Phase V – Ecosystem based protection of the coastal zone: the effectiveness of seagrass meadows in coastal erosion management

Coastal ecosystems hold a specific, rich and unique biodiversity. They provide a variety of ecosystem services, which are directly linked to human wellbeing and environmental health. Anthropogenic pressures are, however, a threat to coastal ecosystems, and a rising sea level is posing further risks. The project aimed to document how the presence or absence of seagrass meadows influences biodiversity and sediment dynamics in the coastal zone, and how this drives the multi-functionality of the coastal zone. In the course of project implementation, the perception of the communities on the importance of seagrass meadows in terms of cultural functions, socio-economic functions and other immaterial services was assessed (Work Package 1). Two manuscripts were developed from this work package, and have been submitted for publication consideration. Given the widespread lack of knowledge with regard to how extensive seagrass meadows are in the WIO region, the inventory and mapping of seagrass meadows was carried out (as Work Package 2) in southern Mozambique (Maputo and Inhambane Provinces) and the entire coast of Tanzania (including Mafia, Unguja and Pemba Islands) to serve as the basis for developing monitoring and management strategies. The project managed to develop Geographic Information System (GIS) maps for the studied areas. Two manuscripts on seagrass mapping are in preparation as outputs.

To understand the multifunctional effects of implementing ecosystem-based actions, the secondary effects of biodiversity from the interplay between the shallow coastal zone and the terrestrial environment was evaluated (Work Package 3). Areas with and without intertidal seagrasses were compared to assess the terrestrial diversity (flora and fauna (macroinvertebrates)), and abiotic parameters (sediment grain size, organic matter content, carbonate content and sediment nutrients (N&P). These parameters will be coupled with the stable isotope signatures of the sediment samples to better understand the functions of intertidal seagrass meadows in supporting the terrestrial environment. Two manuscripts are in preparation as outputs.

The effect of seagrass presence on sediment movement, water currents and biodiversity was assessed (Work Package 4). One manuscript is being prepared. To increase understanding on how to quantify the effects of ecosystem based coastal protection on long-term beach evolution, this project is in the process of building a Simulating Waves Nearshore (SWAN) model (Work Package 5). This model will help in the quantification of the contribution of the seagrass meadow to reducing the wave energy as well as provide spatial distribution maps of the wave energy wave, which will be used to identify areas and the required method for seagrass restoration.

The project also investigated the best practices for seagrass restoration with a view to providing technical guidelines on how seagrass can be restored in the WIO and informing evidence-based decision making for sustainable coastal management (Work Package 6). Findings from this work package produced two journal articles. Lastly, through Work Package 7, the information generated from this project was disseminated to various stakeholders to ensure awareness raising, community participation and evidence-based decision making. Information regarding the project team, activities and outputs was also communicated to a wider audience using the project website (https://marinescience2.wixsite.com/seagrassprotect).