Christmas Island and Cocos (Keeling) Islands
Far out in the Indian Ocean, Australia administers two other territories with important oceanic reef communities. Cocos (Keeling) consists of two atolls on the Cocos Rise, nearly mid-way between Australia and Sri Lanka. They are dominated by the southeast trade winds and swept by the westward flowing equatorial current most of the year, and are occasionally impacted by tropical cyclones. The main atoll of South Keeling is a little over 15 kilometers across, with a near continuous chain of 27 islands along much of its rim. Horsburgh Island in the north lies apart from the others, and holds a particularly important bird nesting colony. North Keeling (Pulu Keeling) is a much smaller atoll, about 3 kilometers across with a single island almost completely encircling a shallow lagoon. The island itself is of considerable interest, being one of the few in the region with its original vegetation, mostly tall hardwood forest. It is also a very important seabird rookery. Some 525 species of fish have been recorded in the waters around the two atolls.

Christmas Island is a high, mountainous island some 15 kilometers across, reaching a height of 359 meters. It lies about 300 kilometers south of Java. Fringing reefs surround much of it, with narrow reef flats typically 20-200 meters wide before a steep reef slope down to deep oceanic waters. While the reef faunas clearly contain Indian Ocean elements they show a close affinity to Southeast Asia. Diversity is somewhat limited by a moderate range of reef habitats. The island has important seabird nesting colonies, including the endemic Christmas Island frigatebird. Large numbers of crabs are also noted, including 13 land crabs, the best known of which are the red crabs Gecarcoidea natalis, which have a population of some 120 million individuals and undertake a famous annual mass migration to spawn in the sea. The resident population of some 2 000 people originally came to the island to mine its large phosphate deposits, and this continues, although it is strictly regulated. More recently a hotel and casino complex has been developed, drawing tourists from Southeast Asia. Over 60 percent of the island and much of the fringing reef is protected in a national park.

Western Australia (WA) has many coral reefs scattered along 3,000 km of coast with a wide variety of reef types, predominantly fringing reefs (including Ningaloo, the world’s largest) and patch reefs. Most of the reefs are remote from population centres, while some reefs are also remote from land (e.g. over 300 km offshore). The majority of the reefs are near shore in embayments or islands around the coast. The Houtman Abrolhos Islands form the most southern reef system in the Indian Ocean. Western Australia is developing a system of marine parks and reserves to incorporate the large number of reefs not currently within MPAs. Some protection, however, is provided under a number of general Acts (i.e. State Fisheries Act, Environmental Protection Act, Wildlife Conservation Act).

Australia also administers the Cocos (Keeling) Islands and Christmas Island, located south of Indonesia in the Indian Ocean. The reefs of Cocos (Keeling) Islands have not been affected by the recent major coral bleaching events and remain in near pristine condition.

The Northern Territory and the Gulf of Carpentaria include many reefs within coastal waters, but their extent is yet to be fully explored. In 2003, a large new coral reef was discovered in waters of the Gulf of Carpentaria that were previously considered too warm and muddy for such ecosystems. Due to the poorly mapped and remote nature of reefs in this area, there have been few monitoring or baseline surveys, thus little is known of their overall status.

The Coral Sea Islands Territory consists of scattered islands in an area of approximately 780,000 km² of the Coral Sea, extending eastwards from the outer edge of the GBR. The majority of Coral Sea reefs are in Australian territorial waters. These include several MPAs: the Coringa-Herald; Lihou Reef; Elizabeth and Middleton Reefs National Nature Reserves; and Lord Howe Island (New South Wales Marine Parks Authority). Elizabeth and Middleton Reefs and those around Lord Howe Island, 150 km to the south, are the most southern coral reefs in the world and come under the influence of the warm East Australia Current. Monitoring has been limited to a few surveys with the most recent in 2003/04. The coastal Solitary Islands in northern New South Wales are included in this broad category, although these are transient coral communities. These reefs have abundant hard coral cover. The Solitary Islands Marine Park was established in 1991 as a multiple use marine park. The first monitoring was implemented in 2000, and in 2002 the area of reef within the most protected zone (sanctuary zone: no fishing or anchoring permitted) was increased considerably.

Western Australia


-Western Australian reefs include extensive coastal reef systems and isolated and remote offshore oceanic reefs and islands;
-Most reefs are far from urban centres and are in relatively good condition. New management plans have been introduced and more are being developed;

There are approximately 3800 km² of mangrove and saltmarsh habitat along the GBR coast, with this area remaining relatively stable. However these mangrove forests are only remnants of more extensive forests that have been progressively cleared since European settlement started 200 years ago. Some localised losses of mangroves have occurred and the main pressures are from continued coastal development.GBR seagrasses are highly variable and are particularly affected by storms and floods. There are approximately 46 000 km2 of deep and shallow seagrass beds with no apparent widespread declines, although there have been localised losses. Seagrasses are affected by declining water quality, coastal development and localised impacts.

Ningaloo Reef is the longest fringing reef in the world (280 km) and is 1000 km north of Perth where temperate and tropical currents converge in the Ningaloo region. This has resulted in high coral reef diversity with more than 500 fish, 250 coral and 600 mollusc species. Ningaloo Marine Park (which includes State and Commonwealth waters) was established in 1987 and the State waters of the marine park were extended in 2004 along with the inclusion of the Muiron Islands Marine Management Area. Combined, the marine reserves cover 5355 km2 and are managed by the WA and Australian Governments. The WA Government released a new management plan for the State section in 2005 with increases in the area of ‘sanctuary zones’ to 34% of the park area. DEC are implementing a long-term monitoring program that will help improve the science underpinning the management of Ningaloo Marine Park.

The Coral Sea
Due east of the Great Barrier Reef and the Torres Strait, Australia holds jurisdiction of a large number of reef formations lying some distance off the continental shelf. In the far north close to Papua New Guinea these include the Portlock Reefs and Eastern Fields. The majority of the remainder are located in an area known as the Coral Sea Shelf. Most are atoll formations, stretching from Osprey Reef in the north to Saumarez Reef in the south. Some are substantial in area – Lihou Reef is a long oval reef structure totalling nearly 2 500 square kilometers. In addition, a number of other reefs lie further south or east, off the Coral Sea Shelf, including Mellish, Frederick, Kenn, Wreck and Cato Reefs.

Torres Strait and the Great Barrier Reef
The largest coral reef system in the world runs along the northeastern coastline of Australia, stretching from the Warrior Reefs in the northern Torres Strait for well over 2 000 kilometers to the Capricorn-Bunker Group of reefs and islands in the south. Although many of the reefs which make up this system form part of a true barrier reef following the continental shelf on its outermost edge, the Great Barrier Reef is actually a highly complex system including nearly 3 000 separate reefs and coral shoals, as well as high islands with fringing reef systems.

Although best seen as a continuous reef complex, it is possible to distinguish a number of ecological regions within the Great Barrier Reef.

Torres Strait
In the far north of Australia the continental shelf forms a wide connecting platform across the Torres Strait to Papua New Guinea. As most of the islands in the Torres Strait fall under Australian jurisdiction so do the reefs and waters of the Strait. There is considerable freshwater and sediment input from the Papua New Guinea coastline, however there are several very extensive platform reefs across the relatively shallow waters of the Strait. The westernmost areas have the shallowest and most turbid waters. A large chain of reefs runs between Prince of Wales Island and Moa Island. Like other reefs in the area, these show a very clear east-west alignment associated with the high velocity tidal currents running through the area. The Warrior Reefs further to the north and east run in a chain towards the coastal town of Daru in Papua New Guinea. Sediment loads are high in this area, and much of the shallow surface of these reefs is dominated by soft muds, although they are fringed by coral on their eastern margins. Finally there is a wide area of platform reefs around Darnley Island, stretching out towards the edge of the continental shelf and the near continuous line of reefs which mark the northern edge of the outer barrier reef.

Northern section
Due east of Cape York the continental shelf remains wide, but it then narrows rapidly towards Raine Island and continues as a platform typically less than 50 kilometers wide. The most distinctive feature of this sector of the Great Barrier Reef is the well developed ribbon-type barrier reefs on the outer edge: long narrow ribbon reefs typically less than 500 meters wide but extending up to 25 kilometers in length and separated by relatively narrow passes. They are located right on the edge of the continental shelf, and depths drop rapidly to over 1 000 meters only a few hundred meters from the eastern edges of some reefs. For about 80 kilometers, in the northernmost sector of these ribbon reefs, there are spectacular deltaic formations in the channels between the reefs. Rather like river deltas, these have been formed in the calmer waters behind the reef by the deposition of sediments from the powerful currents which flow between the reefs. The banks of sediments have then formed a substrate for new reef development.

Inshore of the ribbon reefs there are well developed mid-shelf and inner shelf reefs, while there are also wide areas of submerged Halimeda-dominated shoals and banks. This is one of the only areas where there are fringing reefs directly adjacent to the mainland coast, although coral cover and diversity are limited. Raine Island just off the continental shelf has the largest nesting populations of green turtles in the world as well as some of the most important seabird rookeries. There are only a few high islands on the continental shelf, notably the Flinders Group and Lizard Island. These have important and extensive fringing reefs.

Central section
This section extends from Mossman in the north to the barrier reef offshore from the Whitsunday and Lindeman Islands. Over this area the continental shelf gradually widens, with reef development largely restricted to its outer third. Closer to the mainland the waters are subject to considerable fluctuations in turbidity and salinity due to the seasonal flooding of rivers. The reefs in this area are younger than those to the north. Many have lower and less extensive reef flats, and coral cays are largely absent, while their outer reef crests are often only clearly developed on the windward southeastern margins. Overall the reefs are less tightly packed and hence do not form such a continuous barrier. The main reefs are also set back a little from the true edge of the continental shelf, although there are several reefal shoals close to the outer shelf margin which rise to within 10 meters or so of the surface and have active coral growth. Over relatively short geological timescales these could evolve into ribbon reef systems similar to those observed to the north. In addition to the barrier reef structures there are important fringing reef communities associated with a number of high island groups, notably the Palm Islands and the Whitsunday and Lindeman Islands to the south.

The Swain and Pompey Complexes
This is the sector of the Great Barrier Reef where the continental shelf is at its widest and the main reefs are furthest from shore. The Pompey Complex has a number of submerged reefs on the edge of the continental shelf. However, about 10 kilometers back from this edge is a vast and complex array of very large reef platforms separated by countless meandering channels making a nearly solid mass of reefs nearly 200 kilometers in length and up to 20 kilometers wide. The high tidal range in this area drives strong currents reaching up to 10 knots, which scour many of the channels between the reefs. Within the lagoons of individual reefs there are complex patterns of channels and mid-reef coral ridges. To the south the Swain Reefs form a second distinctive complex, dominated by many much smaller and even more closely spaced reefs where large numbers of small coral cays have developed. Inshore of the main Swain and Pompey Complexes reef development is limited, however there are some reefs close to the mainland and associated with island groups such as the Northumberland Islands and Percy Isles.

The Capricorn-Bunker Group
South of the Swain Reefs Complex the continental shelf rapidly narrows again and the southernmost reefs of the Great Barrier Reef, the Capricorn-Bunker Group, lie a little over 50 kilometers offshore. This is a relatively small complex, well defined with steeply sloping reef edges and deep inter-reefal waters. There are several well developed coral cays, including One Tree Island and Heron Island, which are among the best known reefs of the entire Great Barrier Reef. These reefs actually traverse the tropic of Capricorn and cooler waters are largely responsible for the lower coral diversities found here.

The Great Barrier Reef (GBR) is the major Australian reef structure, with 3,000 fringing, submerged, platform and barrier reefs spread over 2,700km of the Queensland continental shelf, from the reefs of the Torres Strait and Papua New Guinea to 23°S. All of the reefs are contained within the GBR Marine Park (339,750km²), which is also a World Heritage Site. There are also remote reefs in the Coral Sea to the east and south of the GBR, and also extensive coral reefs off the coast of Western Australia, including 4,000km² at Ningaloo Reef. Australia’s EEZ includes reefs well out into the Indian Ocean, as far as the longitude of western Sumatra.

High latitude reefs
South of the Great Barrier Reef there are several reefs and coral communities lying at high latitudes. The south flowing East Australia Current has an important role to play in maintaining these communities, bringing warm waters as well as the potential for new larval recruits to settle on the reefs.

Lord Howe Island is a high volcanic island with a reef structure extending for some 6 kilometers along its western side. This is the most southerly coral reef in the world, lying beyond 31°S. Elizabeth and Middleton Reefs are platform reefs lying on older volcanic seamounts which form a chain to the north of Lord Howe Island. On the mainland coast there are no true coral reefs. Flinders Reef, east of Brisbane, is a sandstone structure, but has been colonized by a range of tropical corals and other species. Further south, the Solitary Islands also have important coral communities. There are also many smaller benthic communities with coral reef species elsewhere along the coastline of South Queensland and northern New South Wales.

North Australia
North of Port Headland and Eighty Mile Beach the continental shelf of Australia widens considerably, while the coastline of Indonesia and East Timor forms a northern boundary enclosing the Timor Sea. To the east of Darwin this continental shelf widens further still and connects Australia to New Guinea across the Arafura Sea and the Gulf of Carpentaria. This is Australia’s least known and least populated coastline. Wide areas are dominated by an intricate network of rivers and channels with extensive mangrove communities. To the east, in the Arafura Sea, the waters are shallow and turbid and there is little reef development. Fringing reefs are reported further west, but are very poorly described.The only reefs in this region which have received attention are those lying in the northwest on the continental shelf edge or just beyond.