A Year in Hypoxia: Epibenthic Community Responses to Severe Oxygen Deficit at a Subsea Observatory in a Coastal Inlet
A Year in Hypoxia: Epibenthic Community Responses to Severe Oxygen Deficit at a Subsea Observatory in a Coastal Inlet
复制标题
缺氧一年：表层生物群落对沿海入口海底观测站严重缺氧的反应
作者：
M. Matabos;V. Tunnicliffe;S. Kim Juniper;C. Dean;M. Solan
气候变化导致的海洋通风变化导致公海氧气流失，进而影响东北太平洋等上升流区的沿海地区。加拿大西海岸的萨尼奇湾（Saanich Inlet）是一个天然的季节性缺氧峡湾，某些大陆架物种在极端缺氧的情况下生存。VENUS海底电缆网络的一个研究地点位于104米深的缺氧区。在2009年10月6日至2010年10月18日期间，每2/3天用遥控照相机拍摄相同5 m2区域的照片，并检查群落组成、物种行为和微生物垫特征。位于附近平台上的仪器提供了对环境变量的高分辨率测量。我们采用多元排序方法和主坐标分析的邻居矩阵，以确定我们的数据集的时间结构。对季节性缺氧（0.1-1.27 ml/l）的反应及其在短时间尺度（小时）上的高变异性在物种之间及其生命阶段之间存在差异。在极度缺氧期间，尽管氧气低于0.2毫升/升，微生物垫仍会形成，然后消失，因为一种鲎虾（Spirontocaris sica）以高密度（200 m-2）出现。细长的唯一Lyopsetta exilis是丰富的严重缺氧和减少氧气增加在夏季。这种食虫动物可能对浮游动物昼夜迁徙深度的变化做出反应。虽然蹲龙虾Munida quadrispina是常见的在任何时候，青少年消失在波动的条件。尽管低氧条件下，动物密度很高，表明缺氧的风险是平衡的因素，如食物供应和逃避较不宽容的捕食者。随着大陆架缺氧的增加，我们预计底栖生物群落将由多样性低、耐缺氧、商业价值低的物种主导。
Changes in ocean ventilation driven by climate change result in loss of oxygen in the open ocean that, in turn, affects coastal areas in upwelling zones such as the northeast Pacific. Saanich Inlet, on the west coast of Canada, is a natural seasonally hypoxic fjord where certain continental shelf species occur in extreme hypoxia. One study site on the VENUS cabled subsea network is located in the hypoxic zone at 104 m depth. Photographs of the same 5 m2 area were taken with a remotely-controlled still camera every 2/3 days between October 6th 2009 and October 18th 2010 and examined for community composition, species behaviour and microbial mat features. Instruments located on a near-by platform provided high-resolution measurements of environmental variables. We applied multivariate ordination methods and a principal coordinate analysis of neighbour matrices to determine temporal structures in our dataset. Responses to seasonal hypoxia (0.1–1.27 ml/l) and its high variability on short time-scale (hours) varied among species, and their life stages. During extreme hypoxia, microbial mats developed then disappeared as a hippolytid shrimp, Spirontocaris sica, appeared in high densities (200 m−2) despite oxygen below 0.2 ml/l. The slender sole Lyopsetta exilis was abundant in severe hypoxia and diminished as oxygen increased in the summer. This planktivore may be responding to changes in the depth of the diurnal migration of zooplankton. While the squat lobster Munida quadrispina was common at all times, juveniles disappeared in fluctuating conditions. Despite low oxygen conditions, animal densities were high indicating that the risk from hypoxia is balanced by factors such as food availability and escape from less tolerant predators. As hypoxia increases on the continental shelf, we expect benthic communities to become dominated by low diversity, hypoxia-tolerant species of low commercial significance.