Data from: Multi-parametric study of behavioural modulation in demersal decapods at the VENUS cabled observatory in Saanich Inlet, British Columbia, Canada

Understanding biological rhythms in benthic ecosystems and their modulation by habitat cycles has important implications for resource and ecosystem management. The recent development of permanent, multi-sensor seafloor observatories in deep-water environments provides opportunities for the in situ investigation of the behaviour of benthic organisms in relation to habitat variability. This paper describes a multi-disciplinary investigation at the VENUS observatory platform in Saanich Inlet, an intermittently anoxic fjord (Vancouver Island, Canada). A remotely operated digital camera (103 m depth) was used to document changes in the abundance of shrimp (Spirontocaris spp.) and the squat lobster (Munida quadrispina), as well as bacterial mat coverage (Beggiatoa spp.). These data were used as proxies of diel rhythms related to day–night and internal tidal cycles. Seafloor photos were acquired hourly during consecutive days, before, during and after oxygen intrusion events in the fall of 2009. In order to relate biological fluctuations to habitat cycles, bottom water pressure, temperature, dissolved oxygen, and nitrate data were also acquired from the observatory database. Periodogram analysis showed a weak internal-tide-associated rhythmicity for Spirontocaris spp. that was absent in M. quadrispina and in bacterial mat coverage. Waveform analysis confirmed the absence of any day–night fluctuation in all tested species. However, a rapid intrusion of oxygenated water at the study site influenced visual counts of species, possibly blurring detectable activity rhythms. Temperature and nitrate fluctuations were more accentuated during spring tides but cross-correlation analysis indicated an absence of species responses to these habitat variables. Results are discussed within the context of the complex oceanographic dynamics of Saanich Inlet and with respect to understanding the ecological consequences of expanding hypoxia in the global ocean.

解析底栖生态系统（benthic ecosystems）中的生物节律及其受生境周期的调控机制，对资源管理与生态系统保护具有重要意义。近年来深水海域固定式多传感器海底观测站的发展，为原位（in situ）探究底栖生物行为与生境变化之间的关联提供了可能。本研究针对加拿大温哥华岛萨尼奇湾（Saanich Inlet，间歇性缺氧峡湾）内的VENUS观测平台（VENUS observatory platform）开展了一项多学科调查。研究采用部署于103米水深的遥控数码相机，记录了虾类（俪虾属*Spirontocaris* spp.）、四刺铠甲虾（*Munida quadrispina*）的丰度变化，以及贝氏硫菌属（*Beggiatoa* spp.）菌席的覆盖度。上述数据被用作表征与昼夜交替及内潮汐周期相关的日节律（diel rhythms）的替代指标。2009年秋季，在含氧水入侵事件的前、中、后阶段，研究人员连续多日每小时采集一次海底图像。为了将生物波动与生境周期相关联，研究人员同时从观测平台数据库中获取了底层海水压力、温度、溶解氧及硝酸盐浓度数据。周期图分析（periodogram analysis）结果显示，俪虾属*Spirontocaris* spp.存在较弱的内潮汐相关节律，而四刺铠甲虾与贝氏硫菌菌席则未表现出该节律。波形分析（waveform analysis）证实，所有受试类群均未出现昼夜波动。然而，研究区域内含氧水的快速入侵会影响物种的视觉计数结果，可能掩盖了可被检测到的活动节律。大潮（spring tides）期间海水温度与硝酸盐浓度波动更为显著，但互相关分析（cross-correlation analysis）结果显示，受试物种并未对这些生境变量产生响应。本研究结合萨尼奇湾复杂的海洋动力学背景，以及全球海洋缺氧范围扩张的生态效应研究背景，对上述结果展开了讨论。