Data from: The structure and distribution of benthic communities on a shallow seamount (Cobb Seamount, Northeast Pacific Ocean)

Partially owing to their isolation and remote distribution, research on seamounts is still in its infancy, with few comprehensive datasets and empirical evidence supporting or refuting prevailing ecological paradigms. As anthropogenic activity in the high seas increases, so does the need for better understanding of seamount ecosystems and factors that influence the distribution of sensitive benthic communities. This study used quantitative community analyses to detail the structure, diversity, and distribution of benthic mega-epifauna communities on Cobb Seamount, a shallow seamount in the Northeast Pacific Ocean. Underwater vehicles were used to visually survey the benthos and seafloor in ~1600 images (~5 m2 in size) between 34 and 1154 m depth. The analyses of 74 taxa from 11 phyla resulted in the identification of nine communities. Each community was typified by taxa considered to provide biological structure and/or be a primary producer. The majority of the community-defining taxa were either cold-water corals, sponges, or algae. Communities were generally distributed as bands encircling the seamount, and depth was consistently shown to be the strongest environmental proxy of the community-structuring processes. The remaining variability in community structure was partially explained by substrate type, rugosity, and slope. The study used environmental metrics, derived from ship-based multibeam bathymetry, to model the distribution of communities on the seamount. This model was successfully applied to map the distribution of communities on a 220 km2 region of Cobb Seamount. The results of the study support the paradigms that seamounts are diversity 'hotspots', that the majority of seamount communities are at risk to disturbance from bottom fishing, and that seamounts are refugia for biota, while refuting the idea that seamounts have high endemism.由于海山（seamount）本身的孤立性与分布偏远性，相关研究仍处于起步阶段，目前鲜有全面的数据集与实证证据能够佐证或驳斥主流生态学范式。随着公海人类活动日益频繁，人们亟需更深入地认知海山生态系统，以及影响敏感底栖（benthic）群落分布的各类因素。本研究采用定量群落分析方法，详细解析了东北太平洋浅海海山——科布海山（Cobb Seamount）上的大型底栖外栖动物（mega-epifauna）群落的结构、多样性与分布格局。研究借助水下航行器，对34米至1154米水深范围内的底栖生物与海底环境开展目视调查，共获取约1600幅单幅面积约5平方米的图像。研究对隶属于11个门（phyla）的74个分类群（taxa）进行分析，最终划分出9个群落。每个群落均以具备生物构建功能或作为初级生产者（primary producer）的分类群为典型代表。多数界定群落的特征分类群均为冷水珊瑚（cold-water corals）、海绵（sponges）或藻类（algae）。群落整体呈现环绕海山的带状分布特征，且水深始终被证实为调控群落构建过程的最强环境替代指标（environmental proxy）。群落结构剩余的变异部分可由底质类型（substrate type）、地形粗糙度（rugosity）与坡度加以解释。本研究利用船载多波束测深（multibeam bathymetry）数据衍生的环境指标，对海山上的群落分布进行建模。该模型成功应用于科布海山220平方公里区域内的群落分布制图。本研究结果佐证了以下生态学范式：海山为生物多样性热点区域、多数海山群落面临底拖网捕捞（bottom fishing）扰动风险、海山是生物的庇护所（refugia），同时驳斥了“海山具有高特有性（endemism）”的观点。