Long-term changes in coastal ecosystem structure and functions: understanding the effects of harvesting, habitat alteration, and climate change

沿海生态系统是海洋的重要结构和功能组成部分，为人类福祉提供基本服务，包括海产食品生产、营养循环、娱乐和沿海保护。然而，它们在历史时间尺度上发生了深刻的变化，并继续被多种人类活动所改变。为了评估和妥善管理现在和将来的海洋资源和沿海生态系统，必须了解过去长期变化的范围、规模和后果。就像了解病人的病史可以大大提高诊断和治疗的成功率一样，重建历史变化为当前的研究和管理提供了关键的背景。我的研究计划是独一无二的，在提供这种历史背景下，同时分析正在发生的变化及其在生态系统规模的后果。我们在评估海洋种群，特别是哺乳动物和鱼类等脊椎动物种群的历史变化方面取得了重大进展。我们综合了过去几个世纪人口下降的程度和最近由于保护增加而恢复的程度，并量化了主要的生态系统后果，如生物多样性，食物网复杂性和稳定性的变化。然而，虽然脊椎动物得到了更多的保护和管理，但在加拿大和世界各地，对海洋无脊椎动物和植物的开发正在迅速扩大，几乎没有进行种群评估，生态系统后果基本上未知。与大多数鱼类不同，无脊椎动物和植物通常在捕食者-猎物关系之外发挥重要的生态系统作用，包括提供栖息地、水过滤和营养循环。这些低营养级物种也对日益增加的气候变化和营养负荷十分敏感。因此，在接下来的五年里，我的研究将重建海洋无脊椎动物和植物的长期变化，并分析其对沿海生态系统结构，功能和它们为人类提供的服务的后果。具体而言，我们将评估历史研究调查和渔业统计数据，以得出海洋植物和无脊椎动物丰度和分布的长期变化。为了了解所观察到的变化的后果，我们将采用实验和实地数据的荟萃分析来量化这些物种提供的生态系统功能和服务，包括栖息地提供，水过滤，碎屑清除，碳储存和营养循环。作为第三个要素，我们将根据实地调查数据建立食物网模型，并使用来自世界各地的沿海生态系统模型来分析海洋植物和无脊椎动物捕捞对其他具有商业和保护价值的物种以及整体生态系统结构和功能的影响。最后，我们将使用实验室实验来测试气候变暖和营养负荷对生境营造植物及其相关群落的影响。实验结果和全球气候模型将被用作我们的生态系统模型的投入，以评估预测的气候变化对海洋生态系统的更广泛影响。总的来说，拟议的工作将填补关键的知识空白，这对于了解沿海海洋过去和正在发生的变化，预测其对海洋生态系统和人类社会的更广泛影响，并为基于生态系统的海洋管理和保护方法提供信息。因此，这项研究将支持管理者和决策者，并有利于资源使用者和整个社会。它将推进我们对海洋生态学，环境历史和生态预测的基本理解，并培养学生在创新，跨学科的研究领域。

Coastal ecosystems are important structural and functional components of the ocean and provide essential services to human well-being, including seafood production, nutrient cycling, recreation and coastal protection. Yet they have been deeply transformed over historical time scales and continue to be altered by multiple human activities. In order to assess and properly manage marine resources and coastal ecosystems today and for the future, it is essential to understand the range, magnitude and consequences of long-term changes in the past. Like knowledge of a patient's medical history greatly improves the success of diagnosis and treatment, reconstruction of historical changes provides critical context for current study and management. My research program is unique in providing this historical context while analyzing ongoing changes and their consequences at the ecosystem scale. We have made significant progress in assessing historical changes in marine populations, particularly for vertebrates such as mammals and fish. We synthesized both the extent of population declines over past centuries and recent recoveries due to increased conservation, and quantified major ecosystem consequences, such as changes in biodiversity, food-web complexity and stability. Yet while vertebrates have received increased protection and management, exploitation of marine invertebrates and plants is rapidly expanding, both in Canada and around the world, with little population assessment and largely unknown ecosystem consequences. In contrast to most fish, invertebrates and plants often play important ecosystem roles beyond predator-prey relationships, including habitat provision, water filtration and nutrient cycling. These low-trophic level species are also sensitive to increasing climate variability and nutrient loading. Over the next five years my research will therefore reconstruct long-term changes in marine invertebrates and plants, and analyze their consequences for coastal ecosystem structure, functions, and the services they provide for humans. Specifically, we will assess historical research surveys and fisheries statistics to derive long-term changes in the abundance and distribution of marine plants and invertebrates. To understand the consequences of observed changes, we will employ meta-analysis of experimental and field data to quantify the ecosystem functions and services provided by these species, including habitat provision, water filtration, detritus removal, carbon storage and nutrient cycling. As a third element, we will build food-web models from field-survey data and use coastal ecosystem models from around the world to analyze the consequences of marine plant and invertebrate harvesting on other species of commercial and conservation interest, and overall ecosystem structure and functions. Finally, we will use laboratory experiments to test the effects of climate warming and nutrient loading on habitat-building plants and their associated communities. Experimental results and global climate models will then be used as inputs in our ecosystem models to assess the broader consequences of projected climate change on marine ecosystems. Taken together, the proposed work will fill critical knowledge gaps that are important to understand past and ongoing changes in the coastal ocean, predict their broader consequences for marine ecosystems and human society, and inform an ecosystem-based approach to marine management and conservation. As such, this research will support managers and decision makers, and benefit resource users and society as a whole. It will advance our fundamental understanding in marine ecology, environmental history and ecological forecasting, and train students in an innovative, inter-disciplinary research field.