Explore the vast range of titles available.

Mangrove species are uniquely adapted to tropical and subtropical coasts, and although relatively low in number of species, mangrove forests provide at least US $1.6 billion each year in ecosystem services and support coastal livelihoods worldwide. Globally, mangrove areas are declining rapidly as they are cleared for coastal development and aquaculture and logged for timber and fuel production. Little is known about the effects of mangrove area loss on individual mangrove species and local or regional populations. To address this gap, species-specific information on global distribution, population status, life history traits, and major threats were compiled for each of the 70 known species of mangroves. Each species' probability of extinction was assessed under the Categories and Criteria of the IUCN Red List of Threatened Species. Eleven of the 70 mangrove species (16%) are at elevated threat of extinction. Particular areas of geographical concern include the Atlantic and Pacific coasts of Central America, where as many as 40% of mangroves species present are threatened with extinction. Across the globe, mangrove species found primarily in the high intertidal and upstream estuarine zones, which often have specific freshwater requirements and patchy distributions, are the most threatened because they are often the first cleared for development of aquaculture and agriculture. The loss of mangrove species will have devastating economic and environmental consequences for coastal communities, especially in those areas with low mangrove diversity and high mangrove area or species loss. Several species at high risk of extinction may disappear well before the next decade if existing protective measures are not enforced.

Natural processes tend to vary over time and space, as well as between species. The ecosystem services these natural processes provide are therefore also highly variable. It is often assumed that ecosystem services are provided linearly (unvaryingly, at a steady rate), but natural processes are characterized by thresholds and limiting functions. In this paper, we describe the variability observed in wave attenuation provided by marshes, mangroves, seagrasses, and coral reefs and therefore also in coastal protection. We calculate the economic consequences of assuming coastal protection to be linear. We suggest that, in order to refine ecosystem-based management practices, it is essential that natural variability and cumulative effects be considered in the valuation of ecosystem services.

Opportunities to boost climate change mitigation and adaptation (CCMA) and sustainable conservation financing may lie in enhancing blue carbon sequestration, particularly in developing nations where coastal ecosystems are extensive and international carbon markets offer comparatively attractive payments for environmental stewardship. While blue carbon is receiving increased global attention, few credit-generating projects are operational, due to low credit-buyer incentives with uncertainty in creditable emissions reductions and high project costs. Little empirical guidance exists for practitioners to quantify return-on-investment (ROI) and viability of potential projects, particularly for rehabilitation where multiple implementation options exist with diverse associated costs. We map and model drivers of mangrove natural regeneration (NR) using remote sensing (high-resolution satellite imagery segmentation and time-series modeling), and subsequent carbon sequestration using field- and literature-derived data, across abandoned aquaculture ponds in the Philippines. Using project-specific cost data, we then assess ROI for a hypothetical rehabilitation-focused mangrove blue carbon project at a 9.68 ha abandoned pond over a 10-year timeframe, under varied rehabilitation scenarios [NR vs. assisted natural regeneration (ANR) with planting], potential emissions reduction accreditation methodologies, carbon prices and discount rates. NR was faster in lower-lying ponds with lower tidal exposure (greater pond dike retention). Forecasted carbon sequestration was 3.7- to 5.2-fold and areal “greenbelt” regeneration 2.5- to 3.4-fold greater in our case study under ANR than NR. Variability in modeled sequestration rates drove high uncertainty and credit deductions in NR strategies. ROI with biomass-only accreditation was low and negative under NR and ANR, respectively. ROI was greater under ANR with inclusion of biomass and autochthonous soil carbon; however, neither strategy was highly profitable at current voluntary market carbon prices. ANR was the only scenario that fulfilled coastal protection greenbelt potential, with full mangrove cover within 10 years. Our findings highlight the benefits of ANR and soils inclusion in rehabilitation-oriented blue carbon projects, to maximize carbon sequestration and greenbelt enhancement (thus enhance pricing with potential bundled credits), and minimize forecasting uncertainty and credit-buyers’ perceived risk. An ANR rehabilitation strategy in low-lying, sea-facing abandoned ponds with low biophysical intervention costs may represent large blue carbon CCMA opportunities in regions with high aquaculture abandonment.

Global production of farmed fish and shellfish has more than doubled in the past 15 years. Many people believe that such growth relieves pressure on ocean fisheries, but the opposite is true for some types of aquaculture. Farming carnivorous species requires large inputs of wild fish for feed. Some aquaculture systems also reduce wild fish supplies through habitat modification, wild seedstock collection and other ecological impacts. On balance, global aquaculture production still adds to world fish supplies; however, if the growing aquaculture industry is to sustain its contribution to world fish supplies, it must reduce wild fish inputs in feed and adopt more ecologically sound management practices.

Aquaculture, the farming of shrimp and other useful aquatic and marine plants and animals in artificially confined and tended ponds, pens, and cages, ranks as a phenomenal success story in global food production. In 1975, aquaculture contributed 8% to the overall yield of the world's fish harvest; now it provides more than one-third of the yield. Total aquaculture production in 2003 was 54.8 million metric tons valued at $67.3 billion in U.S. dollars. More than 90% of this output comes from Asia, where aquaculture has its origins and where this month's essay author has lived and worked all of her life. In her essay, Jurgenne H. Primavera, senior scientist of the Aquaculture Department of the Southeast Asian Fisheries Development Center based in Iloilo, Central Philippines, traces the recent history of aquaculture and the socioeconomic and environmental challenges that its rapid growth has wrought, especially for the mangrove ecosystems in which much of brackishwater pond aquaculture occurs. With an eye on all stakeholders, Primavera lays out how aquaculture is now falling short of the goal of sustainability and what steps might be taken to move the industry in that direction.

Competition for coastal land use and overexploitation have reduced or degraded mangrove coverage throughout much of their distribution, especially in South-east Asia. Timber production was the initial motivation for early mangrove reforestation projects. More recently, benefits from protection against erosion and extreme weather events and direct improvements in livelihoods and food security are perceived as justifications for such restoration efforts. This study examines the socioeconomic impacts of a community-led reforestation project in the Philippines through a survey of the local fishers. Revenues from mangrove fisheries, tourism and timber result in an annual benefit to the community of US$ 315 ha−1 yr−1. This figure is likely to be considerably more if the contribution of the mangrove to the coastal catch of mangrove-associated species is included. This estimate only includes direct benefits to the community from mangroves, and not intangible benefits such as coastal protection, which paradoxically is perceived by the community as one of the most important functions. More than 90% of all fishers, regardless of where they fished, thought the mangrove provided protection from storms and typhoons and acted as a nursery site and should be protected. Those fishing only in the mangrove perceived more benefits from the mangrove and were prepared to pay more to protect it than those fishing outside. This study concludes that replanting mangroves can have a significant economic impact on the lives of coastal communities. Acknowledgement of the value of replanted mangroves compared with other coastal activities and the benefits they bring to the more economically-vulnerable coastal dwellers should support better informed policy and decision-making with regard to coastal habitat restoration.

Practical mapping methods employing GPS field surveys and manual image analyses with affordable software were used to assess two mangrove sites in Aklan Province, NE Panay Island, central Philippines. The Jawili mangroves, absent from current maps, actually included 21.5 ha with 24 true mangrove species. On the other hand, the Batan Estuary mangroves, shown to be 4244 ha in available topographic maps, revealed only 406 ha of scattered patches. Actual mangrove data on specific areas worldwide is limited, especially in the Philippines where available maps show discrepancies from actual mangrove distribution. Remote sensing (RS) techniques provide promising results but require expensive setup, particularly for small areas. Therefore, financially limited users need affordable and rapid mapping alternatives. The practical techniques presented here can be immediately implemented at minimal cost and can produce useful estimates of actual mangrove area, fundamental for coastal management. Basic principles used here also have potential applications in other systems and locations. When resources are available though, additional confirmation and precise mapping are also further recommended.

From half a million hectares at the turn of the century, Philippine mangroves have declined to only 120,000 ha while fish/shrimp culture ponds have increased to 232,000 ha. Mangrove replanting programs have thus been popular, from community initiatives (1930s-1950s) to government-sponsored projects (1970s) to large-scale international development assistance programs (1980s to present). Planting costs escalated from less than US$100 to over $500/ha, with half of the latter amount allocated to administration, supervision and project management. Despite heavy funds for massive rehabilitation of mangrove forests over the last two decades, the long-term survival rates of mangroves are generally low at 10-20%. Poor survival can be mainly traced to two factors: inappropriate species and sites selection. The favored but unsuitable Rhizophora are planted in sandy substrates of exposed coastlines instead of the natural colonizers Avicennia and Sonneratia. More significantly, planting sites are generally in the lower intertidal to subtidal zones where mangroves do not thrive rather than the optimal middle to upper intertidal levels, for a simple reason. Such ideal sites have long been converted to brackishwater fishponds whereas the former are open access areas with no ownership problems. The issue of pond ownership may be complex and difficult, but such should not outweigh ecological requirements: mangroves should be planted where fishponds are, not on seagrass beds and tidal flats where they never existed. This paper reviews eight mangrove initiatives in the Philippines and evaluates the biophysical and institutional factors behind success or failure. The authors recommend specific protocols (among them pushing for a 4:1 mangrove to pond ratio recommended for a healthy ecosystem) and wider policy directions to make mangrove rehabilitation in the country more effective.

An obituary for Angel Chua Alcala who died on Feb 1, 2023 is presented. He was a pioneer of community-led marine resource management and the premier Filipino herpetologist. Angel Alcala was born on March 1, 1929 in the tiny coastal village of Caliling, within sight of pristine tropical seas in the southwestern region of Negros Island in the central Philippines. At ten, he swam on a coral reef close to his home, which imprinted on him clear memories of coral reefs in the 1930s. He often spoke of vibrant, colorful reefs, teeming with fishes and turtles. Little did he know as a boy that in his life he would do more than probably any other Filipino to preserve these coral reefs for fisheries and conservation, for future generations of Filipinos, and for humankind.