Data from: Behavioral response of a mobile marine predator to environmental variables differs across ecoregions

Animal movement and habitat selection are in part a response to landscape
heterogeneity. Many studies of movement and habitat selection necessarily
use environmental covariates that are readily available over large‐scales,
which are assumed representative of functional habitat features such as
resource availability. For widely distributed species, response to such
covariates may not be consistent across ecosystems, as response to any
specific covariate is driven by its biological relevance within the
context of each ecosystem. Thus, the study of any widely distributed
species within a limited geographic region may provide inferences that are
not widely generalizable. Our goal was to evaluate the response of a
marine predator to a suite of environmental covariates across a wide
ecological gradient. We identified two behavioral states (resident and
transient) in the movements of shortfin mako sharks (Isurus oxyrinchus)
tracked via satellite telemetry in two regions of the western North
Atlantic Ocean: the tropical Caribbean/Gulf of Mexico marginal sea (CGM),
and the temperate waters off the east coast of North America (OWA). We
compared patterns of resident behavior between regions, and modeled
relationships between oceanographic variables and resident behavior. We
tracked 39 sharks during 2013 – 2015. Resident behavior was associated
with shallow, continental shelf and slope waters in both regions. In the
OWA resident behavior was associated with low sea surface temperature and
high primary productivity, however, sharks exhibited no response to either
variable in the CGM. There was a negative relationship between sea‐surface
height gradient (a proxy for oceanic fronts) and resident behavior in the
OWA, and a positive relationship in the CGM. Our observations likely
reflect shark responses to regional variability in factors responsible for
the distribution and availability of prey. Our study illustrates the
importance of studying widely distributed species in a consistent manner
over large spatial scales.

动物的移动与生境选择，在一定程度上是对景观异质性的响应。诸多针对移动与生境选择的研究，必然会采用可在大空间尺度上便捷获取的环境协变量，并假定这些变量可表征诸如资源可获得性等功能性生境特征。对于广布物种而言，其对这类协变量的响应在不同生态系统中可能并不一致，因为对某一特定协变量的响应，取决于该变量在对应生态系统背景下的生物学相关性。因此，仅在有限地理区域内开展的广布物种研究，其得出的推论未必具备广泛的可推广性。本研究旨在评估某一海洋捕食者在宽泛生态梯度下对一系列环境协变量的响应。我们针对西北大西洋两处海域内通过卫星遥测（satellite telemetry）追踪的短鳍鲭鲨（Isurus oxyrinchus）的移动轨迹，识别出两种行为状态：定居型（resident）与漫游型（transient）。两处海域分别为热带加勒比海/墨西哥湾边缘海（CGM），以及北美东海岸外的温带海域（OWA）。我们对比了不同区域内定居行为的模式，并构建了海洋学变量与定居行为之间的关系模型。本研究在2013至2015年间共追踪了39条短鳍鲭鲨。在两处海域中，定居行为均与浅水区、大陆架及陆坡海域相关联。在OWA海域，定居行为与低海表面温度（sea surface temperature, SST）及高初级生产力（primary productivity）相关；但在CGM海域，鲨鱼并未对这两类变量表现出任何响应。在OWA海域，海表面高度梯度（sea-surface height gradient）作为海洋锋面（oceanic fronts）的替代指标，与定居行为呈负相关关系；而在CGM海域则呈正相关关系。本研究的观测结果大概率反映了鲨鱼对调控猎物分布与可获得性的区域变量的响应。本研究也阐明了，在大空间尺度上采用统一方法开展广布物种研究的重要性。