Abstract：
Arctic fjords ecosystems are highly dynamic, with organisms exposed to various natural stressors along with productivity clines driven by advection of water masses from shelves. The benthic response to these environmental clines has been extensively studied using traditional, morphology-based approaches mostly focusing on macroinvertebrates. In this study we analyse the effects of glacially mediated disturbance on the biodiversity of benthic macrofauna and meiobenthos (meiofauna and Foraminifera) in a Svalbard fjord by comparing morphology and eDNA metabarcoding. Three genetic markers targeting metazoans (COI), meiofauna (18S V1V2) and Foraminifera (18S 37f) were analyzed. Univariate measures of alpha diversity and multivariate compositional dissimilarities were calculated and tested for similarities in response to environmental gradients using correlation analysis. Our study showed different taxonomic composition of morphological and molecular datasets for both macrofauna and meiobenthos. Some taxonomic groups while abundant in metabarcoding data were almost absent in morphology-based inventory and vice versa. In general, species richness and diversity measures in macrofauna morphological data were higher than in metabarcoding, and similar for the meiofauna. Both methodological approaches showed different patterns of response to the glacially mediated disturbance for the macrofauna and the meiobenthos. Macrofauna showed an evident distinction in taxonomic composition and a dramatic cline in alpha diversity indices between the outer and inner parts of fjord, while the meiobenthos showed a gradual change and more subtle responses to environmental changes along the fjord axis. The two methods can be seen as complementing rather than replacing each other. Morphological approach provides more accurate inventory of larger size species and more reliable quantitative data, while metabarcoding allows identification of inconspicuous taxa that are overlooked in morphology-based studies. As different taxa may show different sensitivities to environmental changes, both methods shall be used to monitor marine biodiversity in Arctic ecosystems and its response to dramatically changing environmental conditions.
摘要：
北极峡湾生态系统是高度动态的，生物体暴露于各种自然压力下，以及由架子上的水团平流驱动的生产力。底栖动物对这些环境的反应已经使用传统的方法进行了广泛的研究，基于形态学的方法主要集中在大型无脊椎动物上。在这项研究中，我们通过比较形态学和eDNA元编码，分析了冰川介导的干扰对斯瓦尔巴特峡湾底栖动物和底栖动物（小动物和有孔虫）生物多样性的影响。针对后生动物（COI）的三个遗传标记，分析了小型动物（18SV1V2）和有孔虫（18S37f）。计算了α多样性和多变量组成差异的单变量度量，并使用相关分析测试了响应环境梯度的相似性。我们的研究显示了大型动物和底栖动物的形态和分子数据集的分类组成不同。在基于形态学的清单中几乎不存在一些分类组，而在元码数据中却很丰富，反之亦然。总的来说,大型动物形态数据中的物种丰富度和多样性度量高于元编码，和类似的meiofauna。两种方法论方法都显示了对大型动物和大型底栖动物的冰川介导的干扰的不同反应模式。大型动物在峡湾的外部和内部之间的分类组成和α多样性指数方面表现出明显的区别，而底栖动物对峡湾轴的环境变化表现出逐渐变化和更微妙的反应。这两种方法可以看作是相互补充而不是相互替换。形态学方法提供了更准确的更大尺寸的物种清单和更可靠的定量数据，而元编码允许识别在基于形态学的研究中被忽视的不显眼的分类单元。由于不同的分类单元可能对环境变化表现出不同的敏感性，这两种方法都应用于监测北极生态系统中的海洋生物多样性及其对急剧变化的环境条件的响应。
