Quantifying the hidden biodiversity, conservation value and effectiveness of fine sediment detention ponds in agri-environment schemes

根据欧盟水框架指令，过多的细沉积物（通常颗粒<2 mm）是水体未能达到良好生态状态的主要原因之一，其对整个营养食物网具有广泛公认的生态影响（Mathers等人，2017年）。虽然细颗粒泥沙的输入、输运和储存是河流功能的自然组成部分，但人为改变导致当代输入远远超过历史水平（柯林斯和张，2016）。为了解决这个问题，英国已经实施了一些措施来减少对水体的细沉积物输入，包括英国集水区敏感农业交付倡议（投资2900万英镑）和北方爱尔兰的“Interreg项目源开发”（490万英镑）。最近，2020年的农业法案将奖励英格兰的农民和土地管理者提供“公共产品”，例如根据环境土地管理计划（ELM：Gov.UK，2020）提高生物多样性，改善水质或减少洪水。处理河流细颗粒沉积物同时提高生物多样性的一种方法是安装沉积物捕集器和缓冲池（例如，见基于集水区的方法，2021年）。尽管它们在农业环境计划中广泛存在，但对沉积物减缓方法对景观生物多样性的贡献或其减少细颗粒沉积物污染对河流健康的有效性知之甚少。一些研究表明，包括人工和独特的静水水体在内的小型水体（Biggs等人，2017）可能支持大量的水生生物，除了那些具有高保护价值（Cerini等人，2020年）。该项目将与从事农业管理和监测的主要利益攸关方和项目伙伴合作，提供直接用于政策和现实世界环境管理的基本信息。该项目将力求：i）量化目前各种水生沉积物减缓方法的吸收和分布; ii）量化沉积物保留池的生物多样性和保护价值; iii）评估沉积物保留方法在减轻河流系统细沉积物压力方面的有效性。

Excessive fine sediment (typically particles <2mm) is one of the principal reasons for the failure of waterbodies to achieve good ecological status under the EU Water Framework Directive with widely acknowledged ecological effects for the entire trophic food web (Mathers et al., 2017). Although the input, transport, and storage of fine sediment is a natural component of river function, anthropogenic modifications have resulted in contemporary inputs far exceeding historic levels (Collins and Zhang, 2016). To combat this, a number of UK initiatives have been implemented to reduce fine sediment inputs to waterbodies including the English Catchment Sensitive Farming Delivery Initiative (£29M invested) and the 'Interreg project source to tap' in Northern Ireland (£4.9M). More recently, the Agricultural bill in 2020, will reward farmers and land managers in England for 'public goods' such as enhancing biodiversity, improving water quality or reducing flooding under the Environmental Land Management Scheme (ELM: Gov.UK, 2020). One means of tackling riverine fine sediment whilst also enhancing biodiversity is the installation of sediment traps and buffer ponds (e.g. see Catchment Based Approach, 2021).Despite their wide occurrence in agri-environment schemes, little is known about the contribution of sediment mitigation methods to landscape biodiversity or their efficacy for reducing fine sediment pollution for riverine health. Some research has suggested that small water bodies including artificial and unique lentic waterbodies (Biggs et al., 2017) may support high numbers of aquatic organisms in addition to those with high conservation value (Cerini et al., 2020). This project will work with leading stakeholders and project partners engaged in agricultural management and monitoring to provide essential information that will feed directly into policy and real-world environmental management. The project will seek to: i) quantify the current uptake and distribution of the various aquatic-based sediment mitigation methods; ii) quantify the biodiversity and conservation value of sediment retention ponds; and iii) assess the effectiveness of sediment retention methods in mitigating fine sediment pressures for riverine systems.