MAP News Issue #590 – JAN 27, 2024

SENEGAL – Heavy metal pollution and traditional shellfish harvesting methods have unintended effects on coastal ecosystems in Senegal, a study suggests. The study led by a doctoral researcher at Åbo Akademi University in Finland showed for the first time, the impact of humans and environmental variables on Senegalese mangroves, underlining the importance of local conservation and management. Samples of sediments were collected at several sites.Credit: François Le Loc’h. The study was part of the project, Femmes et Coquillages, (Women and Shellfish), seeking to understand traditional knowledge and practices in order to contribute to sustainably harvesting shellfish resources. The team investigated the main mangrove areas in Senegal: the Sine Saloum and the Petite Cote, to evaluate the influence of environment and human activities (i.e. shellfish harvesting and heavy metal pollution) on key coastal animals. Based on collected data of invertebrates living in the sediments of the seabed from 2007 to 2008, the researchers established a conditions report for the mangrove areas to understand the factors influencing aquatic animals that live in the substrate of a body of water and which are especially common in soft sediments, known as infaunal. The results are important because “there have not been any published data on these infaunal communities since 1985. So our study serves as an important reference point for future research,” says Maïté Jacquot, the lead author.

CHINA – In recent years, the Xiatanwei Mangrove Coastal Wetland Ecological Park in Xiamen, East China’s Fujian province, has been transformed into a verdant barrier against typhoons and storm surges, owing to a series of mangrove restoration initiatives. It has also become a popular leisure and recreational spot, drawing the attention of the United Nations Secretary-General’s Special Envoy for the Ocean Peter Thomson, who has visited twice and lauded it as a model for mangrove restoration in addresses to global audiences.Xiamen is rich in aquatic resources and there are almost 2,000 known marine species, of which 157 are common fish with economic value, 89 are mollusks, 127 are crustaceans and 139 are algae. Both the amphioxus and the Chinese White Dolphin are known as first-class national protected animals in China, and the horseshoe crab is the key protected rare animal in Fujian. It has been found that there are 14 hot springs spots or thermal abnormal points, and the water temperature is usually from 50 degrees Celsius to 60 degrees Celsius, with a maximum of 90 degrees Celsius. 

SOLOMON ISLANDS – Rehabilitating and restoring Mangrove forests is a major task for communities in Langalanga Lagoon, Malaita Province. As a population known for living on artificial islands and dependent on marine resources, the community has gradually witnessed the loss of mangroves over the past decades. A locally led non-governmental organization (NGO), Batairalo Conservation and Natural Solutions Trust, is dedicated to working with tribal landowners to sustain mangrove ecosystems. Co-founder of the organization, Stephen Suti Agalo said around 50 percent of mangroves located around his childhood home are now gone. “Due to population explosion, more people are using mangroves for firewood, building materials for ships and houses, and these are also sold on the market in Honiara,” he explained. Growing demands for commercial supply of materials to Honiara, coupled with the needs of rural-based communities has placed huge pressure on available natural forests, and hampered the natural regrowth of mangroves. Meanwhile, Walebarasialia Tobata, also a co-founder of the NGO, said locals living on the lagoon’s outer islands have attempted to replant mangroves. 

FIJI – The Ministry of Women, Children and Social Protection is collaborating with other government agencies under the International Tropical Timber Organization.This is to launch a project focused on the community-based restoration of cyclone-affected vulnerable mangrove forests.The project, funded by the Japanese Government, will be implemented in six coastal communities in the Rewa Delta. Women’s groups in these communities will play a lead role in activities such as cultivating quality seedlings of indigenous mangroves, establishing energy forests, and providing fuel-saving cook stoves to reduce dependence on mangrove resources.The International Tropical Timber Organization (ITTO) is an intergovernmental organization promoting the sustainable management and conservation of tropical forests and the expansion and diversification of international trade in tropical timber from sustainably managed and legally harvested forests.It has funded and assisted in the implementation of more than 1200 projects and other activities addressing the many aspects of SFM, such as forest restoration; wood-use efficiency; the competitiveness of wood products; market intelligence and transparency in the tropical timber trade and tropical timber supply chains; forest law enforcement and governance; illegal logging; biodiversity conservation; climate-change mitigation and adaptation.

GLOBAL – Mangrove forests are a highly productive ecosystem with important potential to offset anthropogenic greenhouse gas emissions. Mangroves are expected to respond differently to climate change compared to terrestrial forests owing to their location in the tidal environment and unique ecophysiological characteristics, but the magnitude of difference remains uncertain at the global scale. Here we use satellite observations to examine mean trends and interannual variability in the productivity of global mangrove forests and nearby terrestrial evergreen broadleaf forests from 2001 to 2020. Although both types of ecosystem experienced significant recent increases in productivity, mangroves exhibited a stronger increasing trend and greater interannual variability in productivity than evergreen broadleaf forests on three-quarters of their co-occurring coasts. The difference in productivity trends is attributed to the stronger CO2 fertilization effect on mangrove photosynthesis, while the discrepancy in interannual variability is attributed to the higher sensitivities to variations in precipitation and sea level. Our results indicate that mangroves will have a faster increase in productivity than terrestrial forests in a CO2-rich future but may suffer more from deficits in water availability, highlighting a key difference between terrestrial and tidal ecosystems in their responses to climate change.

GLOBAL – Human-induced land subsidence causes many coastal areas to sink centimetres per year, exacerbating relative sea level rise (RSLR). While cities combat this problem through investment in coastal infrastructure, rural areas are highly dependent on the persistence of protective coastal ecosystems, such as mangroves and marshes. To shed light on the future of low-lying rural areas in the face of RSLR, we here studied a 20-km-long rural coastline neighbouring a sinking city in Indonesia, reportedly sinking with 8–20 cm per year. By measuring water levels in mangroves and quantifying floor raisings of village houses, we show that, while villages experienced rapidly rising water levels, their protective mangroves experience less rapid changes in RSLR. Individual trees were able to cope with RSLR rates of 4.3 (95% confidence interval 2.3–6.3) cm per year through various root adaptations when sediment was available locally. However, lateral retreat of the forest proved inevitable, with RSLR rates up to four times higher than foreshore accretion, forcing people from coastal communities to migrate as the shoreline retreated. Whereas local RSLR may be effectively reduced by better management of groundwater resources, the effects of RSLR described here predict a gloomy prospect for rural communities that are facing globally induced sea level rise beyond the control of local or regional government.

MAP is proud to release a report of our annual accomplishments and financial health for the past year. Check out a global map of the places we’re working, and highlights from all of our programs. Thank you to our many supporters who made this work possible, and to all of our friends and partners working to protect mangrove forests, worldwide.

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