Vianney Denis is a researcher at the Institute of Oceanography at National Taiwan University in Taipei, Taiwan. His work focuses mainly on coral reefs, ecological physiology and marine community dynamics. Internationally recognised, with over 1,900 citations of his work, he combines scientific expertise with a practical approach to marine ecosystems to understand and model the interactions between the ocean, climate and biodiversity.

The following interview explores his thoughts on ocean modelling, climate prediction, and the creation of interactive platforms for global ocean research and data governance.

A cross-disciplinary look at coral ecology in Taiwan

A marine ecology researcher and associate professor at National Taiwan University, he has been living in the country for nearly twelve years and has been running his own laboratory since 2015. His career first took him to Academia Sinica, ‘a bit like the Taiwanese CNRS’, where he completed a post-doctorate before devoting himself to his current research.

His field of study is broad: he defines himself as a marine ecologist working mainly on coral reefs, but his research ranges from coral physiology at the organism level to studies of fish and coral communities at the ecosystem level. ‘I haven’t chosen between a physiological or ecological approach; I try to link the two.’

The value of a dual scale of observation

For him, understanding ecosystem responses requires focusing on individuals. ‘You can look at changes in ecosystems, but if you don’t understand how a species responds, it’s hard to really understand what’s going on.’ This approach involves linking field observations and molecular data: « What interests me is trying to link the two. « 

What makes his method unique is that his experiments are conducted directly in the field, not in an aquarium. Although his laboratory is located in the heart of Taipei, his work regularly takes him into the field, particularly to Green Island and Kenting, for campaigns lasting several days.

Taiwan, a unique natural laboratory

According to him, Taiwan’s appeal lies in the exceptional diversity of its marine environments: ‘Around Taiwan, we have three very different environmental units: the South China Sea Province, the Kuroshio and the East China Sea Province.’ This rare juxtaposition allows us to observe very contrasting ecosystems within a small area.

In the south, tropical reefs face regular bleaching episodes linked to summer temperature rises. In the north, which is subtropical, certain tropical species are beginning to appear: « Decline on one side, expansion on the other. These trends give rise to two research hypotheses: the latitudinal expansion of tropical species and the ‘deep refuge hypothesis,’ the idea that mesophotic reefs, located between 30 and 100 metres deep, could serve as refuges from warming.

Depth as a refuge?

The concept of mesophotic refuge zones attracted considerable interest between 2010 and 2015, but the results remain mixed: ‘We cannot generalise; some deep areas suffer from the same problems as shallower areas.’ The effects vary depending on the species, the sites and even the years. Fish seem to benefit more from this depth than corals, thanks to their ability to migrate vertically.

Adaptive capacity and intraspecific diversity

In the 2000s, there was a scientific consensus that corals, due to their long lifespan and late maturity, were unable to adapt to rapid warming. Recent research has qualified this view. Certain mechanisms, such as gradual thermal acclimatisation and pre-existing genetic diversity, offer hope: ‘If we lose 90% of a species but 10% of individuals survive, recolonisation can occur from that 10%.’

Climate change and local pressures

The impact of climate change on reefs varies from region to region. In Australia, massive bleaching events on the Great Barrier Reef have caused significant declines. In the Caribbean, the effects are exacerbated by pollution, disease and ecological imbalances.

In Taiwan, the situation is unique: ‘We have temperature anomalies, but also high cyclonic activity.’ Typhoons, by lowering the water temperature, can mitigate thermal stress and limit bleaching. ‘For corals, typhoons are not necessarily a bad thing; they can even create diversity by opening up ecological niches.’ The absence of typhoons in 2020-2021 coincided with significant bleaching, followed, however, by a good recovery.

Restoration, yes, but by tackling the real causes

For Vianney Denis, restoration efforts must first address the most immediate and localised threats. When it comes to coral reefs, he warns against the temptation to hide behind climate change as the sole cause. In Taiwan, he explains, ‘what will really damage the reefs is not climate change, it’s human impact.’

He cites pollution, domestic waste, soil erosion following unregulated coastal construction, and uncontrolled tourism development: ‘Before climate change can have an impact, there will be no more coral.’ ‘ On Green Island, so named for its green waters, he notes that ’now, along a whole stretch of the coast, it’s no longer green. »

The limits of marine protected areas

In this context, he is sceptical about the systematic use of marine protected areas (MPAs) as a conservation tool: ‘All you have to do is draw a circle on a map and it becomes an MPA.’ In his view, these measures can be useful, but only if they are accompanied by concrete measures to address the terrestrial causes of degradation. However, ‘many of the problems are not marine, they come from the land.’

He therefore believes that the international policy of creating 30% MPAs by 2030 is largely disconnected from the reality on the ground. ‘We’re not putting money into protecting our marine areas in our territorial waters, but we’re investing in areas that don’t belong to us.’

Natural solutions and extreme interventions

He advocates nature-based solutions, such as restoring mangroves and other ecosystems capable of trapping sediments before they reach the reefs. At the other extreme, he mentions technological interventions such as genetically modified corals or the selective breeding of more resistant corals. However, these approaches are ‘very local’ and ‘not replicable on a large scale’.

Redistribution of corals and socio-economic impacts

While some corals may move to new, more favourable areas, this redistribution will have major consequences: ‘Equatorial and tropical regions, such as Indonesia and the Philippines, will lose some of their fishery resources, with direct impacts on coastal communities.’

The example of Liuqiu Island

Liuqiu, southwest of Taiwan, has become famous for its sea turtles, which can even be seen from the surface. But this unusual abundance raises questions. Current surveys show ‘7% coral cover’, compared to nearly 50% in the 1970s.

The habitat is now dominated by algae, which is good for turtles but reflects a profound ecological imbalance.

The likely causes are summer tourist overload, pollution, sedimentation, and perhaps the influence of waste from Kaohsiung and the Gaoping River. ‘Creating a marine reserve here would not change anything if the problem is pollution.’

A policy that is too timid

He deplores the lack of ambitious action on the part of the authorities: ‘We plant corals, we count turtles and dolphins, we educate people, but nothing addresses the underlying problems.’ Economic interests, particularly those linked to heavy industry and offshore wind farm projects, take precedence over conservation.

The situation goes beyond Taiwan: ‘It’s hard to be optimistic when you see the political responses. The policy as a whole is disastrous. Major international initiatives, such as the United Nations and marine protected areas, are not tackling the root causes.’

Vianney highlights how certain international decisions, such as the approval of new marine protected areas on the high seas, are disconnected from the real emergencies.

Between assumed pessimism and rejection of political correctness

Faced with this inertia, he advocates a direct approach, even if it means shocking people: ‘I am not at all politically correct.’ During a recent official presentation, he did not hesitate to denounce the lack of vision and the accumulation of symbolic measures. ‘My title will be Taiwan Conservation: Many Challenges, No Vision.’

He describes his pessimism as a strategic choice: ‘Some people think we should remain optimistic, but I accept that I am pessimistic, without complaining.’

Ecological research: defending rather than discovering

He emphasises the specific nature of environmental science: In his view, evaluation criteria remain modelled on the fundamental sciences, even though the purpose is different.

He regrets that many researchers, out of weariness or self-interest, end up straying from their initial convictions. He also points to a troubling disconnect: ‘You can spend the day studying parrotfish and then eat them for dinner at a restaurant.’

Data opacity and controversial funding

Research data should be accessible, but he notes that it is often published in aggregate form, preventing reuse. This culture of retention is compounded by a growing dependence on private funding, which is sometimes highly controversial.

He cites the Saudi-funded Cordap programme, which attracts many researchers due to a lack of alternatives. ‘I have a very big problem with the idea of accepting funding of this kind.’ Large foundations, linked to the oil industry or states with a questionable human rights record, are now investing heavily in marine research, thereby legitimising their image.

His position in Taiwan allows him to benefit from a generous annual public budget of €30,000 to €40,000, which provides a solid operating base and allows him to avoid resorting to such funding as much as possible. But he notes that ‘90% of people turn a blind eye’ to the origin of the funds, preferring to protect their careers and projects.

The conclusion is clear: ‘The world of research is sick, and the world in general… what a world!’