BIOSEDIMENTOLOGICAL CASCADES: THE EFFECTS OF WADING BIRDS ON THE EROSION, PROPERTIES AND ECOSYSTEM SERVICES OF INTERTIDAL MUDDY SEDIMENTS

生物沉积学级联：涉禽对潮间带泥质沉积物的侵蚀、性质和生态系统服务的影响

• 批准号: 1652027
• 金额: --
• 依托单位: University of East Anglia
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2015
• 资助国家: 英国
• 起止时间: 2015 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-1652027
• 关键词: BIOSEDIMENTOLOGICAL; CASCADES; EFFECTS; WADING; BIRDS

Coastal habitats, including intertidal mudflats, are one of the planets most imperiled ecosystems, disappearing 4-10 ten times faster than tropical rainforest and declining in the UK 10 times faster than they are being created. Mudflats are at the forefront of climate driven changes such as sea level rise. They provide numerous ecosystem services, including coastal protection and primary productivity, supporting a diverse and important biota. Muddy intertidal sediments are intrinsically linked with their fauna and flora and are therefore biologically-mediated systems. The biota strongly influence sediment processes (e.g. erosion/accretion dynamics), and changes to sediments influence the biota that live in the sediment (e.g. productivity). Previous studies have highlighted the importance of biota to sediment dynamics and vice versa; in particular, the ability of benthic microalgae to stabilise sediments. Sediment stability responds to temporal and spatial variability in biota and sediment properties, often in an apparently idiosyncratic fashion. There is increasing recognition that this is caused by a complex interaction of direct and indirect processes. Advancing our knowledge of how biotic and abiotic processes interact to mediate sediment erosion is vital for predicting and mitigating the effects of climate change on these important habitats. One understudied, but potentially highly significant impact is how wading birds and their changing migration patterns will affect the ecosystem services of biostabilisation, nutrient flux and productivity by microphytobenthos. Previous research has shown that the presence of wading birds causes significant changes in benthic macrofauna behaviour, driving knock-on effects on microalgae, which causes significant changes to ecosystem services such as the erosion threshold and productivity. However, these remain poorly understood, thus the impacts of future changes in bird migration are difficult to predict. OBJECTIVESThis project will experimentally manipulate the density and species composition of wading birds in the field using size selective exclusion cages, to investigate how changing wading bird density and species composition alters biostabilisation, processes of erosion and deposition, sediment biogeochemical properties, nutrient flux and benthic microalgae productivity (either directly or indirectly). Experiments will be done on muddy intertidal sites along the Norfolk and Essex coastline.This will improve our understanding of the biological/physical interactions that drive these properties and processes. Teasing apart such interactions is essential to advancing our knowledge of how biotic and abiotic components mediate sedimentary processes and alter delivery of vital ecosystem services in coastal habitats. The project will use advanced techniques, such as PAM fluorometry, erosion devices (FloWave, Cohesive Strength Meter) and cryogenic coring techniques. Sediment cores will be used to measure a suite of sediment properties, including: the water content, grain size, bulk density, organic matter, carbohydrates, exopolymeric substances creating sediment cohesion, pigments and nutrients. This will be the first time such a suite of techniques has been combined to investigate the effects of wading birds on intertidal sediments. This will provide essential data for improving models of near-shore sediment dynamics, informing decision making around coastal adaptive management strategies and mitigating climate change.

包括潮间泥滩在内的沿海栖息地是地球上最危险的生态系统之一，其消失速度比热带雨林快4-10倍，在英国，其消失速度比其创建速度快10倍。泥滩是气候变化的前沿，如海平面上升。它们提供许多生态系统服务，包括海岸保护和初级生产力，支持多样化和重要的生物群。泥质潮间带沉积物与其动物群和植物群有着内在的联系，因此是生物介导的系统。生物群对沉积过程（如侵蚀/增生动态）有很大影响，而沉积物的变化则影响生活在沉积物中的生物群（如生产力）。以往的研究强调了生物区系对沉积物动力学的重要性，反之亦然;特别是底栖微藻稳定沉积物的能力。沉积物的稳定性对生物区系和沉积物性质的时间和空间变异性作出反应，往往是以一种明显的特殊方式。人们日益认识到，这是由直接和间接过程的复杂相互作用造成的。提高我们对生物和非生物过程如何相互作用以介导沉积物侵蚀的认识，对于预测和减轻气候变化对这些重要生境的影响至关重要。一个未充分研究，但潜在的非常重要的影响是如何涉水鸟类及其不断变化的迁移模式将影响生态系统服务的生物稳定，营养通量和生产力的微型植物底栖生物。先前的研究表明，涉禽的存在导致大型底栖动物行为发生重大变化，对微藻产生连锁反应，从而导致侵蚀阈值和生产力等生态系统服务发生重大变化。然而，这些仍然知之甚少，因此很难预测未来鸟类迁徙变化的影响。本项目将使用大小选择性排除笼在野外实验性地操纵涉禽的密度和物种组成，以研究涉禽密度和物种组成的变化如何改变生物稳定性、侵蚀和沉积过程、沉积物生物地球化学性质、营养通量和底栖微藻生产力（直接或间接）。实验将在诺福克和埃塞克斯海岸线沿着泥泞的潮间带进行，这将提高我们对驱动这些特性和过程的生物/物理相互作用的理解。梳理这种相互作用是必不可少的，以推进我们的知识，生物和非生物成分如何介导沉积过程和改变提供重要的生态系统服务的沿海栖息地。该项目将使用先进技术，如PAM荧光测定法、侵蚀装置（FloWave、内聚强度计）和低温取芯技术。沉积物岩心将用于测量一系列沉积物特性，包括：含水量、粒度、体积密度、有机物、碳水化合物、形成沉积物凝聚力的外聚合物、色素和营养物质。这将是第一次将这样一套技术结合起来，调查涉水鸟类对潮间带沉积物的影响。这将为改进近岸沉积物动力学模型提供基本数据，为沿海适应性管理战略和减缓气候变化的决策提供信息。