Data from: Quantifying pursuit-diving seabirds' associations with fine-scale physical features in tidal stream environments

The rapid increase in the number of tidal stream turbine arrays will create novel and unprecedented levels of anthropogenic activity within habitats characterized by horizontal current speeds exceeding 2 ms−1. However, the potential impacts on pursuit-diving seabirds exploiting these tidal stream environments remain largely unknown. Identifying similarities between the fine-scale physical features (100s of metres) suitable for array installations, and those associated with foraging pursuit-diving seabirds, could identify which species are most vulnerable to either collisions with moving components, or displacement from these installations. A combination of vessel-based observational surveys, Finite Volume Community Ocean Model (FVCOM) outputs, and hydroacoustic seabed surveys provided concurrent measures of foraging distributions and physical characteristics at a fine temporal (15 min) and spatial (500 m) resolution across a tidal stream environment suitable for array installations, during both breeding and non-breeding seasons. These data sets were then used to test for associations between foraging pursuit-diving seabirds (Atlantic puffins Fratercula arctica, black guillemots Cepphus grylle, common guillemots Uria aalge, European shags Phalacrocorax aristotelis) and physical features. These species associated with areas of fast horizontal currents, slow horizontal currents, high turbulence, downward vertical currents and also hard-rough seabeds. The identity and strength of associations differed among species, and also within species between seasons, indicative of interspecific and intraspecific variations in habitat use. However, Atlantic puffins were associated particularly strongly with areas of fast horizontal currents during breeding seasons, and European shags with areas of rough-hard seabeds and downward vertical currents during non-breeding seasons. Synthesis and applications. Atlantic puffins’ strong association with fast horizontal current speeds indicates that they are particularly likely to interact with installations during breeding seasons. Any post-installation monitoring and mitigation measures should therefore focus on this species and season. The multi-species associations with high turbulence and downward vertical currents, which often coincide with fast horizontal current speeds, also highlight useful pre-installation mitigation measures via the omission of devices from these areas; reducing the overall likelihood of interactions. Environmental impact assessments (EIA) generally involve once-a-month surveys across two year periods. However, the approaches used in this study show that more focussed surveys can greatly benefit management strategies aiming to reduce the likelihood of negative impacts by facilitating the development of targeted mitigation measures. It is therefore recommended that these approaches contribute towards EIA within development sites.

随着潮汐流涡轮机阵列（tidal stream turbine arrays）数量的快速增长，水平流速超过2 m·s⁻¹的海洋栖息地内的人为活动将达到前所未有的新高度。然而，此类潮汐流环境中以追击潜水方式觅食的海鸟所受的潜在影响，目前仍不明晰。识别适用于涡轮机阵列布设的精细尺度物理特征（数百米级），与追击潜水海鸟觅食相关的物理特征之间的相似性，或可明确哪些物种最易与涡轮机运动组件发生碰撞，或是被此类设施驱离原栖息觅食区域。本研究结合船舶搭载观测调查、有限体积公用海洋模型（Finite Volume Community Ocean Model, FVCOM）输出结果以及水声海底勘测数据，在适用于涡轮机阵列布设的潮汐流环境中，于繁殖季与非繁殖季两个时段，以精细的时间分辨率（15分钟）和空间分辨率（500米），同步获取了海鸟觅食分布与物理环境特征的相关数据。随后利用上述数据集，检验了追击潜水海鸟与物理环境特征之间的关联，涉及的物种包括大西洋角嘴海雀（Fratercula arctica）、黑海雀（Cepphus grylle）、普通海雀（Uria aalge）以及欧洲鸬鹚（Phalacrocorax aristotelis）。研究发现，上述物种均与快速水平流区、缓流区、高湍流区、下降垂直流区以及硬质粗糙海底存在关联。物种间的关联类型与强度存在差异，同一物种在不同季节的关联模式也有所不同，这表明不同物种间以及同一物种不同种群间的栖息地利用模式存在变异。不过，大西洋角嘴海雀在繁殖季与快速水平流区的关联尤为紧密，而欧洲鸬鹚在非繁殖季则与硬质粗糙海底及下降垂直流区存在更强关联。综合与应用：大西洋角嘴海雀与快速水平流区的强关联表明，其在繁殖季与涡轮机设施发生交互的概率极高。因此，任何设施安装后的监测与缓解措施，都应重点关注该物种与该时段。多物种与高湍流区、下降垂直流区存在关联，而此类区域往往与快速水平流区重合，这也为安装前的缓解措施提供了可行思路：可通过避开此类区域布设设备，整体降低海鸟与设施发生交互的可能性。环境影响评估（Environmental Impact Assessment, EIA）通常采用两年周期内每月一次的调查方案。但本研究采用的方法表明，更具针对性的调查可极大助力旨在降低负面影响的管理策略，通过推动针对性缓解措施的制定。因此，建议将此类方法应用于开发场地的环境影响评估工作中。