Coastal wetlands, such as saltmarshes and mangroves that fringe transitional waters, deliver important ecosystem services that support human development. Coastal wetlands are complex social-ecological systems that occur at all latitudes, from polar regions to the tropics. This overview covers wetlands in five continents. The wetlands are of varying size, catchment size, human population and stages of economic development. Economic sectors and activities in and around the coastal wetlands and their catchments exert multiple, direct pressures. These pressures affect the state of the wetland environment, ecology and valuable ecosystem services. All the coastal wetlands were found to be affected in some ways, irrespective of the conservation status. The main economic sectors were agriculture, animal rearing including aquaculture, fisheries, tourism, urbanization, shipping, industrial development and mining. Specific human activities include land reclamation, damming, draining and water extraction, construction of ponds for aquaculture and salt extraction, construction of ports and marinas, dredging, discharge of effluents from urban and industrial areas and logging, in the case of mangroves, subsistence hunting and oil and gas extraction. The main pressures were loss of wetland habitat, changes in connectivity affecting hydrology and sedimentology, as well as contamination and pollution. These pressures lead to changes in environmental state, such as erosion, subsidence and hypoxia that threaten the sustainability of the wetlands. There are also changes in the state of the ecology, such as loss of saltmarsh plants and seagrasses, and mangrove trees, in tropical wetlands. Changes in the structure and function of the wetland ecosystems affect ecosystem services that are often underestimated. The loss of ecosystem services impacts human welfare as well as the regulation of climate change by coastal wetlands. These cumulative impacts and multi-stressors are further aggravated by indirect pressures, such as sea-level rise.

The PREDICTS project—Projecting Responses of Ecological Diversity In Changing Terrestrial Systems (https://www.nhm.ac.uk/our-science/our-work/biodiversity/predicts.html)—has collated from published studies a large, reasonably representative database of comparable samples of biodiversity from multiple sites that differ in the nature or intensity of human impacts relating to land use. We have used this evidence base to develop global and regional statistical models of how local biodiversity responds to these measures. We describe and make freely available this 2016 release of the database, containing more than 3.2 million records sampled at over 26,000 locations and representing over 47,000 species. We outline how the database can help in answering a range of questions in ecology and conservation biology. To our knowledge, this is the largest and most geographically and taxonomically representative database of spatial comparisons of biodiversity that has been collated to date; it will be useful to researchers and international efforts wishing to model and understand the global status of biodiversity.

Aim: Anthropogenic land‐use change is a major driver of the current extinction crisis, but the processes through which it acts on biodiversity are complex and still poorly understood. Here, we use several biodiversity metrics to make a comprehensive assessment of the response of an endemic‐rich bird assemblage to land‐use change.Location: São Tomé Island (São Tomé and Príncipe, Africa).Methods: We sampled bird assemblages in 220 point counts, stratified across three regions and four land‐use types. Species richness was examined using accumulation curves and generalized linear mixed‐effect models. Compositional and structural changes were analysed with ordination techniques. We used correlations and model selection to identify species traits and environmental variables associated with such changes.Results: At the point level, there was a slight decrease of species richness in more intensive land uses. However, higher dissimilarities within these land uses led them to have higher overall species richness. Endemics dominated forest environments and, although most preferred less‐disturbed land uses, many persisted across all land uses. Non‐endemics were virtually absent from forests, but became very abundant in the more intensive land uses. Canopy cover was the best predictor of the shift between endemic and non‐endemic species, and allowed identifying regional differences in the local responses of bird assemblages to land‐use change.Main conclusions: To better understand biodiversity, it is crucial to use several metrics simultaneously. In São Tomé, simply using species richness, the single most used biodiversity metric, could have been misleading as it concealed major shifts in the bird assemblage structure towards an endemism impoverished avifauna. Despite scarce data on land‐use cover, we demonstrate how landscape context can be vital to understand biodiversity patterns and that highly forested surroundings might overestimate the strict value of more intensive land uses. Our results raise concerns about the long‐term persistence of endemic species restricted to islands where forested land uses are being lost.