The influence of seabirds on their breeding, roosting, and nesting grounds: a systematic review and meta-analysis

1. Seabird species worldwide are integral to both marine and terrestrial environments, connecting the two systems by transporting vast quantities of marine-derived nutrients and pollutants to terrestrial breeding, roosting, and nesting grounds via the deposition of guano and other allochthonous inputs (e.g., eggs, feathers).
2. We conducted a systematic review and meta-analysis and provide insight into what types of nutrients and pollutants seabirds are transporting, the influence these subsidies are having on recipient environments, with a particular focus on soil, and what may happen if seabird populations decline.
3. The addition of guano to colony soils substantially increased nutrient levels compared to control soils for all seabirds studied, with cascading positive effects observed across a range of habitats. Deposited guano sometimes led to negative impacts, such a guanotrophication, or guano-induced eutrophication, which was often observed where there was an excess of guano or in areas with high seabird densities.
4. While the literature describing nutrients transported by seabirds is extensive, literature regarding pollutant transfer is comparatively limited, with a focus on toxic and bioaccumulative metals. Research on persistent organic pollutants and plastics transported by seabirds is likely to increase in coming years.
5. Studies were limited geographically, with hotspots of research activity in a few locations, but data were lacking from large regions around the world. Studies were also limited to seabird species generally listed as Least Concern on the IUCN Red List. As seabird populations are impacted by multiple threats and steep declines have been observed for many species worldwide, gaps in the literature are particularly concerning. The loss of seabirds will impact nutrient cycling at localised levels and potentially on a global scale as well, yet it is unknown what may truly happen to areas that rely on seabirds if these populations disappear.

The information in this record includes three spreadsheets and R code. Descriptions are included below:
- The spreadsheets contain all information extracted from the publications that were critically reviewed (n = 181). The first spreadsheet contains information regarding each publication (1 publication per row), such as study location, sampling methods. The second spreadsheet contains information about the seabird species studied in each publication (1 row per seabird species per publication). The third spreadsheet contains data for the meta-analysis (1 row per publication, except if the publication studied multiple species, then it would be 1 row per species per publication).
- The R code is for the meta-analyses that were undertaken. Comments are included within the code plus detailed information can be found in the Methods section of the paper.

1. 全球范围内的海鸟物种均为海洋与陆地生态系统不可或缺的组成部分，它们通过鸟粪及其他异地输入物（如卵、羽毛）的沉积，将大量海洋来源的营养物质与污染物输送至陆地繁殖、栖息与筑巢场地，从而连接两大生态系统。
2. 本研究开展了系统综述与荟萃分析，旨在阐明海鸟所输送的营养物质与污染物类型、这些输入对受纳生境的影响（重点关注土壤生境），以及海鸟种群衰退可能引发的后续变化。
3. 针对所有受试海鸟，其繁殖地土壤中添加鸟粪后，营养盐水平较对照土壤显著提升，并在多种生境中观测到级联正效应。沉积的鸟粪有时会引发负面效应，如鸟粪型富营养化（guanotrophication）或鸟粪诱导的富营养化，此类现象常出现在鸟粪过量或海鸟种群密度较高的区域。
4. 尽管有关海鸟输送营养物质的研究文献已较为丰富，但关于污染物迁移的相关研究则相对有限，且现有研究多聚焦于有毒且具有生物累积性的金属污染物。未来数年中，针对海鸟输送持久性有机污染物与塑料的相关研究有望持续增长。
5. 现有研究在地理分布上存在局限，仅少数区域形成研究热点，全球多数大型区域仍缺乏相关数据。同时，研究对象也仅局限于世界自然保护联盟红色名录（IUCN Red List）中被列为无危（Least Concern）的海鸟物种。鉴于海鸟种群正受到多重威胁，全球多数海鸟物种已出现种群数量的大幅下降，因此文献研究的空白尤为令人担忧。海鸟种群的消失将对局地营养循环产生影响，甚至可能波及全球尺度；然而，对于依赖海鸟的区域最终会发生何种变化，目前仍不得而知。

本数据集包含三张电子表格与R代码，具体说明如下：
- 电子表格涵盖了经严格评审的181篇文献中提取的全部信息。第一张电子表格单篇文献对应一行数据，内容包括研究地点、采样方法等信息。第二张电子表格记录每篇文献中涉及的受试海鸟物种信息，每篇文献对应每个物种一行数据。第三张电子表格包含荟萃分析所需数据：单篇文献对应一行数据，若文献研究多个物种时，则每个物种对应一行数据。
- R代码用于开展本次研究的荟萃分析，代码中包含注释，详细信息可参见论文的方法学部分。