Structure, Functioning and Conservation of Coastal Vegetated Wetlands

Coastal wetlands— mangroves, saltmarshes and seagrass beds— occupy a narrow fringe along the shores of all continents. Their global cover is small, yet they are profoundly important to human livelihoods and the regulation of physical, chemical and biological processes, and thereby to coastal resilience. As examples, they have a central role in nature-based flood and erosion protection, much to the interest of mitigative coastal zone planning. Up to 10% of all oceanic carbon pass through coastal wetlands and their ‘blue carbon’ stores exceed those of equivalent terrestrial habitats. They are also important filterers of coastal pollutants and they provide habitat to a wide array of species. Land reclamation, deforestation, eutrophication and other anthropogenic perturbations threaten the ecosystem processes and services of coastal wetlands: there has been a 25-50% reduction in their area-cover over the past five decades. Climate change is further affecting functioning and distribution, for instance causing poleward migration of mangroves.

The mechanistic processes by which natural benefits, such as coastal protection and carbon storing, come about is not well resolved, nor is it clear how they will respond to area losses, climatic change and sea-level rise. Coastal wetlands are now in vogue and are commonly used as model systems for addressing globally important research frontiers. A 2008 special issue on mangroves generated many highly cited papers. Ten years on, we argue the time is ripe for a special issue to take status on research into coastal wetlands.

The Research Topic will place particular focus on coastal wetland distribution, structure, functioning, management and restoration. It will be structured around the following six themes:
(i) the biogeographic variation in coastal wetlands structure and functioning, with special emphasis on
(ii) biogeochemical fluxes and balances of carbon, nutrients and chemicals, and on
(iii) coastal and seascape ecology, interspecific relationships and food webs;
(iv) patterns and processes of change in coastal wetlands cover and distribution and
(v) of degradation and resilience to environmental and anthropogenic disturbances (including climate change); and
(vi) the monitoring, management and restoration of coastal wetlands.

There is a need for resolving the causes for global variation in research on these six themes. Numerous methods and metrics have been used to describe coastal wetlands and to assess their ecological status. Yet the understanding of their functioning and the use of resulting environmental indices is often inconsistent or not practiced, and/or relies on the knowledge of reference conditions and long-term assessment programs, which may or may not exist. A good overview of these processes is needed.

Conservation and restoration programs alongside environmental assessments have yielded both encouraging and disappointing impacts on ecosystem functioning and human welfare. Because restoration successes depend primarily on the habitat type, site selection and the techniques applied, it is essential to have a thorough understanding of the causes of variation in the functioning of coastal wetlands. This Research Topic of Frontiers in Ecology and Evolution will help resolve some of these issues by publishing highly contemporary, novel research findings alongside state of the art reviews of research into coastal wetlands functioning.