South China Sea Ecosystem

Category: Marine and Oceanic Biomes.

Geographic Location: Asia.

Summary: Unparalleled biodiversity is the rule here, but there is a race on between fossil fuel extraction, international political tension, and those cooperating to restore, balance, and conserve the ecosystem.

Awash in the waters of the Indian and Pacific Oceans, the South China Sea contains up to one-third of the world’s marine biodiversity, which gives the region a substantial renewable resource base—but one that by some accounts is slowly crumbling. Sealed below its floor is an unusually large amount of crude oil and natural gas, which has sparked international conflict over extraction rights. Conservation and preservation of the sea’s unique and diverse ecosystems may prove to be the key that opens the way for cooperation among the people of the region.

Geology and Origins

The South China Basin is the deepest part of the sea in this region. It is surrounded by three significant geomorphologic features: a segment of Eurasia’s continental shelf in the west; the Reed Tablemount and Manila Trench to the east; and the Sunda Shelf to the south. Around 30 million years ago, a vast block of rock called the Reed Tablemount slowly separated from the Eurasian continent. In between, upwelling magma cooled and hardened to compose the basin floor, a process that ended 17 million years ago. The Spratly Islands sitting atop the Reed Tablemount are mostly uninhabited, but are the most politically contested archipelago in the world. In 2018, tensions regarding the islands increased further after China had a system of defensive missiles installed at some of its outposts on the islands.

To the east, this submarine plateau drops into the Manila Trench, an abysmal habitat where marine life remains mostly a mystery. As the Eurasian tectonic plate slowly moves below the Philippine plate, the upper layer of the Earth’s crust cracks and fissures, giving magma from below an opportunity to flow to the surface and create volcanic islands.

In the warm tropical and subtropical climates, corals colonize these mountains to form coral reefs. When the forces of erosion cause rock to disappear below the water’s surface, the remaining living rings of coral create an atoll surrounding a lagoon. The coral reefs and atolls stretching from the Philippines island of Palawan down to northern Borneo form the base of southeast Asia’s Coral Triangle, which consists of a network of protected areas that tapers toward Australia. Environments like these are mainsprings of marine biodiversity—and extremely rich hatcheries for both the Indian and Pacific Oceans.

Biodiversity

Much of the South China Sea’s biodiversity springs from the continental and Sunda shelves here, which, along with the Tablemount, endow it with general shallowness. Along the coastal rim, terrestrial biomes such as tropical rainforests and savannas interact with inland aquatic biomes such as the Mekong, Red, and Pearl rivers, with marine estuaries creating life zones bristling with myriad species of plants and animals.

Among the most animated transition zones along the coast of the South China Sea are mangrove forests, in which gentle warm-water sea currents bring salt to the mouths of freshwater rivers and streams. Such areas reproduce exceptionally high levels of biomass that in various ways become dynamic natural resources. Mangroves protect coastlines from erosion and the added destructive effects of recurrent typhoons, which usually form between May and September. The region supports about 30 species of mangrove, and has extensive swaths of seagrass beds in the intertidal zones around its perimeter—yet another rich area providing shelter, breeding and feeding grounds for myriad mollusk, crustacean, fish, and marine mammal species. However, progressively more such habitat is being lost to industrial pollution, agricultural runoff, coastal development, aquaculture, and overfishing. In 2015, a report released by the Paulson Institute, which worked alongside the Chinese government, found that the speed of the country's land reclamation in efforts to support economic development had led to the loss of 73 percent of its coastal mangroves, threatening the habitat of several migratory birds and decreasing the natural level of protection against rising seas.

The Sunda Shelf and Coral Triangle have some of the world’s most spectacular coral reefs, which teem with species of mollusks, crustaceans, sea snakes and turtles, but they, too, are succumbing to environmental threats. Reef raiding, blasting, and poisoning have depleted these creatures; subsistence and commercial fishers compete for depleted fish stocks, while demand for seafood is at an all-time high. The seagrass and soft bottom beds suffer similar damage, as trawling ships scrub the floor of all that can and cannot be eaten by human beings. International bodies have made some headway in outlawing such practices and introducing more sustainable fishing regimes, but the struggle is by no means won.

Human Factors

The territories of Brunei, Cambodia, China, Indonesia, Malaysia, Philippines, Thailand, and Vietnam extend into the South China Sea. Approximately 270 million people live in or near the coast of the South China Sea, a population expected to double by 2040. The economies of most of these countries depend heavily on international trade in manufactured and agricultural goods. Because shipping is the least expensive form of transport, the sea is central to intraregional trade.

Further, it is also one of the world’s major global shipping lanes, because its waters funnel through the Straits of Malacca, which for hundreds of years has been a significant passageway for people and goods traveling east and west. With the opening of the Suez Canal in 1869, and the more recent rise of China and Japan as first-rate economies, the interaction among Europe, southwest Asia, and Africa with the countries of the South China Sea has never been greater.

Climate change has impacted fishing in the area, causing some species to move north to cooler waters. As the temperatures of the waters change, and species of fish continue to relocate, the nations that rely upon commercial fishing in the South China Sea may become increasingly protective of their areas, vying for whatever fish remain. Not only can climate change impact the marine life living in the South China Sea, but it also may have social and political impacts upon the area, depending on the physical outcomes upon the natural systems here.

Beyond warming waters, increasing acidification has had an effect in the region. Corals are stressed and in some cases have died off. Other reefs are heavily damaged by Chinese scraping the sea bottom with trawlers looking for fish. Many fish rely on these reefs for food and protecting.

To stanch these threats, the United Nations Environment Programme (UNEP) and the Global Environment Facility, along with seven regional nations, have been involved in the South China Sea Project since 2006. Comprehensive scientific surveys on several transboundary ecosystems and subsystems have been completed; these will provide a baseline from which to gauge future changes to this large marine ecosystem.

National governments along with a consortium of international universities are working together to give local people the skills to survey and manage ecosystems; promote public awareness of environmental issues; and understand legal and regulatory issues concerning restoration, preservation, and conservation of local, transboundary environments.

The hope is that increasing cooperation among the people of the South China Sea will lead to sustainable development policies and practices, so that certain geopolitical tensions will no longer threaten to snap the string of cultural and natural pearls adorning the sea. However, such tensions have prevailed into the 2020s, leading to concerns regarding overfishing and increasingly depleted fish stocks as fisheries in countries in the region face greater competition without any real regulation of practices. The Chinese government rejected a 2016 decision by a Hague tribunal stating that its claims of historic rights to much of the territory in the South China Sea were not legal.

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