The global decline in estuarine and coastal ecosystems (ECEs) is affecting a number of critical benefits, or ecosystem services. We review the main ecological services across a variety of ECEs, including marshes, mangroves, nearshore coral reefs, seagrass beds, and sand beaches and dunes. Where possible, we indicate estimates of the key economic values arising from these services, and discuss how the natural variability of ECEs impacts their benefits, the synergistic relationships of ECEs across seascapes, and management implications. Although reliable valuation estimates are beginning to emerge for the key services of some ECEs, such as coral reefs, salt marshes, and mangroves, many of the important benefits of seagrass beds and sand dunes and beaches have not been assessed properly. Even for coral reefs, marshes, and mangroves, important ecological services have yet to be valued reliably, such as cross-ecosystem nutrient transfer (coral reefs), erosion control (marshes), and pollution control (mangroves). An important issue for valuing certain ECE services, such as coastal protection and habitat-fishery linkages, is that the ecological functions underlying these services vary spatially and temporally. Allowing for the connectivity between ECE habitats also may have important implications for assessing the ecological functions underlying key ecosystems services, such coastal protection, control of erosion, and habitat-fishery linkages. Finally, we conclude by suggesting an action plan for protecting and/or enhancing the immediate and longer-term values of ECE services. Because the connectivity of ECEs across land-sea gradients also influences the provision of certain ecosystem services, management of the entire seascape will be necessary to preserve such synergistic effects. Other key elements of an action plan include further ecological and economic collaborative research on valuing ECE services, improving institutional and legal frameworks for management, controlling and regulating destructive economic activities, and developing ecological restoration options.

https://esajournals.onlinelibrary.wiley.com/doi/pdf/10.1890/10-1510.1

The value of estuarine and coastal ecosystem services

Marine ecosystems are centrally important to the biology of the planet, yet a comprehensive understanding of how anthropogenic climate change is affecting them has been poorly developed. Recent studies indicate that rapidly rising greenhouse gas concentrations are driving ocean systems toward conditions not seen for millions of years, with an associated risk of fundamental and irreversible ecological transformation. The impacts of anthropogenic climate change so far include decreased ocean productivity, altered food web dynamics, reduced abundance of habitat-forming species, shifting species distributions, and a greater incidence of disease. Although there is considerable uncertainty about the spatial and temporal details, climate change is clearly and fundamentally altering ocean ecosystems. Further change will continue to create enormous challenges and costs for societies worldwide, particularly those in developing countries.

http://science.sciencemag.org/content/sci/328/5985/1523.full.pdf

The impact of climate change on the world's marine ecosystems.

Food’s environmental impacts are created by millions of diverse producers. To identify solutions that are effective under this heterogeneity, we consolidated data covering five environmental indicators; 38,700 farms; and 1600 processors, packaging types, and retailers. Impact can vary 50-fold among producers of the same product, creating substantial mitigation opportunities. However, mitigation is complicated by trade-offs, multiple ways for producers to achieve low impacts, and interactions throughout the supply chain. Producers have limits on how far they can reduce impacts. Most strikingly, impacts of the lowest-impact animal products typically exceed those of vegetable substitutes, providing new evidence for the importance of dietary change. Cumulatively, our findings support an approach where producers monitor their own impacts, flexibly meet environmental targets by choosing from multiple practices, and communicate their impacts to consumers.

/pdf/reducing-food-s-environmental-impacts-through-producers-and-2xmi5ihk3n.pdf

Reducing food’s environmental impacts through producers and consumers

Recent research has highlighted the valuable role that coastal and marine ecosystems play in sequestering carbon dioxide (CO(2)). The carbon (C) sequestered in vegetated coastal ecosystems, specifically mangrove forests, seagrass beds, and salt marshes, has been termed blue carbon. Although their global area is one to two orders of magnitude smaller than that of terrestrial forests, the contribution of vegetated coastal habitats per unit area to long-term C sequestration is much greater, in part because of their efficiency in trapping suspended matter and associated organic C during tidal inundation. Despite the value of mangrove forests, seagrass beds, and salt marshes in sequestering C, and the other goods and services they provide, these systems are being lost at critical rates and action is urgently needed to prevent further degradation and loss. Recognition of the C sequestration value of vegetated coastal ecosystems provides a strong argument for their protection and restoration; however, it is necessary to improve scientific understanding of the underlying mechanisms that control C sequestration in these ecosystems. Here, we identify key areas of uncertainty and specific actions needed to address them.

https://esajournals.onlinelibrary.wiley.com/doi/epdf/10.1890/110004

A blueprint for blue carbon: toward an improved understanding of the role of vegetated coastal habitats in sequestering CO2

Aim Our scientific understanding of the extent and distribution of mangrove forests of the world is inadequate. The available global mangrove databases, compiled using disparate geospatial data sources and national statistics, need to be improved.Here,we mapped the status and distributions of global mangroves using recently available Global Land Survey (GLS) data and the Landsat archive. Methods We interpreted approximately 1000 Landsat scenes using hybrid supervised and unsupervised digital image classification techniques. Each image was normalized for variation in solar angle and earth‐sun distance by converting the digital number values to the top-of-the-atmosphere reflectance. Ground truth data and existing maps and databases were used to select training samples and also for iterative labelling. Results were validated using existing GIS data and the published literature to map ‘true mangroves’. Results The total area of mangroves in the year 2000 was 137,760 km 2 in 118 countries and territories in the tropical and subtropical regions of the world. Approximately 75% of world’s mangroves are found in just 15 countries, and only 6.9% are protected under the existing protected areas network (IUCN I-IV). Our study confirms earlier findings that the biogeographic distribution of mangroves is generallyconfinedtothetropicalandsubtropicalregionsandthelargestpercentage of mangroves is found between 5° N and 5° S latitude. Main conclusions We report that the remaining area of mangrove forest in the world is less than previously thought. Our estimate is 12.3% smaller than the most recent estimate by the Food and Agriculture Organization (FAO) of the United Nations.We present the most comprehensive, globally consistent and highest resolution (30 m) global mangrove database ever created.We developed and used better mapping techniques and data sources and mapped mangroves with better spatial and thematic details than previous studies.

http://faculty.jsd.claremont.edu/dmcfarlane/bio176mcfarlane/pdf%20papers/world%20mangrove%20distribution.pdf

Status and distribution of mangrove forests of the world using earth observation satellite data

Mangrove systems in Australia: structure, function and status. The state of the marine environment report for Australia. Technical annex 1.

Quantifying and predicting the impact of prawn farm effluent on the assimilative capacity of coastal waterways. Final report to FRDC project 97/212 and Aquaculture CRC project E1

Mangrove and nearshore connections - a status report from the Australian perspective

The science of developing an adequate database for carbon capture and storage in coastal ecosystems has progressed as has the application of this data for blue carbon projects, although not without problems. These problems have not stopped the push to incorporate blue carbon into what is now called the ‘blue economy’. Another one of the problems associated with blue carbon science and management is having a proper understanding of the actual cost of an ecosystem service, such as carbon storage; these functions can be costed in terms of their ability to assist human well-being. Stakeholder engagement is required as blue carbon projects need to be commercially attractive propositions. Insurance markets may be a way to finance or insure carbon products as carbon stores are well-recognised as a market-based commodity. The development and implementation of blue carbon projects requires a policy framework that can deal with the management, conservation and financial issues arising from such a project. A network of demonstration projects is needed to show the viability of blue carbon and to work out in a practical way the problems and pitfalls of running a project. Blue carbon as a vehicle for conservation, sustainable use and restoration also needs to be fully integrated into existing national and regional policy frameworks as a mechanism for climate change mitigation. Most projects have suffered from poor management protocols, such as not having proper success or failure criteria and have suffered from poor or uncertain methodology. Of prime importance is assessing the existing hydrology of natural habitats and then applying this information to the habitat to be restored. Financing remains a key concern for blue carbon projects, but there are many funding agencies available as finance mechanisms, including the voluntary carbon market.

The Blue Economy: Mitigation and Adaptation

Mangrove ecosystems are well-adapted to living in a dynamic and harsh environment and have survived catastrophic climate events since their first appearance 66 Mya along Tethys Sea shores. There have been past episodes of localized extinction due mostly to abrupt, rapid rises in sea-level. Living at the edge between land and sea, mangrove ecosystems are inclined to be resilient to environmental disturbance, such as highly variable changes in salinity, solar insolation, temperature, tidal inundation, freshwater inputs, and sea-level. Based on current knowledge of mangrove responses to environmental change, mangroves in subsiding river deltas, on low Pacific and Caribbean islands, and in the arid tropics are likely to decline in area, biodiversity, forest structure, and function into the Anthropocene. Mangrove forests will continue to expand latitudinally along the Gulf of Mexico, the east coast of Florida, the coasts of South Africa, eastern Australia, northern New Zealand, south eastern Brazil, and China. Regions that experience tropical storms or other extreme events, as in northern Australia, the Gulf of Mexico, the east India coast, Florida, the Philippines, south China coast, and the northern Caribbean, mangroves will likely suffer increased damage, destruction, and loss. The east coast of Sumatra, north coast of Java, Sulawesi, and southern Vietnam are likely to lose mangroves because of their low tidal range. Mangroves in other parts of Southeast Asia may response positively to increased rainfall and warmer temperatures, as on the west coast of Peninsular Malaysia and the southwest coast of Thailand. Mangroves will likely respond positively or exhibit no significant change along the tropical west and north coasts of South America and the Caribbean and Pacific coasts of Central America. Globally, mangroves are likely to survive, perhaps in altered states, into the next century.

Daniel M. Alongi

Papers

Mangrove systems in Australia: structure, function and status. The state of the marine environment report for Australia. Technical annex 1.

Quantifying and predicting the impact of prawn farm effluent on the assimilative capacity of coastal waterways. Final report to FRDC project 97/212 and Aquaculture CRC project E1

Mangrove and nearshore connections - a status report from the Australian perspective

The Blue Economy: Mitigation and Adaptation

Responses of Mangrove Ecosystems to Climate Change in the Anthropocene