Fish use of deep-sea sponge habitats revealed by long-term, high-resolution monitoring

In this study, we used long-term high-temporal resolution data to gain insights into the functional use of the Sambro Bank Conservation Sponge Grounds by fish. In particular, we aimed at capturing fish behaviour and complex benthopelagic interactions over spatial and extended temporal scales (i.e. 30-minute intervals for 2-8 months, in two separate time periods through 2021-2023). To achieve this, an integrated ecosystem-based monitoring approach was used, involving data collected on the biology (time-lapse image cameras, telemetry, Chl a, video and trawl surveys), food supply (sediment traps), and oceanography (temperature, salinity, current speed and direction). Random forest models, along with time-series analytical approaches, were used to determine what drives the observed spatial and temporal differences in fish occurrences. A total of 21 different planktivorous and benthivorous fish taxa were found utilising the seafloor. We provide the first evidence that sponge grounds are utilised as nurseries by Redfish, urophycid hakes, Silver Hake, and American Plaice. Distinct diel and seasonal patterns were found. Our results also indicated that food availability, sponge density and current speeds are associated with the presence and behaviour of some juvenile and adult fish. We demonstrated that a high temporal resolution ecosystem monitoring approach, in combination with other data types, is essential for understanding how benthic habitats and environmental drivers impact valued natural resources. Such information is crucial for developing and implementing robust, evidence-based policy and management decisions.本研究采用长期高时间分辨率数据集，解析鱼类对桑布罗海床保护海绵栖息地（Sambro Bank Conservation Sponge Grounds）的功能性利用模式。具体而言，本研究旨在观测空间与长期时间尺度下的鱼类行为及复杂底中水层相互作用，即于2021-2023年的两个独立时段内，以30分钟为间隔开展为期2至8个月的监测。为达成该研究目标，本研究采用基于生态系统的整合监测方案，涵盖多类数据：生物学数据（延时影像相机、遥测技术、叶绿素a（Chl a）、视频记录与拖网调查）、食物供给数据（沉积物捕集器）以及海洋学数据（温度、盐度、海流速度与方向）。本研究运用随机森林模型与时间序列分析方法，探究驱动鱼类出现情况呈现时空差异的核心因子。本次调查共计发现21种不同的浮游食性与底栖食性鱼类类群栖息于该海底区域。本研究首次提供实证证据，表明海绵栖息地被红鱼（Redfish）、鼬鳕类（urophycid hakes）、银无须鳕（Silver Hake）以及美洲鲽（American Plaice）用作育苗场。研究结果显示存在显著的昼夜与季节活动模式。同时，本研究结果表明，食物可获得性、海绵群落密度与海流速度与部分幼鱼及成鱼的栖息状态及行为模式存在显著关联。本研究证实，高时间分辨率生态系统监测方法结合多类型数据，是解析底栖生境与环境驱动因子如何影响珍贵自然资源的必要手段。此类信息对于制定并落实严谨且循证的政策与管理决策至关重要。