Point sampling of soft sediment macrofauna was conducted across the shelf and upper slope in the northeastern Pacific Ocean off the United States Pacific Northwest coast to conduct a regional analysis of species composition and use species assemblages to define habitat types. Analyses focused on linking spatial variability in macrofauna assemblages with measured environmental parameters using nMDS plots and the LINKTREE routine in Primer. Depth was the primary structuring variable (i.e., macrofauna species assemblages first separated by depth) with sediment parameters (percent fines, grain size, and total organic carbon) secondary and nearly as statistically important. A depth break of ~90 m was the environmental variable that correlated with the greatest separation among our stations based on differences in macrofaunal assemblages, which is not a classically described depth break for shelf macrofauna. The next largest changes in assemblage composition were at 43 m and 200 m. Within each of these depth zones on the shelf, we detected significant differences in assemblages related to different sediment grain sizes. Below the 200 m break – a depth traditionally delineating the continental shelf and slope – subsequent changes in assemblage composition were detected at 221 m and 445 m depth breaks; further delineations in assemblages related to sediment parameters were not detected. Knowing how macrofaunal communities vary with grain size and depth can inform future site surveys, develop tools for mapping macrofauna habitat suitability based primarily on these physical factors, and develop hypotheses of how benthic communities might be affected by offshore projects.

在美国太平洋西北海岸以外的东北太平洋的陆架和上坡进行了软沉积物大型动物的点采样，以进行物种组成的区域分析并使用物种组合来定义栖息地类型。分析的重点是使用nMDS图和Primer中的LINKTREE例程将大型动物群落中的空间变异性与测得的环境参数联系起来。深度是主要的结构变量（即，首先被深度分开的大型动物群组合），其次是沉积物参数（细粉百分比，粒度和总有机碳），在统计上也几乎一样重要。约90 m的深度断裂是环境变量，它与基于大型动物群差异的站点之间的最大间隔有关，这不是架子上大型动物的经典描述的深度突破。组合成分的第二大变化是在43 m和200 m处。在架子上的每个深度区域内，我们检测到与不同沉积物粒度有关的组合的显着差异。在200 m断裂以下（传统上划定了大陆架和斜坡的深度）以下，在221 m和445 m深度断裂处检测到组合成分的后续变化；没有发现与泥沙参数有关的组合的进一步描述。了解大型动物群落如何随粒度和深度而变化可以为将来的现场调查提供依据，开发主要基于这些物理因素来绘制大型动物栖息地适应性的工具，并提出关于底栖生物群落如何受到海上项目影响的假设。