Western Indian Ocean Marine Science Association

Mangroves of the Western Indian Ocean: Status and Management

Mangroves of the Western Indian Ocean: Status and Management

The WIO mangroves cover about 1 million ha, which is just about 5% of the global mangrove coverage. Almost 90% of these mangroves are found in four countries, namely Mozambique, Madagascar, Tanzania and Kenya; with the most expansive mangrove forests in these countries occurring in deltas and estuaries. This book is an outlook of the mangrove forests in each of the WIO countries. The book analyses distribution of the mangroves, their conditions, utilization patterns, threats and current management intervention to safeguard this critical ecosystem. Although the book is written with a WIO regional focus, the rich information presented herein will also be useful to mangrove enthusiasts outside the region.

The introductory chapter deals with the global distribution of mangroves and then delves into environmental forcing functions influencing mangrove development, which include several atmospheric processes, that have a strong coupling with regional oceanographic processes and geological features. These atmospheric processes include the El Nino Southern Oscillation (ENSO, the Indian Ocean Dipole (IOD), the Paci c Decadal Oscilla- tion (PDO), with accompanying variations in sea level, sea surface temperature (SST), wind and precipitation anomalies and the Australasia monsoonal system, which has a very dominant moderating effect on the climate of the WIO region. Some of the globally critical geomorphological features of the WIO region include the Mozambique Channel and the Mascarene Plateau, as they comprise distinct elements of the geological history of the Indian Ocean basin. The major regional oceanographic processes have a profound influence on the health and productivity of coastal and marine ecosystems as they drive nutrient distribution, moderate salinity regimes, larval migration, and seed dispersal. Sedimentation and water discharge processes also have a profound impact on mangrove development as they bring in nutrients and help in moderating salinity regimes. The introductory chapter also deals with ecosystem linkages including carbon fluxes between mangroves, seagrass beds, and coral reefs. While there has been a very strong proposition of carbon outwelling from mangroves, recent assessments seem to suggest that mangroves are a net carbon sink and thus playing a very important role in moderating the global concentration of GHGs despite their spatially limited extent. Additionally, the introduction further deals with the general ecological and socio-economic importance of mangroves including their valuation.

The next six chapters (two to seven) deal with respective countries with a focus on the biophysical settings influencing mangrove growth and development, historical perspectives of mangrove management in respective countries, species richness and distribution, mangrove associated biodiversity, uses and values, threats (both direct and indirect), respective mangrove management regimes and supporting legislation/policies and lastly proposed recommendations for improved management of these critical ecosystems. Great commonalities exist across different countries in the region in terms of the utilization patterns of mangrove resources with significant populations of coastal communities depending on mangroves for wood products for construction and fuel, while using the ecosystem for fishing activities. Threats to mangroves (both anthropogenic and natural) are fairly similar across the region but to varying extents, with the exception of cyclones as a major threat occurring in the south (Mozambique and Madagascar). Chapter 8 deals with emerging and crosscutting issues including climate change and its associated impacts especially those related to sea level rise, elevated temperature and CO2 and extreme events (e.g. cyclones, flooding and sedimentation). Payments for Ecosystem Services (PES) and the need for vulnerability assessments to determine appropriate mitigation measures are also discussed. The chapter also addresses the unprecedented upsurge in large scale developments in the region ranging from mega transport infrastructure (e.g. ports, railways, roads and airports), agricultural expansion and extractives (oil & gas and mining), which will singly or cumulatively exert even more intense pressure on mangrove ecosystems. Finance as a major driver underpinning these major developments is also discussed. Governance as a major crosscutting driver of change is also addressed and four different scenarios depicting the status of governance across the different countries presented. Recommendations to improve governance regimes and make them more responsive to both traditional and contemporary mangrove management challenges are also elucidated. The concluding chapter deals with a raft of recommendations to support sustainable management of mangrove ecosystems ranging from adoption of tools e.g. spatial planning, integrated coastal zone management (ICZM) to inclusion of mangroves in blue economy strategies of different countries, institutional strengthening (including comprehensive community participation), the need for research into the response of mangroves under different scenarios of climate change and lastly makes a case for regional cooperation at both the research and management level.

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