Figure 2.3 Major habitats of the Great Barrier Reef Region
A wide variety of habitats make up the Great Barrier Reef ecosystem. The most pronounced variation is across the continental shelf from the inshore coastal habitats, such as mangroves and beaches, eastwards to the continental slope and deep ocean.
Some islands have been affected by cyclones, pests, and the impacts of use.
Several species of terrestrial plants and animals are endemic to Great Barrier Reef islands (such as Pisonia forests24).25 Islands also provide important nesting grounds for a number of marine species such as marine turtles and seabirds.26 There is limited new information and monitoring of the condition of most islands. Recent severe cyclones27, invasive pests28 and weeds29, marine debris, and changes driven by coastal development (Section 6.4) have affected the condition of some islands. Islands are also considered vulnerable to climate change.25,30,31
2.3.2 Mainland beaches and coastlines
The beaches and coastlines of the Great Barrier Reef ecosystem stretch approximately 2300 kilometres along the mainland coast of Queensland. Sandy shores typically occur on the exposed coastline and are generally a highly dynamic habitat. They support a wide range of species including providing nesting and staging grounds for shorebirds32 and marine turtles33. Muddy shores are generally adjacent to river mouths and estuaries in sheltered areas. They act as depositional areas for sediments and nutrients discharged from the catchment or transported along the coast. Rocky coasts are intermittently distributed, providing habitat for many sessile species such as oysters. Beaches and coastlines in the northern area remain relatively unaltered, except for marine debris brought in by currents and tides, and extreme weather events such as cyclones. Structures such as marinas, groynes and port infrastructure have heavily modified some coastline habitats at a local scale and affected local coastal processes. Sediment supply to some beaches is disrupted by artificial barriers to flow (for example dams and weirs) and mangrove forests have replaced beaches where fine sediments have increased.34
Some beaches and coastlines have been modified especially around urban centres and ports.
2.3.3 Mangrove forests
Mangrove forests are an intertidal habitat of trees and shrubs covering an estimated 2070 square kilometres in and adjacent to the Region.34 The habitat occurs in sheltered areas where fine sediments accumulate and where there is inundation by seawater during the tidal cycle.35 The mangrove forests of the Great Barrier Reef are very diverse36,37,38, with the highest diversity in the far north.38 Mangrove forests are an integral part of the Reef ecosystem, providing essential structure and habitat for a range of terrestrial, marine and intertidal species. They play a critical role as: a source of primary production and carbon sequestration;
Mangrove forests remain relatively stable and abundance is being maintained.
Mangrove forests are habitat for terrestrial, marine and intertidal species
© Chris Jones