Table_1_Some Old Movies Become Classics – A Case Study Determining the Scientific Value of ROV Inspection Footage on a Platform on Australia’s North West Shelf.DOCX

The global oil and gas industry holds a vast archive of Remotely Operated Vehicle (ROV) inspection footage potentially containing useful long-term data on marine biological communities. With the upcoming era of decommissioning of oil and gas structures, it is timely to assess the usefulness of this footage for researching these communities. We used ROV inspection footage to characterize the sessile invertebrates and fishes associated with the Goodwyn Alpha Production Platform (GWA) on the North West Shelf of Australia between depths of 10 and 125 m during 2006 and 2008. Depth was a major driver of invertebrate assemblages, most likely due to specific requirements such as light, and differences between years were most likely from the physical detachment of species by cyclones and internal waves. Phototrophic species were mostly limited to the upper 50 m of the platform, including the hard coral Pocillopora sp. and the soft corals Nephthea sp. and Scleronephthya sp. In contrast, heterotrophic species including sponges, anemones, bryozoans, hydroids, bivalves such as Lopha folium and the hard coral Tubastrea spp., were distributed across all depths. We observed 1791 fish from at least 10 families and 19 species, including commercial species such as crimson seaperch (Lutjanus erythropterus), red emperor (L. sebae), saddle-tailed seaperch (L. malabaricus), mangrove jack (L. argentimaculatus) and trevally (Caranx spp.). Fish density increased significantly with depth during 2008, from a mean of 23 fish/50 m2 between 10 and 25 m to 3373 fish/50 m2 at 125 m, where small unidentified baitfish were abundant. The highest densities of commercial species occurred between 25 and 75 m depth, suggesting that mid-depth platform sections had high habitat value, a consideration when selecting decommissioning options. The greatest difficulties using the video were the poor lighting and resolution that inhibited our ability to identify sessile species with high taxonomic precision. However, the footage was useful for evaluating high-level biodiversity of the platform, understanding how fish and invertebrate communities changed with depth and comprehending the dynamic nature of the invertebrate community over time. Understanding the habitat value of structures will be necessary for making environmentally sound decommissioning decisions in the future.

全球油气行业留存有海量遥控水下机器人（Remotely Operated Vehicle, ROV）巡检影像档案，其中或蕴藏有关海洋生物群落的珍贵长期观测数据。随着全球油气设施退役时代的临近，评估此类影像在相关群落研究中的应用价值恰逢其时。本研究于2006年与2008年间，在澳大利亚西北陆架的古德温α生产平台（Goodwyn Alpha Production Platform, GWA）10至125米水深范围内，利用ROV巡检影像对附着于该平台的固着无脊椎动物（sessile invertebrates）与鱼类群落开展了特征刻画工作。水深是调控无脊椎动物群落组成的关键驱动因子，这大概率与光照等环境因子的特异性需求密切相关；而不同调查年份间的群落差异，则最可能源于热带气旋与内波对物种造成的物理剥离。光合营养物种（Phototrophic species）大多局限于平台上方50米水深区间，包括杯形珊瑚属（Pocillopora sp.）、穗珊瑚属（Nephthea sp.）及硬棘软珊瑚属（Scleronephthya sp.）等类群。与之相对，异养营养物种（heterotrophic species）涵盖海绵、海葵、苔藓虫、水螅虫、覆瓦牡蛎（Lopha folium）等双壳类以及筒星珊瑚属（Tubastrea spp.）等硬珊瑚，广泛分布于所有调查水深区间。本次调查共记录到1791尾鱼类，隶属于至少10个科、19个物种，包括红鳍笛鲷（crimson seaperch, Lutjanus erythropterus）、红帝王笛鲷（red emperor, Lutjanus sebae）、马拉巴笛鲷（saddle-tailed seaperch, Lutjanus malabaricus）、紫红笛鲷（mangrove jack, Lutjanus argentimaculatus）以及鲹属（trevally, Caranx spp.）等商业捕捞物种。2008年的鱼类密度随水深显著升高：10至25米区间的平均密度为23尾/50平方米，而在125米水深处，因小型未鉴定饵鱼大量聚集，密度达到3373尾/50平方米。商业捕捞物种的最高密度出现在25至75米水深区间，表明平台中层区域具备极高的栖息地价值，这一结论可为油气设施退役方案的选取提供重要参考。使用该影像资料时面临的最大挑战为光照条件不佳与分辨率不足，这限制了我们对固着无脊椎动物开展高精度分类鉴定的能力。不过，该影像档案仍可用于评估平台的整体生物多样性、解析鱼类与无脊椎动物群落随水深的变化规律，以及理解无脊椎动物群落随时间推移的动态特征。未来制定环境友好的油气设施退役决策时，充分认知设施的栖息地价值至关重要。