Spatial Risk Assessment for Coastal Seagrass Habitats in the Great Barrier Reef World Heritage Area: a case study of the dry and wet tropics

[Extract] Seagrasses are specialised marine flowering plants that grow in the estuary and nearshore environments of most of the world’s continents. There are relatively few species globally (about 60) and these are grouped into just 13 Genera and 5 Families. Most are entirely marine although some species (such as Enhalus acoroides) cannot reproduce unless emergent at low tide. There are 15 species of seagrass in the GBRWHA. The high diversity of seagrass reflects the variety of habitats, the extensive bays, estuaries, coasts, lagoons and reefs that are available for seagrass colonization. More than 5,000 km2 of coastal seagrass meadows are in eastern Queensland waters shallower than 15 m and it is expected that approximately 40,000km2 of the seafloor in the GBRWHA deeper than 15 m has some seagrass (Coles et al. 2007). This represents about 36% of the total recorded area of seagrass in Australia.