Benthic Ecological Survey in Coastal waters of Pwani and Tanga Regions

This report presents the findings of a Benthic Ecological Survey (BES) conducted by Asasi ya Uwezeshaji Tanzania (ASUTA) along the northern coast of mainland Tanzania, covering the coastal waters of Bagamoyo, Pangani, Tanga, and Mkinga Districts. Carried out between September and October 2023 as part of the USAID Heshimu Bahari project, the survey aimed to generate high-resolution data on the composition of benthic habitats—such as coral reefs, seagrass meadows, algae beds, and sandy substrates—in waters shallower than 50 meters. Using a systematic grid-based approach and underwater photography, the survey captured over 2,100 georeferenced images, later analyzed via CoralNet's AI-assisted annotation platform. The results reveal significant spatial variability in benthic community composition, depth-related distribution patterns, and ecological hotspots and coldspots for seagrass, corals, and algae. This is the first comprehensive benthic dataset for Tanzania’s northern coastal waters, offering essential baseline information to inform marine spatial planning and the design of Marine Managed Areas (MMAs), including no-take/ fishery replenishment zones (FRZs). The report also provides methodological recommendations for future benthic surveys in Tanzania and the broader Western Indian Ocean region.