Mangroves are essential coastal ecosystems distributed across tropical and subtropical regions, typically found at the confluence of river systems and the sea. Although air temperature has long been recognised as a key determinant of mangrove distribution, upwelling systems that transport cold, nutrient-rich waters from the deep ocean to the surface can also impede mangrove propagule dispersion. However, global studies that examine the influence of upwelling on mangrove distribution remain scarce. In this study, our objective was to investigate the relationship between upwelling systems and global mangrove distribution, with an emphasis on range limits and area extent. We adopted a novel multi-scale approach by analysing mangrove areas at several minimum size thresholds (≥5 ha, ≥50 ha, ≥100 ha, ≥200 ha, and ≥ 300 ha) to evaluate the scale dependence of upwelling effects. Our regression models revealed a clear trend: the coefficient of determination (R2) increased from 0.20 for patches ≥5 ha to 0.37 for ≥50 ha, 0.43 for ≥100 ha, 0.49 for ≥200 ha, and reached 0.53 for patches ≥300 ha. Furthermore, low-upwelling regions harbour 47.7 % of the total mangrove area (66,763 km2), whereas high-upwelling regions account for only 0.5 % (2642 km2). We also found that the highest upwelling intensities occur exclusively in the Atlantic East Pacific mangrove region, a key environmental contrast to the Indo-West Pacific. In conclusion, our study demonstrates that upwelling systems are one factor shaping global mangrove distribution in a strongly scale-dependent manner, with larger, contiguous patches exhibiting a markedly stronger response. These insights emphasise the need to incorporate upwelling intensity and spatial scale into global mangrove conservation and management strategies. This integration is essential to address the complex interplay of environmental factors under shifting oceanographic and climatic conditions.
Tag: mangroves
Vietnam blue carbon opportunity assessment
Marine and coastal ecosystems, including mangroves and seagrass meadows, are global hotspots for “blue carbon” storage in vegetation and soils, but face mounting pressure from human activities and climate change. Mechanisms that mobilize foreign direct investment to reduce anthropogenic greenhouse gas emissions and enhance sustainable development, such as voluntary carbon projects, offer financing that can complement government efforts. We assessed blue carbon opportunities in Vietnam focusing on mangroves and seagrass in the Mekong Delta coastal provinces (Kien Giang, Ca Mau, Bac Lieu, Soc Trang, Tra Vinh, Ben Tre and Tien Giang). Object-based image analysis was used to quantify changes in the extent of mangroves from 2016 – 2024. To assess fluctuations in seagrass meadow areas we projected historical changes in seagrass coverage reported in the literature. Emissions of CO2 resulting from changes in mangrove forest and seagrass meadow coverages were estimated using literature-based emission factors. Overall, mangrove coverage in the Mekong Delta coastal provinces declined between 2016 and 2024, despite areas of mangrove expansion. CO2 removals from mangrove area increase did not offset CO2 emissions from mangrove loss during 2016–2024. Our analysis revealed substantial losses in some areas, highlighting the complex dynamics of mangrove conservation. The total net impact of mangrove loss and reforestation in the seven provinces during this period was 14.5 million Mg CO2, with Ca Mau province contributing 77% of emissions. The magnitude of potential CO2 emissions from seagrass loss was smaller, at 31.4 thousand Mg CO2, concentrated in the area of Phu Quoc Island in Kien Giang province. Our results emphasize the need to avoid continued conversion of mangroves, despite gains in mangrove forest areas.
Species-Poor Mangrove Forests also Provide Rich Ecosystem Goods and Services
Mangrove forests provide a wide range of services to coastal communities worldwide. These services include carbon sequestration and coastal protection, both of which are critical in the context of climate change. However, these wetlands are still experiencing destructive anthropogenic impacts in many areas. Senegal and Colombia, two countries in the Atlantic-East Pacific biogeographic region, both have abundant mangrove cover and share several mangrove species. This study assessed the use of mangrove resources (fuelwood, timber, and other non-timber forest products) by local communities in both countries. A total of 210 semi-structured ethnobotanical questionnaire-based interviews were conducted in Sokone and neighboring villages bordering the Sine-Saloum Delta in Senegal (110) and in the Cispata lagoon system in Colombia (100). The results for Senegal indicate that individuals residing near the Sine-Saloum Delta in neighboring villages rely more on mangroves compared to those living in Sokone. In Colombia, reliance on mangroves was associated with occupational activities. Despite lower species diversity compared to the Indo-West Pacific biogeographic region, mangroves provide various services in both areas, underscoring their significance to local communities and their livelihoods. Finally, the Indigenous and local knowledge emphasizes the need for alternatives to mangrove resources and the promotion of sustainable harvesting practices to ensure the conservation of mangroves and the continued provision of essential services.
Mangroves of the Tropical Southwestern Atlantic
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).
Habitat distribution of Adansonia digitata inferred from ensemble modelling with BiodiversityR
Vegetation resistance and regeneration potential of Rhizophora, Sonneratia and Avicennia in the Typhoon Haiyan-affected mangroves in the Philippines: Implications on rehabilitation practices
Typhoons cause damage to mangrove ecosystems, hampering their delivery of ecosystem goods and services, including coastal protection. We examined the vegetation resistance (VR) and seedling regeneration potential (SRP) of three mangrove genera: Rhizophora, Sonneratia and Avicennia at the seafront areas. We assessed genus-specific resistance to and recovery from the impacts of Typhoon Haiyan, by far the strongest storm to make landfall in recorded history. VR was estimated using density, tree height and diameter at breast height (DBH). SRP was measured as the post-disturbance seedling growth rate within a given plot.Thirty-six 3m-radii plots were established in the typhoon-affected mangrove areas of Ormoc City and Tacloban City in Leyte; and Quinapondan and General MacArthur in Eastern Samar. Results showed that Avicennia and Sonneratia species yielded the higher average VR values, as compared to Rhizophora,which had the lowest VR across all sites. The different genera could also be arranged from highest to lowest SRP: Avicennia (67.27 ± 2.62 cmyr-1)>Rhizophora (32.46 ± 4.64 cmyr-1). Overall, our findings on the higher relative VR and SRP values of Sonneratia and Avicennia calls for a shift to these species in mangrove planting at the seafront areas, which currently favor Rhizophora. – See more at: https://www.cddjournal.org/article/view/vol01-iss01-001#sthash.22CAKqC7.dpuf
Profile of Action Arena: Sungsang Mangrove Restoration and Ecotourism (SMART)
CIFOR-ICRAF and partners, Sriwijaya University and the South Sumatra Watershed Forum (Forum DAS Sumsel) are conducting participatory action research (PAR) to develop locally accepted and sustainable business models in the Sungsang area of Banyuasin District, South Sumatra Province. This PAR will eventually allow communities to generate sustainable incomes from mangrove restoration; strengthen local policies for mangrove restoration; and contribute to national and global mangrove restoration agendas. The project, which runs from 2021 to 2025 in collaboration with the Banyuasin District Government, is supported by Temasek Foundation (TF), Singapore. As per June 2024, there are six action arenas in three villages and a community-based mangrove nursery.
Climate Change Vulnerability Assessment in Mangrove-Dependent Communities of Manoka Island, Littoral Region of Cameroon
This study was conducted on Manoka Island (Littoral Region of Cameroon) with the aim of analyzing climate change vulnerability and local adaptation strategies based on the local community’s perceptions and biophysical evidence. We used household surveys, focus group discussions, field observation, GIS, and remote sensing to collect data on variables of exposure, sensitivity, and adaptive capacity. Historical changes in rainfall and temperature, mangrove cover, and the occurrence of extreme climatic events were used as indicators of exposure. Property losses and income structure were used as indicators of sensitivity, while human, natural, social, financial, and physical assets represented adaptive capacity. 89 households were interviewed in the nine settlements of the island. Results show that Manoka Island is experiencing irregular rainfall patterns (with average annual values deviating from the mean by −1.9 to +1.8 mm) and increasing temperature (with annual values deviating from the mean by −1.2 to +3.12). The dynamics of the coastline between 1975 and 2017 using EPR show average setbacks of more than ±3 m/year, with erosion levels varying depending on the period and location. The number of households perceiving extreme climatic events like seasonal variability, flood, and rain storm was higher. From respondents’ perception, housing and health are the sectors most affected by climate change. The reported high dependence of households on fishing for income, their overall low livelihood diversification, and their poor access to climate information reported by 65% of respondents portray their poor adaptive capacity. Local response initiatives are ineffective and include among others constructing buildings on stilts and using car wheels to counter the advancement of seawater inland. The study concludes that households on Manoka Island are vulnerable to the impacts of climate change. Income diversification, mangrove reforestation, the development of sustainable supply chains for wood fuel, and sustainable fish smoking devices are the main pathways for adaptation planning in this area.
Prospects of Adaptability and Establishment of Mangroves to Achieve Carbon Capture Expansion in Korean Coastal Areas
The research team was first tasked with finding a solution to the need for more creative ways to contribute to natural carbon capture and storage solutions to meet South Korea’s national climate-change objective of reaching net zero by 2050. It was through this, and the unique properties of Korea’s southern islands, that true mangroves and mangrove associates (semi-mangroves) were suggested as possible candidates that could promise high carbon absorption rates and adaptability to continue to provide ecosystem services under climate change. Some pre-existing native habitats of semi-mangrove species (e.g. Hibiscus hamabo, Paliurus ramosissimus) on Jeju Island had already demonstrated comparatively higher carbon absorption abilities than other broadleaf species as measured by photosynthesis rates and soil carbon storage performance. This study’s sole objective is to evaluate candidate mangrove species for their suitability for responsibly planned propagation in South Korea. This includes also evaluating their carbon uptake capabilities in order to forecast projections on the carbon storage and absorption performance of selected species. This study is an opportunity to contribute knowledge towards global emission reduction and climate-change mitigation objectives, especially, given the high concentration of highly vulnerable or at-risk populations in the Asia-Pacific.
Understanding the states and dynamics of mangrove forests in land cover transitions of The Gambia using a Fourier transformation of Landsat and MODIS time series in Google Earth Engine
Mangroves are resilient forests of transitional zones between land, ocean and freshwater for they are tolerant to salinity. In The Gambia, mangrove forests are found along the coast of Atlantic Ocean and River Gambia where they support the livelihoods of millions through multiple ecosystems services. Despite their importance in The Gambia, consistent country-wide information on their coverage, dynamics and change hotspots are lacking. Thus far, it remains unclear whether the coverage of mangroves has decreased or increased over the last few decades. Often, the existing estimates vary strongly across sources and the methodologies in the available literature are not always reproducible. This study attempts to fill these gaps by providing up-to-date spatial information on mangrove forests in The Gambia.