Tensions in the South China Sea increased last April when a Chinese coast guard ship sank a Vietnamese fishing boat near the Paracel Islands—a fiercely disputed territory in the South China Sea. Disputes over island territories in the region have endured for decades, with China, Vietnam, the Philippines, Taiwan, Indonesia, Malaysia, and Brunei all making overlapping territorial claims. The region is rich in natural resources and biodiversity, holding vast fish stocks and an estimated 11 billion barrels of oil and 190 cubic feet of natural gas.

The increased strain in Vietnam and China’s relationship was evident even before the April incident. In recent years, China has pressured Vietnam out of oil and gas exploration, implemented fishing bans in disputed waters near Vietnam and the Paracel Islands, and increased its military presence in the Paracel and Spratly Islands—another disputed archipelago strategically located along major shipping routes and rich in resources.

China’s claims in the region extend into the Exclusive Economic Zone (EEZ) of Vietnam. EEZs are 200-mile buffer zones off the coast of sovereign nations established by the 1982 UN Convention on the Law of the Sea within which countries have some exclusive rights over resources. This has sparked greater conflict between the two countries over resource utilization, with Vietnam working to strike a balance between asserting its territorial claims and maintaining a cooperative relationship with the Chinese government, with which Vietnam shares political and economic ties. In late 2019, for the first time, Vietnam threatened to bring legal action against China over disputes in the South China Sea. And just last month, Vietnam raised concerns over security in the region at the ASEAN Regional Forum.

Biodiversity Loss in the South China Sea

The strained relationship between China and Vietnam has not been the only consequence of the conflict. Increased military activity and commercial fishing in the South China Sea have taken a heavy toll on the region’s biodiversity.

The South China Sea is a global hotspot for biodiversity, home to important marine ecosystems, mangrove forests, and thousands of fish and sponge species. In fact, scientists believe the region holds “some of the highest marine biodiversity on earth, with 571 known species of coral reef alone.”

A key strategy of territory claimants has been to build islands in order to increase military presence in the region. Among the various countries involved in the conflict, China has been the most aggressive in building islands and is responsible for the majority of environmental damages caused by such projects. In total, China has built an estimated 3,200 acres of artificial islands, most of which are located in the Spratly Islands archipelago.

The dredging process involved in building these artificial islands has significant environmental consequences. Dredging breaks up coral reefs, disturbs ecosystems by changing wave patterns, and disrupts the migration corridor of many species through the South China Sea, including tuna. Sand plumes from dredging can also kill coral reefs by blocking sunlight or burying them.

Aside from creating manmade islands, Vietnam and China have also increased commercial fishing to strengthen territorial claims. China has expanded its fishing practices in the Spratly and Paracel Islands in order to bolster historical claims to the territories, going so far as to pay fishermen to maintain presence in its Spratly outposts. The use of fishing vessels as political pawns has led to conflicts such as the sinking of the Vietnamese fishing boat earlier this year and the arrests of several Chinese fishermen for illegal fishing in Vietnam in 2001.

Overfishing in the South China Sea has caused fish stocks to decline by an estimated 70-95 percent since the 1950s. Despite overfishing problems, the artificial islands have provided an opportunity to expand fishing in the region into waters that were previously too difficult to access. Additionally, the dredging process used to build these islands is harming fish larvae populations along the coral reefs. The combination of increased commercial fishing in the South China Sea and the endangerment of fish larvae from dredging is putting the South China Sea’s fish stocks at great risk.

Fossil Fuels as Threat Multipliers

The presence of oil and gas reserves in the region has exacerbated the environmental and political consequences of the conflict. In July, Vietnam canceled an offshore oil and gas exploration project after ongoing pressure from China. This pressure is seen as part of a larger effort by China to block non-Chinese oil and gas development in the South China Sea—estimated to be worth $2.5 trillion.

Oil and gas resources in the region also increase the potential for environmental harm. Ecosystems in the South China Sea, already polluted by military activity and shipping, will be put at risk as the region’s oil and gas reserves are exploited. Increased shipping activity and potential oil and gas leaks also heighten the risk of pollution.

While China and Vietnam may have conflicting claims over island territories in the South China Sea, they also have a shared interest in sustaining the availability of natural resources in the region. However, with the pace of environmental degradation from the conflict, there will not be much left for either country unless they can find a way to cooperate.

[This article originally appeared on newsecuritybeat.org.]

Find out more about fishing disputes in the South China Sea from our ECC Factbook case.