Seagrasses are a functional group of 60 species of underwater marine flowering plants that occur in proximity to, and are ecologically linked with, coral reefs, mangroves, salt marshes, bivalve reefs and other marine habitats. They provide habitat for fish and shellfish and act as nursery areas. They also perform important physical functions such as filtering coastal waters, dissipating wave energy and anchoring sediments. Seagrasses are also the primary food for dugongs (Dugong dugon) and green sea turtles (Chelonia mydas).

Six global bioregions of seagrasses are recognized: four temperate and two tropical. The tropical Indo-Pacific bioregion has the highest seagrass diversity in the world, with as many as 24 species. There is considerable variation in the diversity of seagrasses within the Mozambique Channel. Twelve species have been recorded in Mozambique, nine in Madagascar and ten in the Comoros and Seychelles.

Seagrass habitat loss has been attributed to both natural and human disturbances. Natural disturbances include hurricanes, cyclones, earthquakes, floods, heavy rains, strong water movements, disease and herbivore grazing. Human activities that affect seagrasses are mostly those that alter the water quality and clarity such as nutrient and sediment loading from runoff and sewage disposal, dredging and filling, pollution and upland development or deforestation. Specific impacts on seagrass identified in the western Indian Ocean include destructive fishing methods (trawling or dynamite fishing), domestic and industrial waste disposal, unsuitable farming methods and wastes from oil tankers.

This work aimed to map seagrass beds of the Comoros and Northern Madagascar in collaboration with local communities using the SeagrassWatch protocol.