Surveys of the ecological use of epibenthic habitat by fish in the central Great Barrier Reef using baited remote underwater video stations (BRUVS (TM)) (FRDC Project No. 97/205)

BRUVS (TM) were deployed at spatial coordinates known, from previous major studies using fish traps, to be "hot-spots" for the families Lutjanidae (sea perches), Lethrinidae (sweetlip emperors) and Serranidae (coral trout and cod).BRUVS (TM) were deployed at depths between 30 and 70 m in three mid-shelf locations (Davies Reef (9), Kelso Shoals (18), Rib Reef (9)) and in both shallow and deep inshore locations (Calliope Channel (14), Curacoa Channel (27), and Robbery Shoals (3)).Replicate BRUVS (TM), were deployed in daylight hours and the time, depth, latitude and longitude was recorded for each set.Interrogation of each tape provided:- a classification of the habitat at each set, based on estimated sediment composition and/or the nature of epibenthos- the time the BRUVS (TM) settle on the seabed (TOB)- the time of first sighting of a taxa (TFS)- a coarse classification of 'Adult' or 'Juvenile' for these taxa based on size and shape- the time of first feeding of taxa (TFF) in the field of view,- the maximum number of each taxa seen together, or readily identifiable, in any one time on the whole tape (MaxN),- the time at which this maxima occurred (TMaxN)- the behaviour of each taxa toward the bait (passing, scavenging, or feeding), and- the time at which all bait was exhausted if such an event occurred.The habitat categories recognised were: megabenthos, Sargassum, Halimeda, low algae, mud, fine sand, coarse sand, rubble, and 'near benthos'. The 'near benthos' category covered sets where video units landed on sand, but in the far field of view, or during the deployment or retrieval, significant patches of rock or megabenthos were seen.Image grabs also allowed size estimates of fish directly above the scale grid on the bait canister.
Baited remote underwater video station (BRUVS (TM)) surveys were undertaken to investigate the relationship between fish requirements for food and shelter and the distribution of sponge, gorgonian and algal 'megabenthos'.The specific questions addressed were:1. what is the nature of fish communities inside and outside megabenthos patches?2. what benthos and sediments characterise some known 'hotspots' for inter-reef lutjanids?The results of the BRUVS (TM) surveys were compared with concurrent RUVS (unbaited) surveys, trapping and underwater visual census (UVC) as methods to census demersal fish.
This research was a component of subproject 8, "The ecological usage of epibenthic habitat by key commercial finfish species", of the Fisheries Research and Development Corporation Project No. 97/205, "Dynamics of large sessile seabed fauna, important for structural fisheries habitat and biodiversity of marine ecosystems - and use of these habitats by key finfish species"

诱饵远程水下视频站（Baited Remote Underwater Video Station, BRUVS (TM)）被布设至此前利用鱼笼开展的大型研究中确定的空间坐标处，这些区域是笛鲷科（Lutjanidae，海鲈）、裸颊鲷科（Lethrinidae，甜唇龙占）以及鮨科（Serranidae，珊瑚鳟与石斑）的"热点海域"。BRUVS (TM) 的布设水深为30至70米，涵盖3个陆架中部站位：戴维斯礁（Davies Reef，9次布设）、凯尔索浅滩（Kelso Shoals，18次布设）与里夫礁（Rib Reef，9次布设）；同时覆盖近岸的浅水区与深水区：卡利奥普海峡（Calliope Channel，14次布设）、库拉科阿海峡（Curacoa Channel，27次布设）以及罗比浅滩（Robbery Shoals，3次布设）。重复布设的BRUVS (TM) 均在日间开展作业，且记录了每次布设的时间、水深、纬度与经度。对每段录像进行解析后可获得以下信息：基于估算的沉积物组成以及/或者底上生物（epibenthos）特征的各布设点生境分类；BRUVS (TM) 落座于海床的时间（TOB）；某一分类群首次被观测到的时间（TFS）；基于体型与形态的该分类群成体/幼体粗分类；视野内某分类群首次进食的时间（TFF）；整段录像中任意时刻同时出现、可清晰辨识的各分类群最大个体数（MaxN）；该最大个体数出现的时间（TMaxN）；各分类群对诱饵的行为模式（途经、食腐或进食）；若诱饵被完全耗尽，记录该事件发生的时间。本次研究采用的生境分类类别包括：大型底栖生物（megabenthos）、马尾藻（Sargassum）、仙掌藻（Halimeda）、低矮藻类、泥质、细沙、粗沙、碎石以及"近底生境"。其中"近底生境"类别涵盖了录像装置落在沙地上，但在远场视野中，或在部署/回收阶段可见大量岩石或大型底栖生物斑块的布设点。此外，通过图像抓取还可对诱饵罐刻度网格正上方的鱼类进行体型估算。诱饵远程水下视频站（BRUVS (TM)）调查旨在探究鱼类对食物与庇护场所的需求，与海绵、柳珊瑚以及藻类"大型底栖生物"分布之间的关联。本调查旨在解答两个具体问题：1. 大型底栖生物斑块内外的鱼类群落具有怎样的特征？2. 已知的礁间笛鲷科鱼类"热点海域"具有哪些特征性的底栖生物与沉积物？本次BRUVS (TM) 调查结果，与同期开展的无诱饵远程水下视频站（RUVS）调查、拖网捕捞以及水下目视普查（Underwater Visual Census, UVC）这几种底层鱼类普查方法进行了对比。本研究是渔业研究与发展公司（Fisheries Research and Development Corporation）项目编号97/205"大型固着海底动物群落动态——这类动物作为渔业结构性栖息地的重要组成部分，对海洋生态系统的生物多样性具有关键意义，同时关键经济鳍鱼类物种也会利用这些栖息地"下属子项目8"关键经济鳍鱼类物种对底上生境的生态利用"的组成部分。