It has between 400 and 500 species of marine algae. Red and brown algae dominate the inshore part of the Reef while red and green algae predominate in offshore areas. The Park has the most extensive beds of Halimeda algae in the world.
Mangroves are extremely important as a spawning ground and nursery for many Reef species. The Park is home to 37 mangrove varieties, representing 57 per cent of all the world's mangroves.
Lush coastal vegetation
The Park's 15 species of seagrasses are also very important to high profile animals such as turtles and dugongs.
The Great Barrier Reef Marine Park includes about 900 islands. Of these, 618 are continental islands and 300 are coral cays, of which 230 are vegetated.
Of 2195 plant species found on the 618 continental islands of the Reef, only three are found nowhere else. There are between 300 and 350 species on coral cays in the north of the Park and 120 species in the south.
The Whitsunday Islands are the most botanically diverse area in the Park with 1141 species recorded. More than 70 species in the Park are listed as rare or threatened under Queensland and Commonwealth legislation, and in the IUCN Red Book.