Ecosystem engineers and coastal sedimentary communities

沉积海底覆盖了海洋领域的绝大多数区域。然而，我们对形成它们的生物多样性和功能的过程的了解仍然不完整。过去，大多数理论预测，在局部尺度上，捕食和物理因素将在调节沉积群落方面发挥最重要的作用。然而，许多随后的研究也表明，栖息地形成物种的建立对于形成这些系统的多样性和功能同样至关重要。这些基础物种更一般地被称为(自生)生态系统工程师，他们有能力创造或改变栖息地的属性，促进新的、更复杂的群落的发展。生态系统工程师的角色已经在岩石海岸、海藻森林、红树林、珊瑚礁，甚至盐沼系统中得到了很好的研究。然而，在非结构化沉积海底，特别是在大西洋加拿大的海底，仍有许多有待探索和测试。越来越多的证据表明，生态系统工程师可能在沉积环境中的群落属性和服务方面发挥关键作用，但关于他们在不同营养水平内和不同营养水平之间驱动物种相互作用的作用，缺乏足够的信息。这在我们目睹有能力开采、消耗或扰乱当地生态系统工程师的非土著物种的持续传播之际是相关的，并引发了关于他们的相互作用以及最终这些工程师在沉积系统中的实际作用的相关问题。这项研究计划集中在大西洋加拿大沉积海岸线上的几位著名的生态工程师身上：蓝色贻贝、东部牡蛎、鳗草和岩藻。该计划的主要目标是测试这些生态工程师对周围沉积动物群的组装和物种相互作用的影响，以及非土著物种对它们的潜在改变。通过对三个主要研究情景的研究，提出了六个假设：生态系统工程师作为基础结构和功能的推动者，他们作为自上而下相互作用的调解人，以及他们作为本地-入侵物种相互作用的调解人的角色。在大西洋地区，特别是爱德华王子岛沿海的沉积区已经进行了大量的勘探工作，为提出和检验这些假设提供了基础。这项研究计划的结果将有助于我们了解生态系统工程师及其推动生物相互作用的角色。这样的结果也将对社区管理、营养复杂性和海岸保护的理论产生影响。

Sedimentary bottoms encompass a vast majority of the marine realm. Yet, our understanding of the processes that shape their biodiversity and function remains fragmentary. In the past, most theory predicted that at the local scale predation and physical factors would play a paramount role regulating sedimentary communities. However, numerous subsequent studies have also showed that the establishment of habitat-forming species is as critical to shape diversity and function in these systems. These foundation species, more generically known as (autogenic) ecosystem engineers, have the ability to create or alter the properties of a habitat, promoting the development of new, more complex communities. The role of ecosystem engineers has been well studied in rocky shores, kelp forests, mangroves, coral reefs, and even saltmarsh systems. However, in unstructured sedimentary bottoms, in particular those in Atlantic Canada, much remain to be explored and tested. Mounting evidence suggests that ecosystem engineers may play key roles on community attributes and services in sedimentary settings, but not enough information is available on their role driving the species interactions occurring within and among different trophic levels. This is relevant at a time when we witness the ongoing spread of non-indigenous species that have the ability to exploit, consume or disrupt local ecosystem engineers, and opens relevant questions about their interactions and, ultimately, about the actual role of these engineers on sedimentary systems. This research program focuses on several prominent ecosystem engineers present and scattered along sedimentary shorelines of Atlantic Canada: blue mussels, eastern oysters, eelgrass, and rockweeds. The main goal of this program is testing the effects of these ecosystem engineers on the assembly and species interactions of surrounding sedimentary infauna and their potential alteration by non-indigenous species. Six hypotheses are addressed by working on three main research scenarios: Ecosystem engineers as drivers of infaunal structure and function, their role as mediators of top-down interactions, and their role as mediators of native-invader species interactions. A considerable amount of exploratory work already conducted in sedimentary areas in the Atlantic region, and coastal Prince Edward Island in particular, provides the basis to propose and test each of these hypotheses. The outcome of this research program will contribute to our knowledge on ecosystem engineers and their role driving biological interactions. Such outcome will also have implications for theory on community regulation, trophic complexity, and coastal conservation.