Hydroscape:connectivity x stressor interactions in freshwater habitats

所有类型的生态系统在某种程度上都表现出连通性。然而，连通性是水生系统的典型特征。连通性在淡水中很重要，因为它是能源、材料、生物和遗传资源在景观水文单元（“水景”）内部和之间流动的手段。水文连通性是应对多种气候、生物、化学和物理压力的特别有效载体，尽管其他形式的连通性也能将淡水生态系统联系起来。我们的建议解决了连通性和压力源如何相互作用以决定淡水生物多样性和生态系统功能的基本问题。互联互通是多方面的。它可能是有形的——水下坡或冲积平原，或更微妙的——陆地有机物被纳入水生食物网。动物和人自然倾向于淡水，因此提供了额外的传播媒介，可以将繁殖体带到孤立的地点。连接可以是被动的，也可以是主动的，并且发生在从本地到全球的各个层面。淡水科学家认识到连通性在诸如河流连续体和洪水脉冲概念等关键范例中的基本作用。陆水连通性也是集水区管理的基本原则。然而，在现实中，长期以来关注单个压力源、地点、分类群体或栖息地的传统，导致了对地球上最内在联系的资源的高度脱节的看法。虽然普遍承认需要对水管理采取综合办法，但对淡水基础设施的这一最基本部分缺乏了解。这是应付重大社会挑战的一个严重障碍，即在面对不断增加的人为压力时维持环境的可持续性。如果对淡水景观没有一个更综合的看法，我们很难回答基本问题。其中包括(i)生物、营养物质和能量如何在景观内部和景观之间自然流动？（ii）不同的压力源（单独或组合）如何改变这个基本模板？（iii）在很大程度上推动连通性的土地覆盖和淡水基础设施的广泛改变，如何重新分配压力并改变其影响？（iv）在寻求恢复生物多样性和生态系统功能时，应如何优先考虑目前已广泛实施的减少压力源和改变连通性的措施？我们的主要目标是：(1)确定水文、空间和生物连通性如何影响对比景观类型下的淡水生态系统结构和功能；(2)利用这种理解来预测全国淡水将如何应对(i)多种相互作用的压力和（ii）旨在减少压力和/或改变连通性的管理行动。我们将在不同的空间尺度（景观vs国家）和时间尺度（次年尺度到年代际尺度vs百年尺度）上开展工作，并结合使用互补的、完善的和更新颖的分子和稳定同位素技术来实现这些目标。我们将把现有的数据来源（例如存档的沉积物岩心、生物调查和国家数据库中保存的数百万条记录）与有针对性的采样结合起来，以最大限度地提高成本效益，并实现跨栖息地和生态系统的广泛覆盖。景观规模的思考已经成为自然保护和环境机构的新咒语，但目前缺乏确保对气候变化的适应能力以及支持大规模水生景观保护和恢复所需的知识。在这方面，了解生物多样性和生态系统功能如何响应淡水中不断变化的连通性和压力源是至关重要的。拟议研究的成果将提供目前迫切需要的对水景的综合理解。

All types of ecosystems exhibit connectivity at some level. However, connectivity is the quintessential property of aquatic systems. Connectivity matters in freshwaters because it is the means by which energy, materials, organisms and genetic resources move within and between hydrological units of the landscape (the 'hydroscape'). Hydrological connectivity is a particularly effective vector for multiple climatic, biological, chemical and physical stressors, although other forms of connectivity also link freshwater ecosystems. Our proposal addresses the fundamental question of how connectivity and stressors interact to determine biodiversity and ecosystem function in freshwaters.Connectivity is multifaceted. It may be tangible - water moves downhill or over floodplains, or more subtle - terrestrial organic matter is incorporated into aquatic food webs. Animals and people naturally gravitate to freshwaters, thus providing additional dispersal vectors that can carry propagules to isolated sites. Connectivity may be passive or active and occurs across scales from the local to the global. Freshwater scientists recognise the fundamental role of connectivity in key paradigms such as the river continuum and flood pulse concepts. Land-water connectivity is also the founding principle behind catchment management. However, in reality, a long tradition of focusing on individual stressors, sites, taxonomic groups or habitats, has led to a highly disjointed view of the most intrinsically interconnected resource on the planet. While the need for an integrated approach to water management is universally acknowledged, an understanding of this most fundamental part of the infrastructure of freshwaters is lacking. This is a serious obstacle to meeting critical societal challenges, namely the maintenance of environmental sustainability in the face of multiplying human-induced stresses. Without a more integrated view of the freshwater landscape we struggle to answer basic questions. These include (i) how do organisms, nutrients and energy move naturally within and between landscapes? (ii) how is this basic template altered by different stressors, singly or in combination? (iii) how has widespread alteration of land cover and of the basic infrastructure of freshwaters that largely drives connectivity, redistributed pressures and modified their effects? (iv) how should reductions in stressors and changes to connectivity, that are now widely implemented, be prioritised when seeking to restore biodiversity and ecosystem function?Our primary aims are to (1) determine how hydrological, spatial and biological connectivity impact on freshwater ecosystem structure and function in contrasting landscape types, and (2) use this understanding to forecast how freshwaters nationally will respond to (i) multiple, interacting pressures and (ii) management actions designed to reduce pressures and/or alter connectivity. We will achieve these aims by working at different spatial (landscape vs national) and temporal (sub-annual to decadal vs centennial) scales and using a combination of complementary well established and more novel molecular and stable isotope techniques. We will combine existing data sources (e.g. archived sediment cores, biological surveys and the millions of records held in national databases) with targeted sampling to maximise cost effectiveness and achieve a cross habitat and ecosystem wide reach. Landscape scale thinking has become the new mantra of nature conservation and environmental bodies but the knowledge needed to ensure resilience to climate change and to underpin large scale conservation and restoration of aquatic landscapes is currently lacking. In this regard an understanding of how biodiversity and ecosystem function respond to the changing connectivity x stressors arena in freshwaters is critical. The outputs of the proposed research will deliver the integrated understanding of the hydroscape that is now required urgently.