López-Calderón Cosme, Martín-Vélez Víctor, Blas Julio, Höfle Ursula, Sánchez Marta I, Flack Andrea, Fiedler Wolfgang, Wikelski Martin, Green Andy J
Department of Wetland Ecology, Estación Biológica de Doñana CSIC, Seville, Spain.
Department of Conservation Biology, Estación Biológica de Doñana CSIC, Seville, Spain.
Mov Ecol. 2023 Mar 28;11(1):18. doi: 10.1186/s40462-023-00380-7.
Connections between habitats are key to a full understanding of anthropic impacts on ecosystems. Freshwater habitats are especially biodiverse, yet depend on exchange with terrestrial habitats. White storks (Ciconia ciconia) are widespread opportunists that often forage in landfills and then visit wetlands, among other habitats. It is well known that white storks ingest contaminants at landfills (such as plastics and antibiotic resistant bacteria), which can be then deposited in other habitats through their faeces and regurgitated pellets.
We characterized the role of white storks in habitat connectivity by analyzing GPS data from populations breeding in Germany and wintering from Spain to Morocco. We overlaid GPS tracks on a land-use surface to construct a spatially-explicit network in which nodes were sites, and links were direct flights. We then calculated centrality metrics, identified spatial modules, and quantified overall connections between habitat types. For regional networks in southern Spain and northern Morocco, we built Exponential Random Graph Models (ERGMs) to explain network topologies as a response to node habitat.
For Spain and Morocco combined, we built a directed spatial network with 114 nodes and 370 valued links. Landfills were the habitat type most connected to others, as measured by direct flights. The relevance of landfills was confirmed in both ERGMs, with significant positive effects of this habitat as a source of flights. In the ERGM for southern Spain, we found significant positive effects of rice fields and salines (solar saltworks) as sinks for flights. By contrast, in the ERGM for northern Morocco, we found a significant positive effect of marshes as a sink for flights.
These results illustrate how white storks connect landfills with terrestrial and aquatic habitats, some of which are managed for food production. We identified specific interconnected habitat patches across Spain and Morocco that could be used for further studies on biovectoring of pollutants, pathogens and other propagules.
栖息地之间的联系是全面理解人类活动对生态系统影响的关键。淡水栖息地生物多样性尤其丰富，但依赖与陆地栖息地的交换。白鹳（Ciconia ciconia）是分布广泛的机会主义者，经常在垃圾填埋场觅食，然后前往湿地等其他栖息地。众所周知，白鹳在垃圾填埋场摄入污染物（如塑料和抗生素抗性细菌），这些污染物随后可通过它们的粪便和反刍的颗粒沉积在其他栖息地。
我们通过分析来自德国繁殖种群以及从西班牙到摩洛哥越冬种群的GPS数据，来确定白鹳在栖息地连通性中的作用。我们将GPS轨迹叠加在土地利用表面上，构建一个空间明确的网络，其中节点为地点，链接为直飞航线。然后我们计算中心性指标，识别空间模块，并量化栖息地类型之间的整体联系。对于西班牙南部和摩洛哥北部的区域网络，我们构建了指数随机图模型（ERGM）来解释网络拓扑结构如何响应节点栖息地。
对于西班牙和摩洛哥的组合区域，我们构建了一个有向空间网络，有114个节点和370条加权链接。通过直飞航线衡量，垃圾填埋场是与其他栖息地联系最紧密的栖息地类型。在两个ERGM中都证实了垃圾填埋场的重要性，该栖息地作为飞行源具有显著的积极影响。在西班牙南部的ERGM中，我们发现稻田和盐田（太阳能盐场）作为飞行目的地具有显著的积极影响。相比之下，在摩洛哥北部的ERGM中，我们发现沼泽作为飞行目的地具有显著的积极影响。
这些结果说明了白鹳如何将垃圾填埋场与陆地和水生生境联系起来，其中一些生境是为粮食生产而管理的。我们确定了西班牙和摩洛哥境内特定的相互连接的栖息地斑块，可用于进一步研究污染物、病原体和其他繁殖体的生物传播。
