Marine Ecosystem Assessment in a Patchy World: Are AUVs the Solution to Quantify Zooplankton?

CEFA是英国的一个机构，负责在海洋问题上向政府提供科学建议，为如何最好地管理英国水域的海洋生态系统提供决策信息。支持这一建议的数据传统上是由定点海洋观测站和几个船基监测调查网络收集的，它们分别提供时间和空间分辨率的数据。这些平台提供了定量评估海洋环境所需的数据，包括鱼类、浮游动物和物理驱动因素。然而，运输时间尤其昂贵。使用自主水下航行器(AUV)，特别是海洋滑翔机的新方法现在正在设计中。为了解释在这些新平台上收集的数据，并便于与现有方法进行比较，CEFA需要新的抽样策略。该项目旨在探索这些新技术，以利于未来的CEFAS科学调查，同时也解决与全球相关的令人兴奋的科学问题，即为什么浮游动物的分布是零散的。浮游动物是海洋生态系统的重要组成部分之一。它们在海洋食物网中发挥着重要作用，将能量从初级生产者转移到更大的生物体，例如具有重要商业价值的白鱼。在南大洋，它们本身就形成了一种可开发的资源(磷虾)。因此，浮游动物是生态系统健康的重要指标，但它们的抽样通常很差。与含有叶绿素的浮游生物不同，它们不能通过卫星图像进行量化。基于船舶的采样通常涉及部署网，这些网难以捕捉浮游动物分布的斑块。越来越多的努力致力于使用声学技术从船载回声探测仪估计浮游动物的数量，回声探测仪已经是监测小鱼的传统工具。该项目将评估和优化使用滑翔机搭载的回声探测仪进行生态系统评估，并应用这项技术来研究海洋环境中浮游动物的斑块及其原因。AUV技术正在彻底改变我们收集环境数据的方式，但我们需要知道如何将这些观察转化为对生态系统的统计稳健评估。许多海洋特征是零散的。例如，温度或电流速度可以在几百米的尺度上变化。生物分布甚至更加复杂，不仅受物理过程的驱动，还受食物可获得性或形成学校或蜂群的倾向等因素的影响。这个项目将使用高分辨率、一致的浮游动物分布测量及其物理和生物地球化学驱动因素，确定为什么它是斑块的，这种斑块是如何变化的，以及它是否可预测。在物理海洋科学中观测、理解和模拟亚中尺度的令人振奋的最新发展的基础上，该博士项目抓住同样的机会在亚中尺度推进生物海洋科学。该项目有四个相互关联的目标：(I)通过利用现有的声学数据集和海洋模型输出，优化AUV对浮游动物和鱼类分布和生物量的评估；(Ii)利用这些新开发的战略，结合船基调查进行滑翔机部署；(Iii)从物理背景解释观测到的浮游动物和鱼类分布，生物地球化学和水深控制以及捕食者-猎物动力学(IV)综合了对未来海洋监测系统设计的影响。博士生将由CEFA、BAS和UEA该领域的研究带头人指导，将专业知识汇集到声学、海洋滑翔机、海洋生物学、物理海洋学和海洋观测系统。他/她将接受多学科海洋海洋学、浮游动物生态学、渔业声学和海洋滑翔机使用方面的培训，受益于嵌入NERC EnvEast DTP。

Cefas are the UK agency tasked with providing scientific advice to government on marine issues, informing decisions on how best to manage the marine ecosystems in UK waters. The data underpinning this advice have traditionally been collected by a network of fixed-point ocean observatories and several ship-based monitoring surveys, that provide temporally- and spatially resolved data respectively. These platforms provide the data needed to quantitatively assess the marine environment including on fish, zooplankton and physical drivers. However ship time in particular is costly. New methods using autonomous underwater vehicles (AUVs), especially ocean gliders, are now being devised. To interpret the data collected on these new platforms and facilitate comparison with existing methods, Cefas require new sampling strategies. This project is designed to explore these new techniques to benefit future Cefas scientific surveys, whilst also addressing exciting scientific questions of global relevance on why zooplankton distributions are patchy. Zooplankton are one of the key components of the marine ecosystem. They play an important role in marine foodwebs, transferring energy from the primary producers to larger organisms, for example commercially important whitefish. In the Southern Ocean they form an exploitable resource (krill) in their own right. As such, zooplankton are important indicators of ecosystem health, yet they are generally poorly sampled. Unlike plankton that contain chlorophyll, they cannot be quantified from satellite imagery. Ship-based sampling often involves deployment of nets which struggle to capture the patchiness in zooplankton distribution. Increasingly, effort is devoted to the use of acoustics for estimating zooplankton abundance from ship-borne echo sounders, already a traditional tool to monitor small fish. This project will assess and optimise the use of glider-borne echo sounders for ecosystem assessment, and apply this technology to study the patchiness of zooplankton in the marine environment and its causes. AUV technologies are revolutionising the way we collect environmental data, but we need to know how to convert these observations into statistically robust assessments of the ecosystem.Many ocean characteristics are patchy. For example, temperature or current speed can vary over scales of a few hundred metres. Biological distributions are even more complex, driven not only by physical processes, but also by factors such as food availability or a tendency to form a school or swarm. This project will use high-resolution, coincident measurements of the patchy zooplankton distribution together with its physical and biogeochemical drivers, determine why it is patchy, how that patchiness varies, and whether it is predictable. Building on exciting recent developments in observing, understanding and modelling the submesoscale in physical marine science, this PhD project seizes the same opportunity to advance biological marine science at the submesoscale.The project has four interlinked objectives: (i)optimise AUV assessment of zooplankton and fish distribution and biomass by exploiting existing acoustic data sets and ocean model output(ii)conduct a glider deployment in conjunction with a ship-based survey using these newly-developed strategies(iii)interpret the observed zooplankton and fish distribution in the context of physical, biogeochemical and bathymetric controls and predator-prey dynamics(iv)synthesise the implications for design of future ocean monitoring systems.The PhD student will be supervised by research leaders in the field at Cefas, BAS and UEA, bringing together expertise infisheries acoustics, ocean gliders, marine biology, physical oceanography, and ocean observing systems. He/she will be trained in multidisciplinary seagoing oceanography, zooplankton ecology, fisheries acoustics and the use of ocean gliders, benefiting from embedding in the NERC EnvEast DTP.