The “Mangroves of the Tropical Southwestern Atlantic” (TSA) is a regional ecosystem subgroup (level 4 unit of the IUCN Global Ecosystem Typology). It includes the marine ecoregions of Eastern Brazil, Northeastern Brazil, including the Fernando de Noronha Archipelago and Rocas Atoll. The TSA mangroves had a mapped extent of 1719.7 km2 in 2020, representing 1.2% of the global mangrove area. The flora is characterized by four true mangrove species: Rhizophora mangle, Avicennia schaueriana, A. germinans and Laguncularia racemosa. They provide essential biological functions such as supplying food resources to nearby settlements, including fish, crabs, mussels, and prawns, as well as timber and coastal defence. Furthermore, these environments promote ecological interactions with adjacent coral reefs. The climate ranges from humid to semi-arid along the Brazilian coast, which influences the diversity of geological environments and forest structures in the mangrove ecosystem. Despite their ecological and socio-economic importance, mangroves are at risk from conversion to aquaculture, salt panning, coastal infrastructure development, and oil pollution. Mangroves have also been significantly impacted by two recent major disasters: the 2015 collapse of the Mariana dam, which released a vast quantity of iron mining waste, and an extensive oil spill along the Brazilian northeast coast in 2019. As of today, the TSA mangrove ecosystem area has undergone a net loss of -3.7% since 1996. If this trend continues an overall change of -6.7% is projected over the next 50 years. Furthermore, under a high sea level rise scenario (IPCC RCP8.5) ≈10.5% of the TSA mangrove area would be submerged by 2060. Moreover, 2.2% of the province’s mangrove ecosystem is undergoing degradation, with the potential to increase to 6.6% within a 50-year period, based on a vegetation index decay analysis. Overall, the Tropical Southwestern Atlantic mangrove ecosystem is assessed as Least Concern (LC).
Tag: aquaculture
Back to baselines: measuring change and sharing data
International research for development is under increasing pressure to demonstrate development outcomes that enhance people’s food security and well-being while preserving the natural resource base. The CGIAR Research Programme on Climate Change, Agriculture and Food Security (CCAFS) integrates thematic research at several levels with multiple global, regional and local partners, with the aim of identifying and testing pro-poor adaptation and mitigation practices, technologies and policies for food systems, adaptive capacity and rural livelihoods. We describe a process to design and implement baselines across 2,095 households and 108 villages spread over 15 sites in 12 countries of West and East Africa and South Asia, and to archive, document and analyse the data and make them publicly available. We critically examine the process in relation to design, institutional arrangements, and partnerships. The process was long, complex and expensive. We share important lessons learned regarding how to obtain baseline data for rural populations in agricultural systems, as a basis for prioritising research and monitoring progress towards enhanced food security and increased household welfa re, in part through uptake of sustainable changes in agricultural practices
Brackish-water aquaculture in Aceh: post tsunami rehabilitation and problems
The December 2004 tsunami brought Aceh and its coastal zone to the forefront of public interest indiscussions on environment and development. Conversion of mangrove forest to shrimp/fish ponds inthe 1980s almost certainly increased the death toll from the tsunami. The devastation wasunprecedented in recorded human history. After the emergency relief phase, when clean water, food andshelter were available and the wounded had received care, the discussion started on sustainablelivelihood options along the coast – but also on the ‘causes’ of the human damage and the role of thefish/ shrimp ponds.
Maintaining Diversity of Integrated Rice and Fish Production Confers Adaptability of Food Systems to Global Change
Rice and fish are preferred foods, critical for healthy and nutritious diets, and provide the foundations of local and national economies across Asia. Although transformations, or “revolutions,” in agriculture and aquaculture over the past half-century have primarily relied upon intensified monoculture to increase rice and fish production, agroecological approaches that support biodiversity and utilize natural processes are particularly relevant for achieving a transformation toward food systems with more inclusive, nutrition-sensitive, and ecologically sound outcomes. Rice and fish production are frequently integrated within the same physical, temporal, and social spaces, with substantial variation amongst the types of production practice and their extent. In Cambodia, rice field fisheries that strongly rely upon natural processes persist in up to 80% of rice farmland, whereas more input and infrastructure dependent rice-shrimp culture is expanding within the rice farmland of Vietnam. We demonstrate how a diverse suite of integrated production practices contribute to sustainable and nutrition-sensitive food systems policy, research, and practice. We first develop a typology of integrated production practices illustrating the nature and degree of: (a) fish stocking, (b) water management, (c) use of synthetic inputs, and (d) institutions that control access to fish. Second, we summarize recent research and innovations that have improved the performance of each type of practice. Third, we synthesize data on the prevalence, outcomes, and trajectories of these practices in four South and Southeast Asian countries that rely heavily on fish and rice for food and nutrition security. Focusing on changes since the food systems transformation brought about by the Green Revolution, we illustrate how integrated production practices continue to serve a variety of objectives to varying degrees: food and nutrition security, rural livelihood diversification and income improvement, and biodiversity conservation. Five shifts to support contemporary food system transformations [i.e., disaggregating (1) production practices and (2) objectives, (3) utilizing diverse metrics, (4) valuing emergent, place-based innovation, (5) building adaptive capacity] would accelerate progress toward Sustainable Development Goal 2, specifically through ensuring ecosystem maintenance, sustainable food production, and resilient agricultural practices with the capacity to adapt to global change.
Mangrove blue carbon stocks and dynamics are controlled by hydrogeomorphic settings and land-use change
Globally, carbon-rich mangrove forests are deforested and degraded due to land-use and land-cover change (LULCC). The impact of mangrove deforestation on carbon emissions has been reported on a global scale; however, uncertainty remains at subnational scales due to geographical variability and field data limitations. We present an assessment of blue carbon storage at five mangrove sites across West Papua Province, Indonesia, a region that supports 10% of the world’s mangrove area. The sites are representative of contrasting hydrogeomorphic settings and also capture change over a 25 year of LULCC chronosequence. Field-based assessments were conducted across 255 plots covering undisturbed and LULCC-affected mangroves (0-, 5-, 10-, 15- and 25-year-old post-harvest or regenerating forests as well as 15-year-old aquaculture ponds). Undisturbed mangroves stored total ecosystem carbon stocks of 182-2730 (mean ± SD: 1,087 ± 584) Mg C/ha, with the large variation driven by hydrogeomorphic settings. The highest carbon stocks were found in estuarine interior mangroves, followed by open coast interior, open coast fringe and estuarine interior forests. Forest harvesting did not significantly affect soil carbon stocks, despite an elevated dead wood density relative to undisturbed forests, but it did remove nearly all live biomass. Aquaculture conversion removed 60% of soil carbon stock and 85% of live biomass carbon stock, relative to reference sites. By contrast, mangroves left to regenerate for more than 25 years reached the same level of biomass carbon compared to undisturbed forests, with annual biomass accumulation rates of 3.6 ± 1.1 Mg C/ha/year. This study shows that hydrogeomorphic setting controls natural dynamics of mangrove blue carbon stocks, while long-term land-use changes affect carbon loss and gain to a substantial degree. Therefore, current land-based climate policies must incorporate landscape and land-use characteristics, and their related carbon management consequences, for more effective emissions reduction targets and restoration outcomes.
Carbon stocks and effluxes in mangroves converted into aquaculture: a case study from Banten province, Indonesia
Aquaculture is one of the main drivers of mangrove loss across Southeast Asian countries. The conversion of mangroves to aquaculture generates substantial loss of carbon stocks and reduces carbon storage capacity. Here, we present total ecosystem carbon stocks (TECS), carbon dioxide (CO2) and methane (CH4) effluxes obtained from mangrove forests (fringe and interior mangroves), silvofishery aquaculture ponds (dense and sparse mangroves), and non-silvofishery aquaculture ponds in Sawah Luhur, Banten, Indonesia. We found no significant difference in TECS across five land uses, ranging from 261 ± 14 Mg C ha-1 in non-silvofishery ponds to 574 ± 119 Mg C ha-1 in fringe mangroves. Most of these stocks were found in the soil carbon pool (87%) in fringe and interior mangroves. However, the conversion of mangroves to aquaculture ponds resulted in soil carbon loss from -6% to 60%. The highest soil CO2 effluxes during dry and wet seasons were observed in interior mangroves (151 ± 12 mg CO2 m-2 h-1). The highest soil CH4 effluxes were found in fringe mangroves with 0.13 ± 0.04 mg CH4 m-2 h-1. The highest aquatic CO2 and CH4 effluxes were found in dense silvofishery ponds, at 118 ± 7 mg CO2 m-2 h-1 and 0.38 ± 0.04 mg CH4 m-2 h-1, respectively. Our findings suggest that land use that includes mangroves (i.e., mangrove forest and/or silvofishery ponds) tends to have higher carbon stocks, soil, and aquatic CO2 and CH4 effluxes, compared to aquaculture ponds without mangroves. It is therefore crucial to maintain mangroves for natural carbon capture and storage through carbon stock enhancement.