Sea-ice cover across the Arctic has declined rapidly over the past several decades owing to amplified climate warming. The Pacific walrus (Odobenus rosmarus divergens) relies on sea-ice floes in the St. Lawrence Island (SLI) and Wainwright regions of the Bering and Chukchi seas surrounding Alaska as a platform for rest, feeding and reproduction. Lower concentrations of thick ice floes are generally associated with earlier seasonal fragmentation and shorter annual persistence of sea-ice cover, potentially affecting the life history of the Pacific walrus. In this study, 24 Landsat satellite images were classified into thick ice, thin ice or open water to assess sea-ice fragmentation over the spring-summer breakup period. Geospatial fragmentation analyses traditionally used in terrestrial landscapes were newly implemented in this study to characterize the icescape environment. Fragmentation of sea ice was assessed based on the Percent of Landscape, Number of Patches, Mean Area, Shape Index, Euclidean Nearest Neighbor and Edge Density. Results show that lower sea-ice concentrations in both the SLI and Wainwright regions were associated with smaller sea-ice floes. In the Bering Sea, lower sea-ice concentrations were also associated with increases in the number of ice floes, floe isolation and edge density. By contrast, lower sea-ice concentrations in the Chukchi Sea were associated with ice floes that were more circular in shape. The continuation of sea-ice decline with shifting icescape characteristics may result in walruses having to swim longer distances in the northern Bering Sea and adapt to use less-preferred, rounder ice floes in the Chukchi Sea.

由于气候变暖加剧，在过去几十年中，整个北极的海冰覆盖率迅速下降。太平洋海象 ( Odobenus rosmarus 发散) 依靠阿拉斯加周围白令海和楚科奇海的圣劳伦斯岛 (SLI) 和温赖特地区的海冰作为休息、觅食和繁殖的平台。较低浓度的厚浮冰通常与较早的季节性破碎和较短的海冰覆盖年持续时间有关，可能会影响太平洋海象的生活史。在这项研究中，将 24 幅 Landsat 卫星图像分为厚冰、薄冰或开阔水域，以评估春夏季分裂期间的海冰碎裂情况。本研究新实施了传统上用于陆地景观的地理空间碎片分析，以表征冰景环境。根据景观百分比、斑块数量、平均面积、形状指数、欧几里得最近邻和边密度。结果表明，SLI 和温赖特地区较低的海冰浓度与较小的浮冰有关。在白令海，较低的海冰浓度也与浮冰数量、浮冰隔离和边缘密度的增加有关。相比之下，楚科奇海中较低的海冰浓度与形状更圆的浮冰有关。随着冰景特征的变化，海冰的持续减少可能导致海象不得不在白令海北部游得更远，并适应在楚科奇海使用不太受欢迎的较圆的浮冰。较低的海冰浓度也与浮冰数量、浮冰隔离和边缘密度的增加有关。相比之下，楚科奇海中较低的海冰浓度与形状更圆的浮冰有关。随着冰景特征的变化，海冰的持续减少可能导致海象不得不在白令海北部游得更远，并适应在楚科奇海使用不太受欢迎的较圆的浮冰。较低的海冰浓度也与浮冰数量、浮冰隔离和边缘密度的增加有关。相比之下，楚科奇海中较低的海冰浓度与形状更圆的浮冰有关。随着冰景特征的变化，海冰的持续减少可能导致海象不得不在白令海北部游得更远，并适应在楚科奇海使用不太受欢迎的较圆的浮冰。