Linking Predator-Prey Dynamics: Spatiotemporal Trends in Marine Predation Around Shetland

理解种群动态的驱动因素是纯生态学和应用生态学的一个基本问题。对于海洋顶级捕食者来说，量化猎物可获得性所起的作用，对于评估当前和计划中的人类活动的潜在影响，从而对生态系统的环境可持续管理至关重要。然而，由于缺乏适当分辨率的猎物数据，这类研究受到限制，导致研究人员不得不主要依靠分辨率较低的猎物数据(国际海洋探索理事会；datras.ices.dk)或环境协变量作为衡量猎物可用性的指标。缺乏数据也阻碍了近岸鱼类种群的有效管理。设得兰得益于一套在英国独一无二的数据集(都可用于该项目)，这将允许探索顶级捕食者和鱼类内部和之间的时空关系。此外，设得兰是一个具有养护和管理价值的地区；它拥有大量鱼类多样性和捕食者物种，同时支持高水平和不断增加的海洋资源获取。设得兰有专门的近海鱼类调查(2011年起每年一次；SuHI)。此外，还有SANDEL历史数据(1974-1999年)。对于海鸟，有繁衍丰度的数据，以及40多年来设得兰周围的每月海滩鸟类调查，测量海鸟身体和石油污染率(SOTEAG，海鸟监测计划&RSPB)，产生了英国最全面的海鸟丰度数据集之一。这些数据被广泛的跟踪数据集(七个物种；RSPB)所增强。此外，SMRU还保存着海豹捕捞数量、饮食和跟踪数据。这些数据显示了整个设得兰地区鱼、海鸟和海豹丰度趋势的鲜明物种和地区差异。例如，设得兰港海豹的数量在2001至2015年间下降了约40%，在那次下降前后数量保持稳定。然而，围绕两个(海豹)囊的区域呈现出截然不同的趋势；耶尔湾趋势反映了整个设得兰地区的趋势，但设得兰东南部(包括Mousa SAC)自20世纪90年代初以来一直显示出持续的下降。缺乏对多个物种和营养水平的长期种群趋势的研究。对顶级捕食者趋势的比较分析可以阐明变化的驱动因素。事实上，觅食可塑性有限的物种种群对猎物可获得性的减少更加敏感。

Understanding the drivers of population dynamics is a fundamental question in both pure and applied ecology. For marine top predators quantifying the role that prey availability plays is critical in evaluating the potential impacts of current and planned human activities, and thus for environmentally sustainable management of the ecosystem. However, such research has been limited by a lack of prey data at an appropriate resolution, resulting in researchers primarily having to rely on coarse resolution prey data (International Council for the Exploration of the Sea; datras.ices.dk) or environmental covariates as proxies for prey availability. Such a lack of data has also hampered effective management of inshore fish stocks. Shetland benefits from a set of datasets (all available for this project), unique in the UK, that would allow exploration of the spatiotemporal relationship within and between top predators and fish. Moreover, Shetland is an area of conservation and management interest; it hosts significant fish diversity and populations of predator species while supporting high and increasing levels of marine resource acquisition. Shetland has a dedicated inshore fish survey (annual from 2011; SUHI). In addition, there are historic sandeel data (1974-1999). For seabirds, there are breeding abundance data, and a monthly beached bird survey measuring seabird corpse and oil pollution rates, from around Shetland for over four decades (SOTEAG, Seabird Monitoring Program & RSPB), resulting in one of the UK's most comprehensive datasets on seabird abundance. These data are augmented by extensive tracking datasets (seven species; RSPB). Furthermore, SMRU hold data on seal haulout abundance, diet and tracking data. These data show stark species and regional variation across Shetland in trends in abundance of fish, seabirds and seals. For example, the Shetland harbour seal population fell by ~ 40% between 2001 and 2015 with stable abundance prior to and following that fall. However, the areas encompassing the two (harbour seal) SACs show contrasting trend; the Yell Sound trend mirrors the Shetland-wide trend but southeast Shetland (includes Mousa SAC), has shown a continuing decline since the early 1990s. There is a lack of studies of long-term population trends across multiple species and trophic levels. Comparative analyses of trends of top predators can elucidate the drivers of change. Indeed, populations of species with a limited foraging plasticity are more sensitive to reduced prey availability.