Compiled seabird densities and distance to fronts in the Southern Ocean

We conducted a Southern Ocean seabird data synthesis using previously
collected Antarctic-wide cruise data to determine seabird species
assemblages and quantitative relationships to fronts as a way to provide
context to the long-term Palmer Long Term Ecological Research (LTER)
program and the winter Southern Ocean Global Oceans Ecosystems Dynamics
(GLOBEC) studies in the eastern Bellingshausen Sea. We combined 9 cruises
conducted in areas around the Antarctic continent during the summer
(October-March) for an Antarctic-wide summer data set with 2348 transects
and 63 species seen at least once. We combined seven cruises conducted in
areas around the Antarctic continent during the winter (April-September)
for an Antarctic-wide winter data set with 1591 transects and 56 species
seen at least once. We used 6 Palmer LTER cruises which, combined, had
1446 transects and 29 species seen at least once. The 4 winter Southern
Ocean GLOBEC cruises combined had 652 transects and 16 species seen at
least once. Fronts investigated during both winter (April–September) and
summer (October–March) were the southern boundary of the Antarctic
Circumpolar Current (ACC), which separates the High Antarctic from the Low
Antarctic water mass, and within which are embedded the marginal ice zone
and Antarctic Shelf Break Front; and the Antarctic Polar Front, which
separates the Low Antarctic and the Subantarctic water masses. Using GIS,
distances to the different fronts were measured for all transects and
water mass determined; these variables were added to the seabird density
files for 4 combined density-environmental files (Antarctic-wide-summer,
Antarctic-wide-winter, PALTER-summer, SOGLOBEC-winter).

我们利用既往收集的南极全域航次数据开展南大洋海鸟数据综合分析，旨在明确海鸟物种群落及其与锋面的定量关系，为长期帕尔默长期生态研究（Palmer Long Term Ecological Research, LTER）项目及东别林斯高晋海冬季南大洋全球海洋生态系统动力学（Southern Ocean Global Oceans Ecosystems Dynamics, GLOBEC）研究提供背景支撑。我们整合了南极大陆周边区域夏季（10月-3月）开展的9个航次数据，构建了包含2348条样线、至少观测到63个物种的南极全域夏季数据集；同时整合了该区域冬季（4月-9月）开展的7个航次数据，形成包含1591条样线、至少观测到56个物种的南极全域冬季数据集。此外，我们纳入了6个帕尔默LTER航次数据，合计包含1446条样线及至少29个物种；4个冬季南大洋GLOBEC航次数据合计包含652条样线及至少16个物种。研究针对冬夏两季（冬季：4月-9月，夏季：10月-3月）的锋面展开分析，包括分隔高南极与低南极水团的南极绕极流（Antarctic Circumpolar Current, ACC）南边界（其内部嵌有边缘冰区与南极陆架断裂锋），以及分隔低南极与亚南极水团的南极极锋。借助地理信息系统（GIS），我们测量了所有样线至不同锋面的距离并确定了水团类型；随后将这些变量整合至海鸟密度文件中，形成4个密度-环境综合文件（Antarctic-wide-summer、Antarctic-wide-winter、PALTER-summer、SOGLOBEC-winter）。