As rising sea temperatures and human activities threaten biodiverse aquatic ecosystems, safeguarding Taiwan’s coral reefs becomes paramount to ensuring environmental resilience. 

Surrounded by water as far as the eye can see, Taiwan has oceanic views as breathtaking below the surface as they are above – or at least they used to be. Once known as the “coral kingdom,” Taiwan is now grappling with a coral crisis.  

The waters around the island face a two-fold challenge. On the one hand, they are threatened by human-induced climate change, impacting the marine ecosystem and the island’s coastlines. On the other hand, they play a crucial role in Taiwan’s efforts to combat climate change, particularly through the development of offshore wind energy. 

Despite notable progress in renewable energy projects, the ocean that sustained the island’s earliest human inhabitants may not be a reliable source of food in the future. What’s more, within decades rising sea levels could threaten parts of the lowlands – especially those where over-extraction of groundwater has caused the land to subside.  

Taiwan’s rapid industrialization and urbanization have had a noticeable and detrimental impact on the marine environment, says Liu Shao-lun, a professor of life sciences at Tunghai University in Taichung. Although coral reefs cover only a tiny fraction of the seabed, around 0.2%, they host at least 25% of all marine life forms. According to some estimates, they are the source of 10% of fish caught worldwide. “Over 50% of our coast has already been built on, and yet more construction is planned,” says Liu, who specializes in marine plant and community ecology.  

Liu highlights the visible consequences of development near his hometown in Hengchun, Pingtung County. He recalls how seagrass ecosystems, which function as natural carbon sinks (anything that absorbs more carbon from the atmosphere than it releases), once thrived in the tidal pools at Wanlitong, a top scuba diving destination within Kenting National Park. Nowadays, due to the construction of a beach resort and the uncontrolled wastewater discharge from nearby households and homestays, much of the seagrass has disappeared. Liu says he has no doubts that tourism has also harmed marine ecosystems near Xiaoliuqiu and Green Island, both well-known destinations. 

One impact of climate change on the ocean can be seen in the inverse relationship between water temperature and the amount of dissolved oxygen in the sea. As an example, Liu points to Dongsha Atoll, a Taiwan-controlled outpost 414 km southwest of Kaohsiung, where he conducted research between 2015 and 2017. “We saw a massive die-out of invertebrates, probably because of lower oxygen levels,” he says.  

While coral reefs are not net absorbers of carbon dioxide, they help preserve lagoons, mangrove forests, and other carbon sinks. By absorbing much of the energy within waves, they also provide coastal areas with some protection against storm surges and reduce the rate of land erosion.  

Corals exist in a symbiotic relationship with small algae known as zooxanthellae, which supply oxygen and nutrients to the corals while processing their waste. But when corals experience heat stress or pollution, they expel the zooxanthellae. The corals then lose their color, a phenomenon known as “bleaching.” 

The algae will return if the heatwave is brief, or the pollution dissipates quickly. If not, the corals will soon die. According to some forecasts, global warming of just 1.5 degrees Celsius could destroy between 70% and 90% of the world’s reefs. 

Liu says that while conducting his research, he noticed that the inner reef at Dongsha Atoll had been severely degraded and that the more heat-tolerant macroalgae (seaweed) were thriving. He explains that when seaweed becomes dominant, the entire ecosystem shifts, homologizing other species’ food resources and consequently impacting fisheries.  

For the time being, the outer reef at Dongsha Atoll is in decent shape, likely benefiting from exposure to the cooler waters of the ocean depths. But last year saw record-high surface temperatures, and Liu predicts that “every year for the next decade will be the hottest on record.” 

Seaweed dominance has already had a detrimental effect on some areas. Last summer, excessive seaweed growth damaged oyster beds off the coast of Changhua County. According to a June CNA report, farmed oysters in the county’s Fangyuan Township experienced a mortality rate of between 40% and 50%.  

This over-blooming event was likely triggered by an abundance of nutrients in coastal waters, much of which can be traced to livestock and poultry farms. Liu explains that improperly managed manure sludge often gets washed away into the ocean by the plum rains, which typically start around the end of April. As global temperatures rise, such blooms are likely to become more frequent and start earlier in the year, he adds. 

Many common seaweed species found along Taiwan’s coasts thrive in spring and then vanish by summer. But Liu worries that warmer conditions could lead to the dominance of non-seasonal macroalgae, which would outcompete corals for light and space.  

Some propose cultivating seaweed as a way to sequester carbon in much the same way that woodlands can absorb atmospheric carbon dioxide (see “Could Seaweed Become Taiwan’s Climate Game Changer?” in the February 2024 issue of Taiwan Business TOPICS). Liu is unconvinced. He points out that nutrient concentrations decline with distance from the shoreline. “Seasonality is another factor,” he says. “There are a lot of things we’ll need to think about.” 

In the past two years, coral reefs in northern Taiwan have started showing signs of bleaching, something researchers had expected would not occur until sometime between 2030 and 2040. “We didn’t think we’d see this so soon,” says Liu. “It’s worse than scientists predicted. We don’t know when the tipping point will come and cause a massive ecological shift.”  

Elsewhere, the news is equally grim. A 2012 academic paper describes Wanlitong’s “degraded coral community,” predicting that macroalgae will eventually dominate the area. The researchers attribute the shift to nutrients released from human waste and the depletion of herbivorous fish populations, a consequence of decades of overfishing. Research published in 2020 warns that corals living close to Maanshan Nuclear Power Plant in Pingtung County may “already live at the ceiling of thermal tolerance” and that future climate change trends might be untenable for the corals.  

Restoration efforts 

A number of organizations are responding to reef decay by cultivating corals. For example, Taiwan’s Delta Electronics Foundation is leveraging its parent company Delta Electronics’ technological strengths by using LED lighting to accelerate the growth of its farmed corals. The foundation’s volunteers then transplant the corals to Keelung’s Wanghaixiang Chaojing Bay Resource Conservation Area, where they also remove unwanted algae and monitor the corals’ health. 

Danish multinational Ørsted is also committed to reducing its environmental impact. In addition to focusing on minimizing the negative effect of wind turbines and other infrastructure, the company is investing in coral restoration projects to develop, test, and refine a toolbox of scalable and effective measures, says Lee Chih-an, Ørsted’s Asia-Pacific Senior Sustainability Advisor.  

Ørsted has four offshore wind projects either in operation or under construction in Taiwan, with three more under development. At two of these sites, Ørsted’s ReCoral project is actively working to establish artificial coral reefs.  

The selected sites, located off Taiwan’s west coast, offer relatively stable temperatures of around 20 to 25 degrees Celsius. Lee notes that these temperatures are ideal for corals struggling to adapt to rising sea temperatures. However, the sites also present challenges. Their distance of 35 and 60 km from the coast makes it more difficult to plant and monitor the corals.  

Ørsted’s goal is for all its renewable energy projects commissioned from 2030 onward to have a “net-positive biodiversity impact,” Lee says. She clarifies that the ReCoral project does not receive any subsidies from the Taiwan government. 

Since 2021, the ReCoral team has partnered with the Penghu Fisheries Research Center, part of the Ministry of Agriculture’s Fisheries Research Institute, to collect coral eggs washed onto the shores of the Penghu islands. By spring 2022, the team had collected around 200,000 “surplus” eggs that would otherwise go to waste (nothing is being removed from existing coral ecosystems). Around 10,000 cultivated coral larvae were released into mesh cages attached to turbine foundations later that summer.  

Last year, the method was refined. “We let coral larvae first seed on brick tiles in the Penghu lab, so they’d grow there and become stronger before release, increasing their chances of adapting to the offshore environment,” Lee says. Of the 111 turbines that comprise the Greater Changhua wind projects, four are being used for ReCoral trials. “This project is at a proof-of-concept stage for us to verify under what conditions offshore wind farms in tropical or subtropical waters could potentially become coral habitats,” says Lee. “Corals grow very slowly, and it’s still too early to get accurate data on growth at this location.” If and when the project is expanded will depend on the trial’s results, which are being shared with the broader research community, she adds.  

Tunghai University’s Liu says that in the same way sinking old ships has proven to be an effective way of creating habitats for reef-building corals, efforts to create coral reefs beneath wind turbines may also succeed. However, he cautions that these efforts might face scalability challenges.  

Extending the life of physical infrastructure is often more sustainable than replacing it. In Taiwan, wind farms are granted 20-year licenses and must obtain additional permits to continue operating thereafter. Anticipating that its turbines will generate clean electricity for an extended period, Ørsted “is working closely with suppliers on improving component endurance and repairability, as well as material circularity of those that become obsolete,” says Lee.  

As for new infrastructure projects, Liu suggests that the authorities prioritize locations where the shoreline is already encased in concrete. “We shouldn’t sacrifice our natural coastline,” he notes. “It doesn’t make any sense to me. We’ve already pushed ourselves to the limit.”   

Liu was among those who campaigned against the Guantang Liquefied Natural Gas Terminal, which is now under construction at Datan in Taoyuan. Environmentalists argue that the terminal will endanger an ancient and ecologically important coralline algal reef. Supporters of the project – which Taiwanese voters narrowly endorsed in a December 2021 referendum – say that revisions to the plan will minimize its impact on the seabed. In his campaign, Liu proposed that the terminal should instead be built at the Port of Taipei. 

The consequences of climate change and rising sea levels along Taiwan’s coasts have already begun to manifest. At the end of August last year, low atmospheric pressures caused by Typhoon Sulla resulted in exceptionally high tides, causing seawater to intrude parts of Kaohsiung’s Qijin District for three consecutive days despite the absence of rain. Elsewhere in the city, near Sanmin Market and the Love River, residents had to contend with calf-deep water. Flooding was also reported in Tainan’s Anping, Jiangjun, and Beimen districts. 

On the same day, the Chinese-language Liberty Times reported that the central government had committed NT$91 million to install extra water pumps in Qijin and raise the height of the district’s embankment from 1.1 meters to at least 1.5 meters.  

Since the early 1990s, Kaohsiung has experienced a sea level rise of approximately 11 cm, with the ocean currently ascending at a rate of 0.36 cm per year. In places like Keelung, the sea is rising even faster. 

In Hualien County’s coastal Fengbin Township, the problem is not so much inundation as erosion. Apart from natural factors, soil erosion is caused by irresponsible farm management or deforestation for urban area expansion, tourism development, and road construction. Over a decade ago, a survey on 283 plots revealed that nearly 40% of the land area, totaling 45.7 hectares, had eroded into the ocean. It’s unclear how much of this erosion was caused by human activity, but that is no consolation to the Indigenous families losing ancestral lands.