Developing an Ecosystem Health Index to Support Marine Spatial Planning and Sustainable Coastal Management

Seagrass ecosystems are critical components of Kenya's coastal and marine environment, supporting fisheries production, biodiversity conservation, shoreline protection, carbon sequestration, and local livelihoods. Despite their ecological and socio-economic importance, information on ecosystem conditions remains fragmented, limiting their effective integration into marine spatial planning (MSP) and conservation decision-making. This study developed a Seagrass Health Index (SHI) to assess the condition of seagrass ecosystems along the Kenyan coast and provide a standardized framework for ecosystem monitoring and management.

The assessment synthesized ecological datasets collected between 2016 and 2025, including seagrass cover, shoot density, canopy height, and species diversity across major coastal counties. A weighted multi-metric approach was applied to integrate key indicators of ecosystem structure and function. Percentage cover, canopy height, and species richness were scored against ecological thresholds and combined to generate an overall health index categorizing seagrass condition as poor, moderate, good, or excellent. Spatial analyses were undertaken to map ecosystem health patterns and identify areas of conservation and management importance.

Results indicate that Kenyan seagrass ecosystems generally exhibit moderate to good ecological condition, with substantial spatial variability among regions. Counties characterized by extensive meadows dominated by Thalassodendron ciliatum and Thalassia hemprichii recorded higher health scores, reflecting greater structural complexity and ecosystem stability. Areas exposed to intense coastal development, sedimentation, destructive fishing practices, and climate-related stressors exhibited comparatively lower health scores. The health index highlighted important conservation areas associated with fish nursery habitats, blue carbon hotspots, and habitats supporting threatened species such as dugongs (Dugong dugon), green turtles (Chelonia mydas), and the vulnerable seagrass species Zostera capensis.

The Seagrass Health Index provides a practical and scientifically robust tool for ecosystem assessment, enabling the integration of seagrass condition into marine spatial planning, climate adaptation strategies, and blue economy initiatives. The approach offers a baseline for long-term monitoring, supports evidence-based zoning and restoration planning, and contributes to strengthening the conservation and sustainable management of seagrass ecosystems in Kenya.