Friday, 1 April 2016

Assessing the impact of land reclamation in the Spratly Islands.

The Spratly Islands are a widely distibuted archipelago of over 750 coral reefs, atols and islands in the South China Sea. Ownership of the islands is disputed between surrounding nations, with China, Taiwan, Thailand, Vietnam, Malaysia, the Philippines and Brunei all claiming part or all of the archipelago, and all of these nations except Brunei maintaining some sort of military presence in the islands. This competition has led to pressure to develop the islands, with nations attempting to establish permanent structures on even very small islands, which in turn has led to ambitious land reclamation projects, with material being dredged from the surrounding reefs to create new land, expanding the building space available.

In a paper published in the journal PLoS Biology on 31 March 2016, Camilo Mora of the Department of Geography at the University of Hawaii at Manoa, Iain Caldwell of the Hawaii Institute of Marine Biology at the University of Hawaii at Manoa, Charles Birkeland of the Department of Biology at the University of Hawaii at Manoa and John McManus of the Department of Marine Biology and Ecology at the University of Miami examine the impact of seven land reclamation projects carried out by the Chinese government in the Spratly Islands.

Previous land reclamation projects on coral reefs are known to have had severe effects that have spread far beyond the area initially touched. For example the United States completely destroyed a 4.4 km² area of reef by dredging off Johnston Atoll in Hawaii in the 1960s, as part of a project to build an airport on the island. However the damage was not limited to the area dredged, but spread, eventually affecting 28 km² of reef. A similar dredging project off the coast of Hay Point in Queensland, Australia, in 2006 resulted in the loss of coral cover up to 6 km from the site of dredging.

Corals also take a long while to recover from such activities; a project in Kaneohe Bay, Hawaii, in 1939 removed approximately 29% of the reefs in the bay, with almost no recovery recorded after 30 years, while a land reclamation project at Castle Harbour in Bermuda in the 1940s resulted in coral loss on the surrounding reefs that showed little sign of recovery after 32 years, and which has been linked to the extinction of several Fish species.

The Spratly Islands are considered to be an area of high biodiversity, with smaller atolls acting as a series of stepping stones between other reefs in the region. The reefs are considered to be in better condition than many reefs in other parts of the world, with an average of 68% Coral cover, compared to less than 25% for many Pacific islands. A number of reefs in the area are known to have been badly affected by a combination of El Niño conditions and the use of explosives and cyanide in fishing in the 1990s. with the worst affected areas suffering a in Coral cover from over 80% to as little as 6%, though most of these areas seem to have recovered well, with cover of 30%-78% recorded on the same reefs in 2004-8.

Mora et al. examined satellite images taken in 2014-15 of seven atolls recently reclaimed by China in the Spratly Islands, Cuarteron Reef, Fiery Cross Reef, Gaven Reef, Hughes Reef, Johnson South Reef, Mischief Reef and Subi Reef, and compared them to older images of the same atolls.

Two images of Fiery Cross Reef before (left) and after (right) land reclamation. Asia Maritime Transparency Initiative/Center for Strategic and International Studies/Digital Globe in Mora et al. (2016).

The seven atols were found to have gained a total of ~10.7 km² of land (an increase of more than 75 times the original landmass), but to have lost ~11.6 km² of reef, with reef being lost both to land reclamation and to dredging projects designed to allow boat access to lagoons.

Mora et al. believe that this dredging is likely to degrade the reefs ecologically and denude them of structural complexity. The dredging disturbs the seafloor, so that runoff from the new land can generate clouds of suspended sediment, which can adversely affect living Corals far beyond the area initially dredged, both abrading and burying established Corals and preventing larvae from settling. This can lead to breakdown of the atoll's ability to withstand erosion by waves and storms, as in the absence of living Coral the reefs are unable to repair themselves, leading to the potential for the complete loss of the atols (including any new reclaimed land) following major events such as typhoons.

Mora et al. also note that this is not a problem exclusive to Chinese held areas of the Spratly Islands, with similar land reclamation projects having been carried out by Malaysia, the Philippines, Thailand and Vietnam, as well as by China in the Paracel Islands, also in the South China Sea (they make no comment on the ownership of the affected islands, which is disputed in most cases). 

Given the potentially damaging nature of development in the Spratly Islands, and the potential for conflict over the territory, Mora et al. strongly recommend the development of a multinational approach possibly by the development of a marine protected area managed along similar lines to the Antarctic protected area.

See also...

http://sciencythoughts.blogspot.co.uk/2013/03/the-vanishing-corals-of-pelorus-island.htmlThe vanishing Corals of Pelorus Island.   Corals on Australia's Great Barrier Reef, as in other parts of the world, are known to be in trouble, with declining Coral coverage, diebacks, bleaching events and replacement of Corals by Macroalgae (Seaweed) on much of the reef. Unfortunately, recording of Coral fitness on the reef in an organized way only began...
http://sciencythoughts.blogspot.co.uk/2012/11/building-artificial-coral-reef-on-pulau.htmlBuilding an artificial Coral Reef on Pulau Weh, Indonesia.                                          Coral reefs are important marine ecosystems and vital economic resources to coastal communities across the tropics. However Corals in almost all areas have been dying back, due to pollution, rising sea temperatures, increased tropical cyclones and invasive species, such as the Crown of Thorns Starfish. This has led to...
http://sciencythoughts.blogspot.co.uk/2012/11/coral-decline-on-great-barrier-reef.htmlCoral decline on the Great Barrier Reef.   Coral Reefs are generally considered to be among the most important of marine ecosystems, providing protection to storm battered tropical shores and forming biological hotspots. However in the late twentieth and early twenty first centuries reef ecosystems have undergone a decline around much of the...
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