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Australia's New Marine Parks

Two new marine parks around Christmas Island and the Cocos (Keeling) Islands herald protection for fragile and beautiful ecosystems

Christmas Island lies in the Indian Ocean, 1550km north-west of Exmouth, WA, and 350km from the south coast of Java, Indonesia. The Cocos (Keeling) Islands lie 980km west of Christmas Island. They are both Australian external territories, known collectively as the Indian Ocean Territories, under the legal and international jurisdiction of the federal government.

The Cocos (Keeling) Islands were discovered in 1609 and, after annexation by Britain in 1857, formed part of the Colony of Singapore. The islands were transferred to the Commonwealth of Australia on 23 November 1955. Christmas Island was also part of Britain’s Singapore colony until it was acquired by Australia on 1 October 1958 for an ex gratia payment of 2,800,000 pounds to compensate for lost revenue from phosphate royalties.

Both territories are administered by the Department of Infrastructure, Transport, Regional Development and Communications through Administrators appointed by the Governor-General. Many public services, including health, education and policing, are provided by the state of Western Australia, and Western Australian law applies unless overridden by federal law.

All vessels entering the territories must go through quarantine, customs and immigration formalities. Passports and visas are not required when travelling to them from the Australian mainland. However, photographic identification, such as an Australian driver’s licence, a valid passport or proof of age card, must be produced for each passenger (including children). Normal Australian customs and immigration procedures apply when entering the islands from outside Australia. A passport is necessary, and a visa may be required. Immigration formalities are also applied on departure.

The Department of Agriculture is the border agency charged with protecting the environment and maintaining the quarantine integrity of the islands. Certain products are prohibited on the islands, while other items may require some form of treatment before they can be released. The Department has a base on Christmas Island but its functions, as well as customs and immigration matters, are handled on the Cocos (Keeling) Islands by the Australian Federal Police.


Under the United Nations Convention on the Law of the Sea (UNCLOS), Australia has jurisdiction over an Exclusive Economic Zone (EEZ) that extends 200 nautical miles from its mainland and external territory coastlines. Within the EEZ, Australia has sovereign rights to explore and exploit the fishery, mineral and petroleum resources and other economic activity. Although Christmas Island and the Cocos (Keeling) Islands are remote and relatively small, Australia is entitled under UNCLOS to an EEZ around them of 200NM. In the case of Christmas Island, this has been modified because of its close proximity to Indonesia and the northern boundary is an east-west median line established by treaty in 1997.


Christmas Island has a resident population of just over 2000 with an ethnic composition of 60 per cent Chinese, 25 per cent Malay and 15 per cent European, reflecting historical origins. The main settlement is Flying Fish Cove on the northern tip of the island. The largest contributor to the island economy is the mining of phosphate while other activities are tourism, small-scale commercial fishing and the provision of government services including the operation of the Immigration Detention Centre.

The population of the Cocos (Keeling) Islands is around 600, the majority of whom are Cocos Malays living on Home Island. West Island accommodates a small enclave comprising employees of various government departments, contractors and their families. A growing number of small businesses provide a range of goods and services to the community, often under contract to the Australian Government. The biggest employer in the private sector is the Cocos Islands Cooperative Society Ltd, which manages the supermarkets and the public transport service, as well as construction, stevedoring and lighterage operations. A modest tourist industry focuses on water-based or nature activities.


The territories are located in the North East Indian Ocean, a region bounded by the Java Trench in the north, the Ninetyeast Ridge in the west, the Australian Continental margin in the east and Broken Ridge to the south.

The Java Trench stretches 3200km from the Lesser Sunda Islands around the south coast of Sumatra to the Andaman Islands and forms the boundary between the Indo-Australian Plate and Eurasian (Sunda) Plate. With a maximum depth of 7290m, it is the deepest point in the Indian Ocean. The Ninetyeast Ridge runs south from the Bay of Bengal for 5000km along the 90th meridian (hence its name) and divides the Indian Ocean roughly in half along the junction of the Indian and Australian Plates. Broken Ridge is an oceanic plateau extending 1200km from the southern end of the Ninetyeast Ridge towards the south-western corner of Australia. It is up to 400km wide and reaches a maximum depth of 1000m.

Although they share the same oceanic region, the islands’ geomorphology is fundamentally different. Volcanism has long ceased but the area is still tectonically active. Lying close to the Java Trench, Christmas Island maintains a history of gradual uplift as the plate beneath it bows upward. In contrast, the Cocos (Keeling) Islands’ proximity to the Ninetyeast Ridge has exposed it to more dynamic cycles of uplift and submergence as the Indian Plate slides north along the Australian Plate.

Fringing reefs protect most of the Cocos (Keeling) Islands


The seafloor around Christmas Island has three distinct subregions — the Central Ridge, the Wharton Basin and the Cocos Basin.

To the east of the Central Ridge lies the Wharton Basin, an abyssal plain spanning 145,500sqkm at depths of between 3500–6420m. Numerous seamounts rise from the plain to heights up to 3000m. They are mostly steep-sided cones with base diameters of 20–30km.

The Cocos Basin covers 62,480sq km to west of the Central Ridge. It comprises a relatively featureless abyssal plain at depths of between 2000–6000m. A small cluster of conical seamounts occurs on its western boundary, with diameters less than 25km and elevations up to 3000m.


The seafloor around the Cocos (Keeling) Islands has four distinct subregions — the Cocos Volcanic Field, Investigator Ridge, the East Cocos Abyssal Plain and the West Cocos Abyssal Plain.

The Cocos Volcanic Field comprises a large cluster of seamounts across 167,000sqkm. These were formed by volcanic activity about 60-90 million years ago. The two island atolls evolved as coral caps between 500 and 1000m thick over a large basalt guyot with a 70km base at a depth of 5000m. The largest of the other seamounts is Muirfield (130km south-west of South Cocos), which rises from 4000m to 17m below the sea surface. Large areas of abyssal plain separate the seamounts at depths of 4500-5900m.

Investigator Ridge is the most significant seabed feature in the Cocos (Keeling) territory. The ridge rises about 2500m from the Cocos Basin abyssal plain (at 5500m) and stretches south from Sumatra along a fracture zone for 1800km, bisecting the territory to the east of the islands. It has a steep west-facing scarp and a gentler eastern slope, with deep troughs on either side. The trenches vary in depth and profile; those to the east are steep-sided and plunge 6400m, while those in the west have slightly lower relief and reach a maximum depth of 5900m.

The 93,780sq km East Cocos Abyssal Plain lies to the east of Investigator Ridge. It is characterised by a deep abyssal plain ranging in depth from 3600–6400m, with an isolated group of four seamounts belonging to the Vening-Meinsz chain that encroaches from outside the EEZ. The highest peak reaches to 1050m below the sea surface, while the summits of lesser peaks lie much deeper.

The West Cocos Abyssal Plain spans 145,250sq km to the west and north of the Cocos (Keeling) Islands. The majority of this subregion consists of a deep abyssal plain of uniform topography in depths of 5000–6000m, with numerous basins and several low hills no higher than 700m elevation.


The Indian Ocean Territories lie in deep water in the path of the South Equatorial Current (SEC). The SEC originates in the Western Pacific and is dispersed by New Guinea and the eastern Indonesian archipelago as it flows west through the Timor Sea as the Indo-Pacific Through Flow (ITF). The ITF brings species and drifting eggs and larvae from the Pacific that populate habitats around the islands.

During winter and spring, strengthening south-east trade winds drive the nutrient-poor ITF into the NE Indian Ocean, where it encounters the Equatorial Counter-current (locally the South Java Current) entering from the west. The interaction of the two currents produce eddies that draw cooler, nutrient-rich water from the depths of the Java Trench. In the summer and autumn months, the SEC loses strength and retreats south, as the NW monsoon winds drive warmer, nutrient-poor waters back into the region and suppresses the upwelling.

The spring upwelling promotes phytoplankton plumes that spread far off the Java coast towards Christmas Island and, to a lesser extent, the Cocos (Keeling) atolls further west. Biological productivity, and the distribution of pelagic fish, are also influenced by strong mid-ocean currents that swirl around the shallow seamounts, spawning chaotic eddies and localised upwellings of nutrient-rich waters towards the sunlit surface.


Lying 10 and 12 degrees south of the equator respectively, Christmas Island and the Cocos (Keeling) Islands share a tropical monsoon climate which delivers consistently warm temperatures of 22–30 degrees and average annual rainfall of 2000mm. The high humidity (70–90 per cent) is tempered by south-east trade winds that blow for most of the year and are strongest between May to September (the SE Monsoon). There are two distinct seasons: a dry season from May–October, and a wet season between November–April (the NW Monsoon) that carries a potential for cyclones. At the northern edge of the cyclone belt, Christmas Island has never had a direct hit but has suffered damage from severe winds and heavy swells. However, cyclones are a major threat to the Cocos (Keeling) Islands, with 30 passing within 100km of them since 1961.


Christmas Island is the peak of a submarine mountain, a volcanic seamount that erupted from the ocean floor about 60 million years ago. It is roughly T-shaped, about 19km long and 14km wide, with a total area 135sqkm.

The coastline is an almost continuous limestone cliff reaching heights up to 20m, punctuated by caves carved by wave action. At several places the cliff line is broken by shallow bays that shelter beaches of sand or crushed coral. The largest of these is Flying Fish Cove which contains the island’s port and main settlement. The island is fringed by a coral reef across a narrow coastal shelf that plummets to the ocean floor at more than 5000m.

The sea cliffs rise steeply to a central plateau by a number of terraces, each marking a separate stage of tectonic uplift and erosion by the ocean. While the seamount core is basalt, most of the surface rock is limestone accumulated from coral growth over millions of years. The island’s highest point is Murray Hill (361m). The dominant vegetation is tropical rainforest, more than 60 per cent of which is national parkland.

Indian Ocean swells make big surf on the island reefs


The Cocos (Keeling) Islands comprise two atolls — North Keeling and the South Keeling Island group — collectively embracing 27 islands composed of coral sand and limestone. The islands have a total area of 14sq km and rise between 5m and 8m above sea level respectively. North and South Keeling lie 15km apart and are linked by a submarine plateau at a depth of about 1000m.

North Keeling is a single, nearly closed ring atoll measuring about 1sq km, with a small opening about 50m wide on the east side. Its shore rises steeply from a narrow fringing reef and slopes gently down to an interior lagoon. The whole island and the marine area extending 1.5km into the surrounding waters form the Pulu Keeling National Park, declared in 1995, and is accessible by permit only. The Park supports an internationally significant seabird rookery and is home to the only surviving population of the endemic, and endangered, Cocos Buff-banded Rail.

The South Keeling group incorporates five main islands — West, Horsburg, Direction, Home and South — and numerous small islets almost connected by coral reefs into an incomplete ring of about 26km circumference. At the northern end, Horsburgh Island is separated from the atoll by broad channels on either side about 14m deep. The reefs formed between 4000 and 7000 years ago. Three of the larger islands have freshwater ‘lenses’, underground accumulations of rainwater lying above seawater, that are accessed through shallow bores or wells.