brcensus 93jan 18jan93-25jan93 At-sea seabird censuses to determine abundance and distribution in the Palmer LTER marine grid. The files provide general spatial and environmental data associated with both stationary and moving transects, and specific data on the species encountered (including marine mammals), their abundance, distribution and behavior. crxxx93h.dat cruise number, event number, transect start time (GMT), transect start point on LTER grid, transect end point on LTER grid, ship speed (knots), sea state (Beaufort scale), marine habitat type, ice cover (octas), ice type, ice color, crxxx93t.dat cruise number, event number, time of observation (the minute the observation is made), taxa observed, number observed, linkages (feeding associations between species), behavior, notes, crxxx93s.dat cruise number, event number, station number, time (GMT), sea state, marine habitat type, ice cover (octas), ice type, ice color, time of observation (the minute the observation is made), taxa observed, linkages (feeding associations between species), behavior, notes, Stationary censuses, twice at each station; moving censuses, 1-3 between stations. Two types of transects are conducted, moving and stationary. During moving transects (the ship underway at 6 knots or more in open water; 3 knots or more in ice) between stations, seabirds are censused as they enter a 90 degree quadrant off the ship's starboard or port side bow. These censuses also start and end with a stern count of seabirds following the ship. The use of these quarters alternates, depending on what side offers better visibility, but both quarters are never used during the same census. Censuses are confined to seabirds within 300m of the ship and typically last 30 minutes each. In the second type of transect, an instantaneous census lasting 1 minute is made to document all seabirds around the ship when it stops to begin an oceanographic station. This census covers 360 degrees and includes all seabirds within 300m of the ship. After completing this census, another 15 minute census is done that is confined to birds that enter a 90 degree quadrant off the ship's starboard or port-side bow. All censuses also record marine mammals (seals within 300m of the ship an whales within 800m of the ship). The objectives of the LTER seabird component during the 92-93 season cruises were similar. These objectives included 1) determining the pelagic abundance and distribution of Adelie Penguins, 2) examining how the physical and biological characteristics of the marine environment influence these parameters and, 3) using these data to identify foraging areas that may be important to Adelie populations being studied as part of land-based work at Palmer Station. Secondary objectives included documenting the abundance and distribution of other seabirds and marine mammals within the LTER study area. The focus of the January cruise was the nearshore foraging habitat, which required sampling at smaller scales. All seabird censuses were thus conducted within approximately 100 kms of Palmer Station while traversing a sampling grid with stations at 10km intervals. The first two days (18-20 January) of this cruise were spent covering the selected grid as rapidly as possible resulting in 45 transects spaced at 45-60 minute intervals. There were no stops at the 10km stations during this Fast Grid phase. Upon completion of the Fast Grid, a force 12 gale suspended data collection for 24 hours. From January 22-25 the grid direction was reversed and the grid repeated. During this Slow Grid phase, 2-M net tows were done at 10km intervals and BOPS and 1-M and 2-M net tows every 20 km. All seabird censuses during the cruise were done using the procedures outlined in the previous paragraph. Seventy-two 30-minute transects and 15 station censuses were completed during the January cruise. Athough seabirds were widely distributed throughout the study area, the highest densities and greatest biomass occurred consistently within 2-5 km of Anvers Island and several major island groups to the south and west near the Antarctic Peninsula. Adelie Penguins were the dominant component of this seabird assemblage in terms of both abundance and biomass. South Polar Skuas ranked second and Black-browed Albatross third, with the latter becoming the dominant assemblage member at distances greater than 10km from land. Although South Polar Skuas had been expected to occur in more pelagic habitats, few were censused at distances greater than 10km from land. The presence of both skuas and penguins so close to land was unexpected. The most important variable accounting for variation in the distribution and abundance of seabirds appeared to be the location of the 200m contour, which throughout the study area occurred 2-5km from the adjoining land masses. Approximately 65% of the seabirds censused during this cruise (85% of the biomass) occurred in association with this contour. antarctica, adelie penguin, seabirds, biomass, foraging ecology, sea ice, winter ascii local DBASE online LTER ~lter/lterdata/93jan/brcensus/crjan93h ~lter/lterdata/93jan/brcensus/crjan93s ~lter/lterdata/93jan/brcensus/crjan93t William R. Fraser Wayne Z. Trivelpiece William R. Fraser William R. Fraser Wayne Z. Trivelpiece William R. Fraser Donna L. Patterson Nina Karnovsky (Aug cruise only) Douglas Wallace (Aug cruise only) William R. Fraser 12 December 1996 Fraser, W.R. and D.G. Ainley. 1986. Ice edges and seabird occurrence in Antarctica. BioScience 36: 258-263. Ainley, D.G., W.R. Fraser, C.W. Sullivan, J.J. Torres, T.L. Hopkins and W.O. Smith. 1986. Antarctic mesopelagic micronekton: evidence from seabirds that pack ice affects community structure. Science 232: 847-849. Ainley, D.G., W.R. Fraser and K.L. Daly. 1988. Effects of pack ice on micronektonic communities in the Weddell Sea. In, Antarctic Ocean and Resources Variability, D. Sahrhage, ed., Springer-Verlag, Berlin, 140-146. Fraser, W.R., R.L. Pitman and D.G. Ainley. 1989. Seabird and fur seal responses to vertically migrating krill swarms in Antarctica. Polar Biology 10: 37-41. Ainley, D.G., W.R. Fraser, W.O. Smith, T.L. Hopkins and J.J. Torres. 1991. The structure of upper level pelagic food webs in the Antarctic: Effect of phytoplankton distribution. Journal of Marine Systems 2: 111-122. Ribic, C.A., D.G. Ainley and W.R. Fraser. 1991. Habitat selection by marine mammals in the marginal ice zone. Antarctic Science 3: 181-186. Ainley, D.G., C.A. Ribic and W.R. Fraser. 1992. Does prey preference affect habitat choice in Antarctic Seabirds? Marine Ecology Progress Series 90: 207-221. Fraser, W.R., W.Z. Trivelpiece, D.G. Ainley and S.G. Trivelpiece. 1992. Increases in Antarctic penguin populations: reduced competition with whales or a loss of sea ice due to global warming? Polar Biology 11: 525-531. Fraser, W.R., W.Z. Trivelpiece, B. Houston and D.L. Patterson. 1992. Palmer LTER: Seabird research undertaken during 1991-1992 at Palmer Station, Antarctic Peninsula, Antarctic Journal of the Unites States 27: 249-250. Fraser, W.R. and W.Z. Trivelpiece. 1996. Factors controlling the distribution of seabirds: Winter-Summer heterogeneity in the distribution of Adelie Penguin Populations. In, Foundations for Ecological Research West of the Antarctic Peninsula, E. Hofmann, R. Ross and L. Quetin, eds., AGU Antarctic Research Series, Washington, D.C. Key to acronyms and abreviatons used in pal-lter seabird databases. Palmer manual for censusing seabirds at sea. All data are initially recorded in field notebooks. Quality assurance is determined during two subsequent stages. The first is when data are moved from field notebooks to data sheets; the second is when data are moved from data sheets to databases.

Datafile Form V1.2 for describing a data file.