Coastal wetland loss, consequences, and challenges for restoration

Abstract

Coastal wetlands mainly include ecosystems of mangroves, coral reefs, salt marsh, and sea grass beds. As the buffer zone between land and sea, they are frequently threatened from both sides. The world coastal wetland lost more than 50% of its area in the 20th century, largely before their great value, such as wave attenuation, erosion control, biodiversity support, and carbon sequestration, was fully recognized. World wetland loss and degradation was accelerated in the last three decades, caused by both anthropogenic and natural factors, such as land reclamation, aquaculture, urbanization, harbor and navigation channel construction, decreased sediment input from the catchments, sea level rise, and erosion. Aquaculture is one of the key destinations of coastal wetland transformation. Profound consequences have been caused by coastal wetland loss, such as habitat loss for wild species, CO 2 and N 2 O emission from land reclamation and aquaculture, and flooding. Great efforts have been made to restore coastal wetlands, but challenges remain due to lack of knowledge about interactions between vegetation and morphological dynamics. Compromise among the different functionalities remains a challenge during restoration of coastal wetlands, especially when faced with highly profitable coastal land use. To solve the problem, multi-disciplinary efforts are needed from physio-chemical-biological monitoring to modelling, designing, and restoring practices with site-specific knowledge.

Microbial resistance and resilience in response to environmental changes under the higher intensity of human activities than global average level

“…Here, we are presenting a study about microbial resistance and resilience to different human activities in the second largest coastal ecosystem in the Pearl River Estuary (PRE) of China, where urbanization and agriculturalization (e.g., reclamation, and aquaculture) are recognized as the two major human disturbances driven by the rapid coastward migration of the population (Li, Bellerby, Craft, & Widney, 2018). In this region, the growth of coastal urban areas has been reported to be more than three times the national rate (McGranahan, Balk, & Anderson, 2007;Neumann, Vafeidis, Zimmermann, & Nicholls, 2015) with high population density of around 1,000-4,000 people/km 2 on average even in 2010 (Yu, Liu, & Zhang, 2018); this region is increasingly undergoing different environmental pressures related to human activities and disturbances.…”

Effects of salt marsh restoration on eukaryotic microbenthic communities in the Yangtze Estuary

“…Coastal salt marshes provide important ecosystem services. One of their essential functions is conserving high biodiversity of native species, including nekton, invertebrates, waterbirds, and cryptic microorganisms, through providing food sources and diverse habitats (Ferguson & Rakocinski 2008, X. Li et al 2018. However, salt marsh ecosystems are facing great pressures due to anthropogenic activities, such as reclamation, eutrophication, exotic species invasion, and habitat alteration, including restoration, which could fundamentally change the physical pro -perties and ecological dynamics of marshes (Gedan et al 2009, X. Li et al 2018.…”

Mapping Trajectories of Coastal Land Reclamation in Nine Deltaic Megacities using Google Earth Engine

“…Since 1985, more than 6000 km 2 of land has been reclaimed in China, principally within and around its shining coastal cities; where coastal reclamation is especially concentrated in cities located in its three highly vulnerable deltaic ecosystems [10]. Notwithstanding the associated deleterious environmental and ecological impacts [5,6,11,12], coastal land reclamation has emerged in China as a key strategy to address three issues, i.e., urban land scarcity, the promotion of a so-called 'eco-civilization', and as an adaptive measure to combat sea level rise [7,13,14].…”