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Ducklow, HW, Fraser W, Karl DM, Quetin LB, Ross RM, Smith RC, Stammerjohn SE, Vernet M, Daniels RM.  2006.  Water-column processes in the West Antarctic Peninsula and the Ross Sea: Interannual variations and foodweb structure. Deep-Sea Research Part Ii-Topical Studies in Oceanography. 53:834-852.   10.1016/j.dsr2.2006.02.009   AbstractWebsite

The sea-ice zone of the Antarctic exhibits high rates of primary productivity and large interannual variability in plankton and biogeochemical properties, influenced by variations in the timing, extent and duration of sea-ice advance and retreat. In the past decade several interdisciplinary research programs conducted investigations in the sea ice zones of the West Antarctic Peninsula (WAP) and Ross Sea. In this article we synthesize results of these investigations to provide an overview of water-column processes influenced by regional-scale sea-ice dynamics. Primary production (PP) off the WAP varies by nearly an order of magnitude from year-to-year, and its interannual variability is related to the amount of open water within the annual ice pack. The annual sedimentation at 170 m averages about 2% of the overlying PP but is not related to interannual variations in the ice or PP. Rather the interannual variations in sedimentation are related to stocks of krill and salps. Plankton foodwebs in the Ross Sea and WAP exhibit similar annual PP but differ greatly in quantitative foodweb structure. Foodwebs of the WAP are dominated by krill grazing of spring-summer diatom blooms, whereas in the Ross Sea the extensive and early (November) bloom of Phaeocystis antarctica is not grazed and similar to 50% sinks as ungrazed cells. Foodweb reconstructions from inverse models suggest that some functional characteristics of foodwebs in the two regions are quite similar in spite of taxonomic contrasts. Relatively high rates of microbial processing and nutrient recycling characterize both systems, even during years in the WAP when PP differs by an order of magnitude. These similarities indicate broad functional similarities across contrasting foodweb composition in the sea-ice zone. (c) 2006 Elsevier Ltd. All rights reserved.

Martinson, DG, Stammerjohn SE, Iannuzzi RA, Smith RC, Vernet M.  2008.  Western Antarctic Peninsula physical oceanography and spatio-temporal variability. Deep-Sea Research Part Ii-Topical Studies in Oceanography. 55:1964-1987.   10.1016/j.dsr2.2008.04.038   AbstractWebsite

This study focuses on 12 years of physical oceanography data, collected during the Palmer, Antarctica, Long-Term Ecological Research program (PAL LTER) over the continental margin of the western Antarctic Peninsula (WAP). The dataset offers the most long-lived consistent CTD-gridded observations of Antarctic waters collected anywhere in the Southern Ocean. The physical characteristics, water column structure and spatio-temporal variability of the various properties are examined for physically consistent and ecologically important patterns and modes of variability. Unique findings of note include: (1) The average annual ocean heat flux (to the atmosphere) over the continental shelf shows a decreasing trend through time averaging 0.6 W m(-2) yr(-1), with an annual average ocean heat flux of similar to 19W m(-2). The ocean heat content over the shelf shows a linearly increasing trend of 2.6 x 10(7) J m(-2) yr(-1), due predominantly to increased upwelling of warm Upper Circumpolar Deep Water (UCDW) onto the shelf with a small contribution due to a slight warming of UCDW (but over longer time scales (50yr), the warming of UCDW dominates), (2) optimal multi-annual average vertical turbulent diffusivity coefficient (k(z)) is similar to 8.5 x 10(-5) m(2)s(-1), determined by inversion considering warming of trapped remnant winter mixed layer water, (3) the water masses in the grid are well separated according to bathymetrically controlled features, dividing the sample domain into 3 sub-regions: slope, shelf and coastal waters; (4) the Antarctic Circumpolar Current (ACC) was always present along the shelf-break (consistent with the Orsi et al. [1995. On the mericlional extent and fronts of the Antarctic Circumpolar Current. Deep-Sea Research 1 42 (5), 641-673.] climatology) where UCDW shows its farthest southern extent and forms the Southern ACC Front (SACCF). The spatio-temporal variability of the delivery and distribution of ocean heat is dictated by the dynamics that are consistent with changes in the state of ENSO (La Nina drives enhanced upwelling in this region) and in the strength of the Southern Annular Mode (SAM; +SAM drives a local response similar to that of La Nina). The large 1997-1998 El Nino, followed by the transition to the strong La Nina of 1998-1999 (amplified by a large +SAM) introduced a regime shift on the shelf, resulting in the elimination of similar to 0.5 m of sea ice melt (presumably from the loss of sea ice being grown). 2002 was an anomalous year coinciding with an extraordinary storm forcing driving a 4.5 sigma increase in the heat content on the shelf. These jumps coincide with considerable changes in sea ice distribution as well. Pure UCDW on the shelf is primarily restricted to the deep canyons, with occasional appearances on the shelf floor near the middle of the grid. Anomalies in summer sea surface temperatures reflect wind strength (stronger winds mixing more cold winter water to the surface, with cooler SST; light winds, the opposite). (C) 2008 Elsevier Ltd. All rights reserved.