Combined bottom‐up and top‐down pressures drive catastrophic population declines of Arctic skuas in Scotland
Combined bottom‐up and top‐down pressures drive catastrophic population declines of Arctic skuas in Scotland
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自下而上和自上而下的共同压力导致苏格兰北极贼鸥数量灾难性下降
DOI：
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发表时间：
2018
影响因子：
4.8
通讯作者：
M. Bolton
中科院分区：
文献类型：
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作者：
A. Perkins;N. Ratcliffe;D. Suddaby;B. Ribbands;Claire L. Smith;Pete Ellis;E. Meek;M. Bolton
了解种群变化的驱动因素对于有效的物种保护至关重要。在大西洋东北部，海鸟群落最近的变化与人类和气候变化对食物网的影响有关。由于食物短缺和捕食增加降低了生产力，许多物种数量严重减少。北极贼鸥（Stercorarius parasiticus）是其他海鸟的盗贼寄生虫，就是这样的一个物种。该研究的目的是确定在国家人口迅速减少的情况下，自下而上和自上而下的压力对多个栖息地的北极贼鸥的相对影响。长期监测数据用于量化北极贼鸥、它们的宿主（黑腿三趾鸥 Rissa tridactyla、海鸠 Uria aalge、大西洋海雀 Fratercula arctica、北极燕鸥 Sterna paradisaea）和顶级捕食者（大贼鸥 Stercorarius skua）在 24 年来的种群规模和生产力变化（1992-2015）在苏格兰。我们使用数字测绘和统计模型来确定自下而上（寄主生产力）和自上而下（大贼鸥密度）压力对 33 个北极贼鸥栖息地的相对影响，并评估按寄主丰度分类的三种群落类型之间的差异。北极贼鸥数量减少了 81%，它们的寄主数量减少了 42%-92%，而大多数栖息地的大贼鸥数量有所增加。北极贼鸥及其寄主的年生产力下降，北极贼鸥繁殖成功率的下降是该物种数量下降的一个驱动因素。北极贼鸥的生产力与宿主每年的繁殖成功率呈正相关，与贼鸥的密度呈负相关。群体间的变化表明，北极贼鸥的趋势和生产力对较小的寄主物种群体的自上而下的压力最敏感，其中大贼鸥增加最多，而自下而上的压力在大型寄主物种群体中占主导地位。苏格兰的北极贼鸥数量正在迅速减少，自下而上和自上而下的压力同时将繁殖成功率降低到不可持续的低水平。受渔业管理和气候变化的强烈影响，海洋食物网的改变正在推动海鸟数量的下降，这项研究表明，海鸟对人类改变的生态系统的快速变化非常脆弱。针对北极贼鸥的潜在但未经测试的保护解决方案包括海洋保护区、群体内的补充喂养以及大贼鸥的管理。
Understanding drivers of population change is critical for effective species conservation. In the northeast Atlantic Ocean, recent changes amongst seabird communities are linked to human and climate change impacts on food webs. Many species have declined severely, with food shortages, and increased predation reducing productivity. Arctic skua Stercorarius parasiticus, a kleptoparasite of other seabirds, is one such species. The aim of the study was to determine relative effects of bottom-up and top-down pressures on Arctic skuas across multiple colonies in a rapidly declining national population. Long-term monitoring data were used to quantify changes in population size and productivity of Arctic skuas, their hosts (black-legged kittiwake Rissa tridactyla, common guillemot Uria aalge, Atlantic puffin Fratercula arctica, Arctic tern Sterna paradisaea) and an apex predator (great skua Stercorarius skua) over 24 years (1992-2015) in Scotland. We used digital mapping and statistical models to determine relative effects of bottom-up (host productivity) and top-down (great skua density) pressures on Arctic skuas across 33 colonies, and assess variation between three colony types classified by host abundance. Arctic skuas declined by 81% and their hosts by 42%-92%, whereas at most colonies great skuas increased. Annual productivity declined in Arctic skuas and their hosts, and reduced Arctic skua breeding success was a driver of the species' population decline. Arctic skua productivity was positively associated with annual breeding success of hosts and negatively with great skua density. Intercolony variation suggested Arctic skua trends and productivity were most sensitive to top-down pressures at smaller colonies of host species where great skuas had increased most, whereas bottom-up pressures dominated at large colonies of host species. Scotland's Arctic skua population is declining rapidly, with bottom-up and top-down pressures simultaneously reducing breeding success to unsustainably low levels. Marine food web alterations, strongly influenced by fisheries management and climate change, are driving the decline, and this study demonstrates severe vulnerability of seabirds to rapid change in human-modified ecosystems. Potential but untested conservation solutions for Arctic skuas include marine protected areas, supplementary feeding within colonies and management of great skuas.