Blue whale foraging and movement ecology

This archive contains data used in a study of the movement and foraging ecology of blue whales in the eastern North Pacific, specifically the Monterey Bay region off central California, USA.  The study was published in Ecology Letters in 2022 and is entitled, “Oceanic giants dance to atmospheric rhythms: Ephemeral wind-driven resource tracking by blue whales.”  As of this writing, the article does not yet have a DOI.  

The published analyses were conducted in MATLAB.  However, to make the data and reproducibility of analyses more widely accessible, both data and processing code have been translated into R for this archive.

1) Acoustic vector sensor (AVS) data from the MARS observatory

Annual periods of blue whale acoustic presence were analyzed across two years to examine the directional distribution of whale call origin around the MARS cabled observatory.  Quality controlled data include the time, bearing, and call index of all manually validated seconds for which the blue whale B-call index exceeded a value of 1.25.  Analysis results from these data appear in Figures 4 and 5 of the paper.  The data files are AVS_2019-2020.RData and AVS_2020-2021.RData, and the example processing code is AVSprocessing.R.

2) Modeled received levels at the MARS observatory

The geographic domain over which received signal is sufficient to reliably estimate the direction of blue whale B-call origin from the MARS cabled observatory was approximated by modeling of acoustic transmission loss.  These data appear in Figure 2C of the paper.  Model results represent received level (underwater dB) at the MARS cabled observatory, assuming appropriately specified intensity, depth, and frequency of the sound source (blue whale B call) and oceanographic physical conditions during the time of year when blue whale calling is most active in the study region.  The data file is ModeledReceivedLevel.RData, and the example processing code is ModeledReceivedLevelPlot.R.

3) Animal-borne tag data

Data from a biologging tag deployed on a blue whale were used to validate an acoustic vector sensor on the MARS observatory.  These data appear in Figure 3 of the paper and include information about whale behaviors (diving, calling, lunge feeding) and surface position from GPS.  In addition to data on identified behavioral events, underlying hydrophone and accelerometer data used to identify behaviors during the period of matchup with MARS AVS data are included.  The data file is Tag_bw191101-70.RData, and the example processing code is Tag_bw191101-70plot.R.

4) Forage species aggregation data

The area scattering (sa) within forage species’ patches in the upper 200 m above the MARS observatory, presented in Figure 5E of the paper, are in the file MARS_sa.RData.

本存档包含了一项针对北太平洋东部（尤其是美国加利福尼亚州中部近海蒙特雷湾海域）蓝鲸的运动与觅食生态学研究所用的数据。该研究于2022年发表于《Ecology Letters》期刊，论文标题为《海洋巨物随大气节律起舞：蓝鲸对风驱动的短暂资源的追踪行为》。截至本文撰写时，该论文尚未获取数字对象标识符（DOI）。

已发表的分析工作原采用MATLAB完成。为提升数据与分析可复现性的普适性，本存档同时提供了转换为R语言的数据集与处理代码。

1) MARS观测站声学矢量传感器（Acoustic Vector Sensor, AVS）数据
本研究对两年内蓝鲸声学出现的年度时段展开分析，以探究MARS缆接式观测站周边蓝鲸鸣唱声源的方位分布特征。经过质量管控的数据包含所有经人工核验的秒级记录的时间、方位角与鸣唱指数，且蓝鲸B型鸣唱指数均高于1.25。基于该数据集的分析结果见论文图4与图5。相关数据文件为AVS_2019-2020.RData与AVS_2020-2021.RData，示例处理代码为AVSprocessing.R。

2) MARS观测站模拟接收声级数据
通过声学传输损耗建模，本研究近似得到了可通过MARS缆接式观测站可靠估算蓝鲸B型鸣唱声源方位的有效信号接收地理范围。该数据集见论文图2C。模型结果为：假设声源（蓝鲸B型鸣唱）的强度、深度与频率设置合理，且研究区域内蓝鲸鸣唱最活跃时段的海洋物理条件符合实际时，MARS缆接式观测站处的接收声级（水下分贝）。相关数据文件为ModeledReceivedLevel.RData，示例处理代码为ModeledReceivedLevelPlot.R。

3) 动物搭载式生物记录标记（biologging tag）数据
本研究使用部署于蓝鲸体表的生物记录标记数据，对MARS观测站的声学矢量传感器进行了校准验证。该数据集见论文图3，包含蓝鲸的行为信息（潜水、鸣唱、冲刺摄食）以及基于GPS获取的水面位置数据。除已识别的行为事件数据外，本存档还包含了用于匹配MARS AVS数据时段内行为识别的原始水听器与加速度计数据。相关数据文件为Tag_bw191101-70.RData，示例处理代码为Tag_bw191101-70plot.R。

4) 饵料物种集群数据
本研究中呈现于论文图5E的MARS观测站上方200米水层内饵料物种斑块的面积散射系数（area scattering, sa）数据，存储于文件MARS_sa.RData中。