-August (2013). The magnitude of the spring-summer diatom flux varied from ~0.05 to 500 mg C m⁻² (< 10⁵ to 1.25 x 10¹⁰ cells m⁻²) and was negatively correlated to snowmelt date (r² = 0.35, n = 12) and sea-ice breakup date (r² = 0.32, n = 12). The export of the ice-obligated algae Nitzschia frigida reflected the release of sea ice algae at the onset of snowmelt. Peak diatom fluxes were consistently observed shortly after seaice break-up. The percent contribution of microalgal carbon to the particulate organic carbon (POC) flux increased with the magnitude of the diatom flux. The magnitude of the relatively small autumnal diatom flux was not significantly correlated to freeze-up date (r² = 0.24, n = 10). Our results are generally consistent with satellite observations suggesting an increase in microalgal biomass and the development of an autumn diatom bloom in response to a longer ice-free season in Arctic seas. Variations at the regional scale in the snow and sea-ice regimes directly impact the timing and magnitude of microalgal production and its contribution to POC export in the Beaufort Sea. With global warming, the ongoing reduction of the sea-ice cover in Arctic seas will result in increased carbon fluxes to the benthos and, potentially, carbon sequestration at depth.

Isopoda are crustaceans which possess seven pairs of legs of about equal size, are flattened dorsoventrally and have no carapace. The thoracic limbs are without exopodites, pleopods are modified for respiration and the antennual exopodite is absent or minute. The isopods are a large group and exhibit much variety. They vary in size from two or three millimeters to several centimeters. A giant deep-sea form, Bathynomus giganteus, from the Gulf of Mexico and Indian Ocean, attains a length of 30 cm. and width of about 10 cc. The natural habitat of isopods is in salt and fresh water or in moist situations in the case of most terrestrial forms. They have been found in warm springs and subterranean streams (Richardson, 1905). [...]

Original print version missing pages 130-133 (appendix B and Appendix C)