Quantifying ecosystem resilience: catastrophic collapse and recovery of a large river food web

2013年7月初，参与肯尼特河沿岸河蝇种群生物监测的公民科学家首次发现了英国最大的农药污染事件之一的影响，当时据报道，肯尼特河沿岸15公里的地区有无脊椎动物灭绝。英国环境局接到了通知，目前为止，泄漏的源头被追溯到马尔伯勒的一个水处理厂，在那里，广泛使用的有机磷农药毒死蜱被意外排放到河里。污水处理厂的进一步排放立即停止：因此，我们正在处理影响整条河三分之一以上的单点源事件。这项紧急拨款的目的是在空间（从局部斑块到100米范围，超过6公里的河流长度）和时间（从泄漏后的几天到一年）以及生物组织（从基因到生态系统）的多个尺度上尽可能全面地采样河流的生物群。我们将收集的样本将使我们能够评估泄漏后的影响和初步恢复情况。我们还可以获得大量的公民科学家生物监测数据这些数据是方舟志愿者每月从撞击前后的几十个地点收集的。，这将补充我们新的密集抽样。我们的样本收集将从泄漏日期开始以大约对数间隔的时间间隔进行，因此我们可以将其提前加载到最初的急性和直接阶段，同时也能够在扰动波及食物网时跟踪慢性和间接影响。这个独特的案例研究将为我们提供宝贵的新见解，让我们了解自然系统的脆弱性和复原力，特别是农药的影响是如何远远超出其通常的目标生物（在这种情况下是无脊椎动物）。我们选择了6个研究区域（泄漏的3个上游和3个下游，间隔1公里），其深远影响已经明显超出了无脊椎动物灭绝的影响：例如，鱼类没有食物，微生物没有消费者来控制。因此，食物网已经在经历深刻的重组，我们预测，在进入恢复阶段之前，泄漏的直接后果将继续加剧——农药的停留时间很短，所以现在显现的影响是无脊椎动物灭绝的后果。由于紧急拨款仅限于1年的资金和6.5万英镑，我们专注于紧急样本收集和初步实验室处理，针对样本，日期和地点的子集进行最少的分析工作。我们将申请通过其他资助计划（例如NERC标准补助金）处理其余款项。我们的跨学科团队将收集前所未有的广度和深度的样本：从分子元系统学，定量食物网表征和生态系统功能的多种措施。这些数据将使我们能够在纯生态学和应用生态学中提出许多新颖的问题，并调查跨组织层面仍然很大程度上未知的联系。例如，微生物生物膜是否开启了特定的基因来处理农药，当无脊椎动物释放它们的控制时，它们的繁殖是否会威胁到当地的鱼类种群，使系统在夜间缺氧，因为呼吸作用剥夺了水中的氧气？在传统的实验室生态毒理学研究中无法检测到这种复杂的、间接的影响——它们只能在大范围的野外扰动中看到，但是对农药泄漏的反应进行如此全面和协调的覆盖以前从未尝试过。这项研究将提供独特的有价值的样本和最终的数据，以解决我们目前对淡水压力源影响的认识中的这一明显差距。

In early July 2013 the impacts of one of the UK's largest pesticide pollution events were first detected by citizen scientists involved in biomonitoring of riverfly populations along the River Kennet, as local extinctions of invertebrate life were reported along 15km of the river's length. The Environment Agency were notified and the source of the spill has so far been tracked back to a water treatment works in Marlborough, where it appears the widely-used organophosphate pesticide Chlorpyrifos was accidentally discharged into the river. Further discharges from the treatment works were immediately suspended: thus we are dealing with a single point source event that has affected over 1/3 of the entire river. This Urgency Grant is designed to sample the river's biota as comprehensively as possible over multiple scales in space (from local patches to 100m reaches, over 6km of the river's length) and time (from days to one year after the spill) and across multiple levels of biological organization (from genes-to-ecosystems). The samples we will collect will enable us to assess both the impact and initial recovery following the spill. We also have access to extensive citizen scientist biomonitoring data collect by ARK volunteers on a monthly basis from dozens of sites along the river both before and after the impact., which will complement our new intensive sampling. Our sample collection will be spaced through time at approximately logarithmic intervals from the date of the spill, so we can front-load it towards the initial acute and direct phase, while also being able to track chronic and indirect effects as the perturbation ripples through the food web. This unique case study will give us invaluable new insights into of the fragility and resilience of natural systems, and especially of how pesticide effects are felt far beyond those of their usual target organisms (invertebrates in this case). We have selected 6 study reaches (3 upstream and 3 downstream of the spill, separated by 1km intervals), and profound effects are already evident beyond those of invertebrate extinctions: for instance, fish are being left without food and microbes without consumers to keep them in check. The food web is therefore already undergoing profound restructuring, which we predict will continue to intensify in the immediate aftermath of the spill before entering the recovery phase - the pesticide has a very short residence time, so effects being manifested now are the consequences of its extirpation of the invertebrate fauna.As Urgency grants are limited to 1 year of funding and £65k we are focusing on urgent sample collection and preliminary laboratory processing, with minimal analytical work targeting a subset of samples, dates and sites. We will apply to process the remainder via other funding schemes (e.g. NERC Standard Grants). Our interdisciplinary team will collect an unprecedented breadth and depth of samples: from molecular metasystematics, to quantitative food web characterization and multiple measures of ecosystem functioning. The data will allow us to ask numerous novel questions in both pure and applied ecology, and to investigate the still largely unknown links across organizational levels. For instance, do the microbial biofilms switch on specific genes to process the pesticide and do their blooms when released from control by invertebrates threaten the local fish populations by pushing the system towards anoxia at night as respiration strips the oxygen from the water? Such complex, indirect effects cannot be detected in traditional laboratory ecotoxicological studies - they can only be seen in large field perturbations, but such a comprehensive and co-ordinated coverage of responses to a pesticide spill have never been attempted before. This study will deliver uniquely valuable samples - and ultimately data - to address this glaring gap in our current knowledge of stressor impacts in fresh waters.