Mangroves

Mangroves are forests comprised of saline-adapted trees and shrubs that grow in the inter-tidal regions of the tropical and subtropical coastlines forming a unique wetland ecosystem at the interface of the land and sea^{[1, 2]}. Coastal Africa hosts 20% of the world’s mangroves, offering coastal communities much-needed protection against storms and coastal erosion, while harboring high levels of biodiversity and storing exceptionally high carbon compared to most forest types^[3-6]. Mangrove ecosystems in Coastal Africa are under enormous pressure from both the ocean and the land. On the land side, deforestation is high, driven by commodity-based agriculture including livestock, illegal artisanal gold mining, illegal logging for fuel and timber and human settlement^[7-9]. On the ocean side, climate change is having a major impact on mangroves through sea level rise, changing ocean currents, increased storms, increased temperature, changes in precipitation, and elevated CO2 levels^[7-9]. These anthropogenic and climate change processes impact the structure, distribution, biodiversity, and carbon sequestration potential of mangrove ecosystems leaving the complex mangrove-based socio-ecological systems at risk^[10].

Adaptations and Distribution:

• Salt Tolerance: Mangroves are halophytes, capable of coping with saltwater immersion. They have a complex salt filtration system.
• Root Systems: Prop roots stabilize them in waterlogged mud and protect against wave action.
• Low-Oxygen Survival: They thrive in the upper half of the intertidal zone, where oxygen levels are low.

Ecological Importance:

• Habitat and Biodiversity: Mangrove forests serve as vital habitats for diverse aquatic species. Fish, crabs, birds, and other organisms find refuge among their roots.
• Coastal Protection: Mangroves act as natural buffers, reducing the impact of storms, waves, and erosion on shorelines.
• Carbon Sequestration: They store significant amounts of carbon, mitigating climate change.
• Nutrient Cycling: Fallen leaves and detritus enrich coastal waters, supporting marine food webs.

Challenges and Conservation:

• Deforestation: Human activities (urbanization, aquaculture, and logging) threaten mangroves. The global annual deforestation rate is estimated at 0.16%.
• Degradation: Remaining mangroves face degradation due to pollution and habitat alteration.
• Conservation Efforts: Initiatives like the Global Mangrove Watch monitor mangrove extent and promote restoration. Local communities play a crucial role in protecting these ecosystems.

References

1. Feller, I.C., et al., Biocomplexity in mangrove ecosystems. Annual review of marine science, 2010. 2: p. 395-417.2.
2. Aheto, D.W., et al., A survey of the benthic macrofauna and fish species assemblages in a mangrove habitatin Ghana. West African Journal of Applied Ecology, 2014. 22(1): p. 1–15-1–15.3.
3. Quisthoudt, K., et al., Disentangling the effects of global climate and regional land-use change on thecurrent and future distribution of mangroves in South Africa. Biodiversity and Conservation, 2013. 22(6-7):p. 1369-1390.4.
4. Sinsin, C.B.L., et al., Potential climate change induced modifications in mangrove ecosystems: a case studyin Benin, West Africa. Environment Development and Sustainability, 2022. 24(4): p. 4901-4917.5.
5. Duguma, L., et al., Drivers and Threats Affecting Mangrove Forest Dynamics in Ghana and The Gambia.Women Shellfishers and Food Security Project. World Agroforestry (ICRAF), Nairobi, Kenya and CoastalResources Center, Graduate School of Oceanography, University of Rhode Island. Narragansett, RI, USA.WSFS2022_01_CRC. 53 pp. 2022.6.
6. TFS, The United Republic of Tanzania Tanzania Forest Service Agency (TFS). Tanzania’s Mangroves.https://www.tfs.go.tz/index.php/en/forests/tanzanias-mangroves. accessed 20 June 2023. . 2023.7.
7. Sippo, J.Z., et al., Mangrove mortality in a changing climate: An overview. Estuarine Coastal and ShelfScience, 2018. 215: p. 241-249.8.
8. Wang, Y.S. and J.D. Gu, Ecological responses, adaptation and mechanisms of mangrove wetland ecosystemto global climate change and anthropogenic activities. International Biodeterioration & Biodegradation, 2021. 162.9.
9. Ward, R.D., et al., Impacts of climate change on mangrove ecosystems: a region by region overview.Ecosystem Health and Sustainability 2016. 2(4).10.
10. Babiker, M., G. Berndes, K. Blok, B. Cohen, A. Cowie, O. Geden, V. Ginzburg, A. Leip, P. Smith, M. Sugiyama,F. Yamba., Cross-sectoral perspectives. In IPCC, 2022: Climate Change 2022: Mitigation of Climate Change.Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on ClimateChange [P.R. Shukla, J. Skea, R. Slade, A. Al Khourdajie, R. van Diemen, D. McCollum, M. Pathak, S. Some,P. Vyas, R. Fradera, M. Belkacemi, A. Hasija, G. Lisboa, S. Luz, J. Malley, (eds.)]. Cambridge University Press,Cambridge, UK and New York, NY, USA. doi: 10.1017/9781009157926.005. 2022.