A survey of the region eastward of Nantucket provided an opportunity to examine the cold temperate–boreal boundary along the high‐energy Great South Channel. Here described are the benthic macroinvertebrate community types encountered, with a focus on the influence of climate change on the range boundaries of the benthic biomass dominants and the potential existence of transient multiple stable states. The survey identified three primary community types. The shallowest sites were occupied by a surfclam‐dominated community, comprising an abundance of large (≥150 mm) surfclams, and a few common attached epibiota primarily attached to exposed surfclam shell. Two communities exist at intermediate depths, one dominated by submarket and small market‐size surfclams (<150 mm) and the other, created by mussel mats and their attendant epibiota, crabs, sea urchins, and other mobile epifauna. Mussels are a foundational species, establishing a hard‐bottom terrain conducive to these other denizens in soft‐bottom habitat. Cobbles were nearly ubiquitous, rocks were routinely recovered, and boulders were encountered occasionally. Slow growing attached epibionts were exceedingly rare and mobile epifauna were not obviously associated with these large sedimentary particles; nor were the surfclam or mussel communities. The frequency of barnacle scars suggests sediment scour under the high‐flow regime characteristic of the surveyed region, which voids the habitat potential of these sedimentary particles. The abundance of surfclam shell indicates that surfclams have inhabited the shoaler depths for an extended time; limited shell at deeper sites supports the inference from the absence of large animals that these sites are relatively newly colonized and represent further evidence of an offshore shift in range brought on by increasing bottom water temperatures. The dichotomous nature of the two primary community types at mid‐depths suggests that these two communities represent multiple stable states brought on by the interaction of an invading cold temperate species with the receding boreal fauna resulting in a transient intermingling of species, which, however, structure the habitat into exclusionary stable states rather than overlapping in a co‐occurrence ecotone.

中文翻译：

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底栖动物无脊椎动物群落在变化范围内的混杂：“南塔基特东部”大西洋海浪调查和瞬态多重稳态的存在

对楠塔基特（Nantucket）东侧地区的调查提供了一个机会，可以检查高能量的大南海峡沿线的冷温带-北方边界。这里描述的是底栖大型无脊椎动物群落类型，重点是气候变化对底栖生物量优势区域范围边界的影响以及瞬态多个稳定状态的潜在存在。调查确定了三种主要的社区类型。最浅的位置被一个以冲浪蛤为主的群落所占据，包括大量的大型（≥150 mm）冲浪蛤，以及一些主要附着在裸露的冲浪蛤壳上的常见附生生物。在中层深度存在着两个群落，一个群落以子市场和小型市场规模的surfclams（<150 mm）为主，另一个群落由贻贝垫及其伴随的附生生物，蟹，海胆和其他流动动物。贻贝是基础物种，在软底栖息地中建立了有利于这些其他居民的硬底地形。鹅卵石几乎无处不在，岩石经常被回收，偶尔会遇到巨石。缓慢生长的附着表皮动物极少见，流动的表皮动物与这些大的沉积颗粒没有明显的联系。冲浪蛤或贻贝社区也没有。藤壶疤痕的频率表明，在被调查区域的高流量状态特征下，沉积物会冲刷，这使这些沉积物的生境潜力丧失了。大量的表层蛤壳表明，表皮已经在浅滩深处居住了很长时间。在较深的地方，有限的壳支持没有大型动物的推断，这些地方是相对较新的殖民地，并代表着由底水温度升高引起的离岸范围变化的进一步证据。中等深度的两个主要群落类型的二分性表明，这两个群落代表了多个稳定状态，这是由于入侵的冷温带物种与后退的北方动物区系的相互作用而产生的，从而导致物种的短暂混合。将栖息地构造成排他性稳定状态，而不是在共生过渡带中重叠。