Increasing occurrences of hypoxia, or low levels of oxygen in a body of water, are threatening coral in tropical environments, a research paper that a Taiwanese research team contributed to said.
The paper, titled “Increasing hypoxia on global coral reefs under ocean warming,” was published on Thursday on the online journal Nature Climate Change, detailing the results of a study led by the Scripps Institution of Oceanography at the University of California, San Diego.
Chou Wen-chen (周文臣), a professor at National Taiwan Ocean University’ Institute of Marine Environment and Ecology who contributed to the paper, on Saturday said that in the past, hypoxia mostly occurred in temperate seas, but the phenomenon is now being observed in tropical waters.
Photo courtesy of Su Huai
Chou’s team found that five coral reef ecosystems near Taiwan’s Pratas Islands (Dongsha Islands, 東沙群島) and Itu Aba Island (Taiping Island, 太平島) are all in a state of moderate to severe hypoxia.
Teams from Taiwan, Japan, Panama, Puerto Rico and the US studied 32 coral reefs in 12 locations worldwide, observing day-night changes in oxygen levels in the seawater.
“The study clearly reveals that global warming not only aggravates the bleaching of corals and the acidification of oceans due to the increase in dissolved carbon dioxide, but also worsens hypoxia,” Chou said.
The teams used the four climate change scenario models proposed by the UN Intergovernmental Panel on Climate Change (IPCC) to predict how dissolved oxygen levels change due to climate change, he said.
The study showed that by the year 2100, the temperature rise would cause oxygen solubility to decrease, and the oxygen consumption rate of coral’s biological metabolism to increase, which would greatly worsen hypoxia in coral reef ecosystems, Chou said.
However, Huang Wei-jen (黃蔚人), an associate professor at National Sun Yat-sen University’s College of Marine Sciences, said that hypoxia cannot be explained by one factor.
“It is necessary to understand the relationship between hypoxia and other factors, such as rising sea temperatures, accelerated respiration and coastal eutrophication,” he said.
Scientists are looking at ways to stave off bleaching by studying high-temperature-resistant corals, but this would not solve the problem of hypoxia, said Chen Chao-lun (陳昭倫), an associate researcher at Academia Sinica’s Biodiversity Research Center.
“A comprehensive study of what causes bleaching is needed to deal with future changes,” Chen said, adding that the research published on Thursday was the first to study coral reefs in different seas simultaneously, and to confirm hypoxia on a global scale.
The study found that more than 97 percent of the sampling points were in varying degrees of hypoxia, of which 13 percent were severely hypoxic, he said, adding that the points measured near the Pratas Islands and Itu Aba were among the most severely hypoxic samples.
“Under the scenario of extremely high emissions estimated by the IPCC, the number of coral reefs in environments with very low oxygen levels will nearly triple by the end of this century,” Chen said.
Most research focuses on hypoxia in temperate climates, and for organisms that dwell on the ocean floor, he said.
“Also, this study looks at the impact of hypoxia on individual organisms. Whether climate change or increased carbon dioxide emissions increase the impact of hypoxia on the overall coral reef ecosystem requires more research,” he said.
The ocean absorbs a large amount of heat produced by global warming, and dissolves a large amount of carbon dioxide, increasing the possibility of algal blooms, which increase the occurrence of hypoxia in coral reefs, he said.
It is also necessary to avoid polluting the habitats of marine organisms, which could worsen hypoxia through eutrophication, National Museum of Marine Biology and Aquarium researcher Tang Chuan-ho (唐川禾) said.
DEFENDING DEMOCRACY: Taiwan shares the same values as those that fought in WWII, and nations must unite to halt the expansion of a new authoritarian bloc, Lai said The government yesterday held a commemoration ceremony for Victory in Europe (V-E) Day, joining the rest of the world for the first time to mark the anniversary of the end of World War II in Europe. Taiwan honoring V-E Day signifies “our growing connections with the international community,” President William Lai (賴清德) said at a reception in Taipei on the 80th anniversary of V-E Day. One of the major lessons of World War II is that “authoritarianism and aggression lead only to slaughter, tragedy and greater inequality,” Lai said. Even more importantly, the war also taught people that “those who cherish peace cannot
STEADFAST FRIEND: The bills encourage increased Taiwan-US engagement and address China’s distortion of UN Resolution 2758 to isolate Taiwan internationally The Presidential Office yesterday thanked the US House of Representatives for unanimously passing two Taiwan-related bills highlighting its solid support for Taiwan’s democracy and global participation, and for deepening bilateral relations. One of the bills, the Taiwan Assurance Implementation Act, requires the US Department of State to periodically review its guidelines for engagement with Taiwan, and report to the US Congress on the guidelines and plans to lift self-imposed limitations on US-Taiwan engagement. The other bill is the Taiwan International Solidarity Act, which clarifies that UN Resolution 2758 does not address the issue of the representation of Taiwan or its people in
Taiwanese Olympic badminton men’s doubles gold medalist Wang Chi-lin (王齊麟) and his new partner, Chiu Hsiang-chieh (邱相榤), clinched the men’s doubles title at the Yonex Taipei Open yesterday, becoming the second Taiwanese team to win a title in the tournament. Ranked 19th in the world, the Taiwanese duo defeated Kang Min-hyuk and Ki Dong-ju of South Korea 21-18, 21-15 in a pulsating 43-minute final to clinch their first doubles title after teaming up last year. Wang, the men’s doubles gold medalist at the 2020 and 2024 Olympics, partnered with Chiu in August last year after the retirement of his teammate Lee Yang
The Philippines yesterday criticized a “high-risk” maneuver by a Chinese vessel near the disputed Scarborough Shoal (Huangyan Island, 黃岩島) in a rare incident involving warships from the two navies. The Scarborough Shoal — a triangular chain of reefs and rocks in the contested South China Sea — has been a flash point between the countries since China seized it from the Philippines in 2012. Taiwan also claims the shoal. Monday’s encounter took place approximately 11.8 nautical miles (22km) southeast” of the Scarborough Shoal, the Philippine military said, during ongoing US-Philippine military exercises that Beijing has criticized as destabilizing. “The Chinese frigate BN 554 was