Isoscape Models of the Southern Ocean: Predicting Spatial and Temporal Variability in Carbon and Nitrogen Isotope Compositions of Particulate Organic Matter
Isoscape Models of the Southern Ocean: Predicting Spatial and Temporal Variability in Carbon and Nitrogen Isotope Compositions of Particulate Organic Matter
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DOI：
10.1029/2020gb006901
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发表时间：
2021-09-01
影响因子：
5.2
通讯作者：
Trueman, Clive N.
中科院分区：
文献类型：
--
作者：
Glew, Katie St John;Espinasse, Boris;Trueman, Clive N.
极地海洋生态系统特别容易受到气候变化的影响。气温升高、海水变淡、海冰形成受到破坏，这些都有可能对食物链产生连锁影响。需要新的方法来更好地了解南大洋食物网基础上的生物地球化学过程之间的时空相互作用。在海洋系统中，碳和氮的等位线(稳定同位素组成的空间变化模型)已被证明有助于确定一系列生物地球化学过程的空间变化，例如浮游植物对营养的利用。在运动、迁徙和饮食研究中，等位线为解释高营养级别动物的稳定同位素组成提供了基线。在这里，我们使用过去50年收集的表层颗粒有机物同位素数据，生成了整个南大洋(>；40度S)的碳和氮等温线。我们使用一组环境数据作为预测变量，使用基于积分嵌套拉普拉斯近似的方法来预测平均年等深线和四个季节等深线。在整个南大洋预测了C-13和N-15增量值的明显空间梯度，这与该区域以前关于同位素变异性的统计和机制观点一致。我们在碳和氮等值线中都发现了强烈的季节变异性，这对在动物研究中使用静态或年平均等值线基线试图记录季节性迁徙或觅食行为具有关键意义。
Polar marine ecosystems are particularly vulnerable to the effects of climate change. Warming temperatures, freshening seawater, and disruption to sea-ice formation potentially all have cascading effects on food webs. New approaches are needed to better understand spatiotemporal interactions among biogeochemical processes at the base of Southern Ocean food webs. In marine systems, isoscapes (models of the spatial variation in the stable isotopic composition) of carbon and nitrogen have proven useful in identifying spatial variation in a range of biogeochemical processes, such as nutrient utilization by phytoplankton. Isoscapes provide a baseline for interpreting stable isotope compositions of higher trophic level animals in movement, migration, and diet research. Here, we produce carbon and nitrogen isoscapes across the entire Southern Ocean (>40 degrees S) using surface particulate organic matter isotope data, collected over the past 50 years. We use Integrated Nested Laplace Approximation-based approaches to predict mean annual isoscapes and four seasonal isoscapes using a suite of environmental data as predictor variables. Clear spatial gradients in delta C-13 and delta N-15 values were predicted across the Southern Ocean, consistent with previous statistical and mechanistic views of isotopic variability in this region. We identify strong seasonal variability in both carbon and nitrogen isoscapes, with key implications for the use of static or annual average isoscape baselines in animal studies attempting to document seasonal migratory or foraging behaviors.