Marine communities of the Bayu-Undan pipeline: comparisons with natural seabed communities to provide context for decommissioning

A major focus of the research was on fish, including the top 10 commercially important fishery species for this region, given their role as biodiversity indicators and the interest of this faunal group to a broad range of stakeholders. Field research was conducted in August-September 2019 aboard the AIMS vessel RV Solander. Five locations were surveyed along the pipeline route each location included the pipeline and surrounding natural seabed ecosystems out to a maximum distance of 6 km from the pipeline.A suite of methods was employed to characterise seabed morphology and associated biota. A multibeam echosounder acquired bathymetry raster data which revealed seabed depth and morphology. Subsequent derivative datasets produced environmental predictors of benthos describing seafloor structure and complexity. Towed video was used to collect high resolution imagery of benthic communities along 1.5km transects, randomly stratified across different habitat types, where visibility permitted. As it was not possible to perform towed video transects along the pipeline in high currents and low visibility, information on benthic communities colonising the pipeline was obtained through the analysis of existing remotely operated vehicle (ROV) imagery of the pipeline that was collected in 2017 by ConocoPhillips. Fish species richness and abundance, in addition to the size of commercially important fish species, were obtained using baited remote underwater stereo-video systems (stereo-BRUVs) with sampling along the pipeline and randomly stratified across natural seabed ecosystems at each location. The size of commercially important fish species was converted to biomass and beach value ($). AIMS historical data on benthic habitats and fish diversity were included to provide context and regional assessments of marine communities

本研究的核心聚焦对象为鱼类，涵盖该区域十大商业重要性渔业物种——鉴于鱼类兼具生物多样性指示物种的属性，且该类群动物可吸引广泛利益相关方的关注。野外调查于2019年8月至9月期间在澳大利亚海洋科学研究所（AIMS）的RV Solander号科考船上开展。沿管道路由共布设5个调查点位，每个点位涵盖管道及周边距管道最大6公里范围内的自然海底生态系统。本研究采用多类方法对海底地貌及相关生物群落进行表征：多波束测深声呐采集了水深栅格数据，以此反演海底深度与地貌形态；后续生成的衍生数据集可作为底栖生物的环境预测因子，用以描述海底结构与复杂度。在能见度符合要求的前提下，通过拖曳式视频系统沿1.5公里长的样带采集底栖生物群落的高分辨率影像，样带按不同生境类型进行随机分层布设。由于在强流及低能见度条件下无法开展沿管道的拖曳式视频样带调查，研究团队通过分析康菲石油（ConocoPhillips）2017年采集的管道区域现有遥控水下机器人（ROV）影像，获取了附着于管道的底栖生物群落相关信息。针对商业重要性鱼类的物种丰富度、丰度及个体体长，研究采用诱饵式远程水下立体视频系统（stereo-BRUVs）开展采样：采样沿管道路由布设，并在每个点位的自然海底生态系统中按生境类型进行随机分层。将商业重要性鱼类的个体体长转换为生物量及上岸产值（单位：美元）。研究纳入了AIMS关于海底生境与鱼类多样性的历史数据集，用以提供海洋群落的背景信息及区域评估依据。