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Coastal wetlands trap plastics from terrestrial and marine sources, but the stocks of plastics and their impacts on coastal wetlands are poorly known. We evaluated the stocks, fate, and biological and biogeochemical effects of plastics in coastal wetlands with plastic abundance data from 112 studies. The representative abundance of plastics that occurs in coastal wetland sediments and is ingested by marine animals reaches 156.7 and 98.3 items kg–1, respectively, 200 times higher than that (0.43 items kg–1) in the water column. Plastics are more abundant in mangrove forests and tidal marshes than in tidal flats and seagrass meadows. The variation in plastic abundance is related to climatic and geographic zones, seasons, and population density or plastic waste management. The abundance of plastics ingested by pelagic and demersal fish increases with fish length and dry weight. The dominant characteristics of plastics ingested by marine animals are correlated with those found in coastal wetland sediments. Microplastics exert negative effects on biota abundance and mangrove survival but positive effects on sediment nutrients, leaf drop, and carbon emission. We highlight that plastic pollution is widespread in coastal wetlands and actions are urged to include microplastics in ecosystem health and degradation assessment.

Protecting existing mangrove forests is a priority for global conservation because of the wide range of services that these coastal forests provide to humankind. Despite the recent reduction in global rates of mangrove loss, high historical loss rates mean that there are at least 800,000 ha globally that are potentially suitable for mangrove re-establishment. Recently deposited mud banks or intertidal, previously terrestrial, land might provide additional habitat for expanding mangrove areas locally. There is a long history of mangrove rehabilitation. However, despite numerous good examples of, and growing expertise in, natural or assisted (re-)establishment activities, most mangrove planting efforts, for instance, either fail entirely or meet with only limited success. Exposed to waves and currents and subject to tidal inundation, mangroves differ from terrestrial forests, and approaches to, or tools for, terrestrial forest restoration cannot easily be transferred to mangrove forests. Successful mangrove (re-)establishment usually requires a robust understanding of the abiotic and biotic conditions of the chosen site, the ecological requirements of the mangrove species used or facilitated, the reasons for previous mangrove loss or degradation, as well as the barriers–both societal and ecological–that have prevented natural recovery to date. Because most mangrove forests are socio-ecological systems, with which local human populations are intimately engaged, (re-)establishment will normally require the support of, and engagement with, local communities and other local stakeholders. Here, we summarize where, when and why (re-)establishment of mangroves is needed and how to assess this need. We discuss a range of potential aims and goals of mangrove (re-)establishment along with potential pitfalls along the way from conceiving the initial idea to its realization. We compare different technical and conceptual approaches to mangrove (re-)establishment, their challenges, SCOPUS: re.j, iiTSE, info:eu-repo/semantics/published

The status and potential degradation of an ecosystem is often difficult to identify, quantify, and characterize. Multiple, concurrent drivers of degradation may interact and have cumulative and confounding effects, making mitigation and rehabilitation actions challenging to achieve. Ecosystem status assessments generally emphasize areal change (gains/losses) as a primary indicator; however, this over-simplifies complex ecosystem dynamics and ignores metrics that would better assess ecosystem quality. Consideration of multiple indicators is necessary to characterize and/or anticipate ecosystem degradation and appropriately identify factors causing changes. We utilize mangrove forests as a model system due to their distribution across a wide range of geographic settings, their position in the inherently dynamic coastal zone, and the multiple natural and anthropogenic pressures they face. We present a conceptual framework to: i) examine drivers of ecosystem degradation and characterize system status, and ii) delineate the roles of biogeographic and geomorphic variability, site history and typology, and references. A complementary workflow is proposed for implementing the conceptual framework. We demonstrate the universal applicability of our conceptual framework through a series of case studies that represent locations with differing drivers of degradation and biogeographic and geomorphic conditions. Our conceptual framework facilitates scientists, conservation practitioners, and other stakeholders in considering multiple aspects of ecosystems to better assess system status and holistically evaluate degradation. This is achieved by critically evaluating suitable comparisons and relevant elements in assessing a site to understand potential actions or the outcome of previously implemented management strategies., SCOPUS: sh.j, iiTSE, info:eu-repo/semantics/published