Underway and bottle oxygen data collected on the Sikuliaq Research Vessel, Bering and Chukchi Seas, Alaska, 2017

The data archived here were collected during a 2017 research cruise on the Research Vessel Sikuliaq (SKQ201712S). Data were collected between August 2, 2017 and August 22, 2017 between Seward, Alaska (AK) and the Northeast Chukchi Sea. CTD stations were occupied throughout the NE Chukchi and Western Beaufort. We occupied some Distributed Biological Observatory (DBO) stations as part of this work, including DBO4 and DBO5. Satellite measurements have documented significant reductions in sea ice cover, thickness, and duration throughout the Arctic Ocean in recent decades. Because of the complex interactions and feedbacks among physical, biogeochemical and ecological processes in the Arctic, there is significant uncertainty regarding how these changes in sea ice will impact the marine biological pump, which fuels the rich bottom communities on Arctic ocean shelves and is key to the regional carbon cycle. While responses of the biological pump to increased light availability in spring are currently being pursued, a considerable gap in knowledge exists regarding biological processes in the late summer and early fall. Recent studies indicate a several-decade trend of intensifying wind forcing over the Alaskan margin along the Chukchi and Beaufort Seas in the late, ice-free season (September-November). These events could lead to mixing of nutrients into surface waters, fueling increased biological production and sequestering additional carbon into shelf bottom waters prior to the winter ice advance. However, the lack of direct, concurrent observations of primary and net community productivity rates, and nutrient and carbon distributions during this poorly-sampled time of year hinders efforts to assess the ecosystem implications of such changes. The goal of this project was to address the question of increasing biological production in the late season through intensive field sampling in two successive years.

本存档数据集采集自2017年“锡利库阿克号”（Research Vessel Sikuliaq）科考航次（航次编号SKQ201712S），数据采集时段为2017年8月2日至8月22日，采样区域覆盖阿拉斯加州苏厄德（Seward, AK）至楚科奇海东北部海域。本航次在楚科奇海东北部与波弗特海西部全域布设了温盐深（CTD）观测站位，并将部分分布式生物观测（Distributed Biological Observatory, DBO）站位纳入本次科考工作，其中包括DBO4与DBO5站位。近数十年来，卫星观测已证实北冰洋全域海冰覆盖范围、厚度与存续时长均出现显著缩减。由于北极海域物理、生物地球化学与生态过程间存在复杂的相互作用与反馈机制，目前学界对海冰变化将如何影响海洋生物泵（marine biological pump）仍存在显著认知不确定性——海洋生物泵支撑着北极大陆架丰富的底栖生物群落，同时也是区域碳循环的关键环节。尽管当前学界正聚焦春季光照增强对生物泵的影响机制，但针对夏末至初秋的海洋生物过程的研究仍存在大量认知空白。近期研究显示，近数十年来楚科奇海与波弗特海沿线阿拉斯加陆架区在晚季无冰期（9月至11月）的风强迫作用呈持续增强趋势。此类强风事件可促使营养盐向上混合至表层水体，推动生物生产活动增强，并在冬季海冰封冻前将更多碳封存至大陆架底层水体中。然而，由于该采样匮乏时段缺乏针对初级生产力、净群落生产力速率以及营养盐与碳分布的同步直接观测，学界难以评估此类变化对生态系统的潜在影响。本项目旨在通过连续两年的密集野外采样，解答晚季海域生物生产活动增强这一科学问题。