GREAT BARRIER REEF
// Outlook Report 2014
periods of low sea level.61,67 In addition, ‘blue holes’ — deep circular depressions with steep sides — are a rare karstic landform in the Region.68 Submarine canyons — occur along the shelf edge (Figure 4.4) and can modify oceanography to produce upwellings.69 They also preserve information about sea level change, and sediment and tectonic movements.70,71,72 turbidite deposits — at the base of the continental shelf (Figure 4.4). They are the result of sediment transport from the The Blue Hole at Cockatoo Reef in the Pompey Complex, east of Mackay continental shelf and are responsible for distributing vast amounts of sediment into the deep ocean. They provide historical records about sedimentation in the adjacent shelf area, tectonic movements and responses to sea level change.73 Almost all geomorphological processes remain intact. Examples of all stages of reef development remain although the overall health of reefs, especially in the southern two-thirds of the property, has declined. Although little is known about geomorphological features such as palaeochannels, karstic features, submarine canyons and turbidite deposits, their depth and distance from shore mean they are likely to be rarely affected by direct use or flow-on effects from the catchment.
4.5.3 Ecological and biological processes
Most geomorphic, physical, chemical and ecological processes remain in good condition but some are deteriorating, especially in the inshore southern two-thirds of the Region. Processes associated with groups of species in decline (for example, corals and seagrasses) have likely also declined. Particularly in the inshore southern two-thirds, processes such as connectivity, nutrient cycling and sedimentation have deteriorated, principally associated with adjacent land-based activities. There is increasing evidence of intensified flow and accelerated warming in the East Australian Current.74 The diversity of the Reef ecosystem reflects the maturity of an ecosystem that has evolved over millennia.75 The Region’s species diversity remains high, but some species are in poor condition, especially inshore in the southern two-thirds of the Region. Birds continue to play a role in seed dispersal and plant colonisation on cays and continental islands.76,77 Introduced weeds have affected the native vegetation on a number of islands within the Region.78 Halimeda banks are an example of active calcification and accretion over thousands of years. They are poorly studied, but are likely to be in very good condition given their isolation from land-based impacts and their level of zoning protection from trawling. The strong ongoing links between Aboriginal and Torres Strait Islanders and their sea country are recognised in the description of the property’s outstanding universal value.50 Traditional Owners with connections to the Great Barrier Reef maintain links to their sea country in the Region. Many Indigenous heritage values are under pressure, including sites of significance, stories, songlines, totems and structures (Section 4.2).
Traditional Owners with connections to the Great Barrier Reef maintain their ongoing links to sea country. Some ecosystem processes such as sedimentation, nutrient cycling and recruitment are declining.
4.5.4 Habitats for conservation of biodiversity