GREAT BARRIER REEF
// Outlook Report 2014
Figure 3.11 examples of areas in catchment basins that support the Great Barrier reef
Examples of areas of the Mulgrave-Russell, Haughton, Fitzroy and Baffle basins that support the Region. The darker areas shown are of higher importance to the healthy functioning of the Great Barrier Reef ecosystem because of their proximity to and connectivity with the Great Barrier Reef. The analysis takes into account wetlands and areas that are frequently inundated or flooded, as well as areas influenced by tidal processes and storm surges. It represents the surface level hydrology only and does not include groundwater. Source: Great Barrier Reef Marine Park Authority 2014216
to the marine system (Section 3.4.10). Figure 3.11 presents preliminary maps of the relative importance of areas within four basins of the Great Barrier Reef catchment to the healthy functioning of the marine ecosystem. They illustrate the particular importance of tidal and riparian habitats to the Region. Past broadscale land clearing, principally in the southern two-thirds of the Great Barrier Reef catchment, has significantly affected each of the supporting terrestrial habitats. Clearing began in the 1870s and was undertaken to allow more intensive agricultural use. It further increased when intensive cropping on the coastal floodplain began in the early 1900s and again in the 1930s and 1940s when heavy machinery made clearing easier. The rate of clearing continued to increase until the late 1990s.189 Ongoing agricultural use of these habitats also affects their ability to support the Reef ecosystem. The majority of vegetation in the catchment now is classed as ‘non-remnant’, that is it has been modified to the extent that its natural ecological function has been modified or lost. This classification includes areas of regrowth from past clearing, some of which continues to provide functions that support the Region189. Changes in the extent of each habitat within the Great Barrier Reef catchment are summarised in Table 3.1 and mapped in Figure 3.12. The resultant loss and modification of habitats has led to significant increases in pollutants, principally nutrients and sediments, entering the Great Barrier Reef lagoon189 which has reduced the ecosystem’s ability to bounce back after impacts, especially in southern inshore areas.217 In addition, the loss of freshwater coastal habitats has affected some ecological functions and numerous marine species, including the freshwater sawfish which is now threatened, in part, due to habitat loss.218
Past broadscale land clearing has affected habitats that support the Reef.