Coral adaptation to climate change

© A. Amiel - Kahikai - Tara Expeditions Foundation

Vianney Denis is a French scientist who has been living in Taiwan for 8 years and teaches at the National Taiwan University, in the capital Taipei. His laboratory, the Functional Reef Ecology (FRE) Lab, offers the opportunity to combine his 2 passions, diving and studying the diverse coral, which thrives in Taiwan. We interviewed with this assistant professor who studies the ecological responses of coral to climate change in marginal environments.

 

You’re interested in coral functionality. What does that mean?

We are trying to identify how organisms function and their roles in the ecosystems. We now know that each species responds differently to disruptions and stress. My work is to define the various strategies that corals have developed to survive environmental stress factors. For example, often after a severe coral bleaching event, only the most resilient species survive. On a larger scale, this work will help us understand changes in the ecosystem and identify which coral species will populate reefs in the future.

How do you study coral under stress?

I study about 10 common species around Taiwan, selected in different habitats. They can be in deep water (down to 60 meters), or in regions located at higher latitudes like, for example, in the north of Taiwan. In this area, when the tide goes out during summer, some species colonize tide pools where seawater temperature can reach 37ºC. Taiwan provides me with a natural laboratory for my studies. I assess the physiological changes occurring which enable coral to colonize these various habitats, such as changes affecting their zooxanthellae, proteins, skeleton density, etc. By analyzing and combining these characteristics, I identify their functions (performance) in the ecosystem. I take particular account of their diet. Under normal conditions, coral mainly feeds on what their symbiotic algae produce, and to a lesser extent, on plankton. When coral bleaching events occur, we observed that some species manage to change this regime. This suggests that certain corals might be able to adapt their diets according to environmental conditions.

 

Vianney_Denis_echantillonnage@Noemie_Olive
Vianney Denis sampling coral onboard Tara on Green Island site – © Noémie Olive / Tara Expeditions Foundation

 

Is Taiwan a good place to study coral?

What I appreciate in Taiwan is the presence of contrasting environments on a relatively small scale. There are beautiful and diverse reefs to the southeast of Taiwan, with more than 300 coral species. They benefit from the warm waters of the Kuroshio, a strong current. The north of Taiwan is not under its influence, and water temperature in winter prevents the development of coral reefs. Due to global warming, some species could migrate north to new areas, thus modifying their distribution. The consequences of this potential tropicalization are not yet well known in Taiwan, but we are very closely monitoring the situation.

 

What is your ultimate goal in studying coral?

My goal is to demonstrate the importance of coral in the ecosystem, to better preserve them. In Taiwan, each place is different. The north, the south, shallow reefs or deeper ones: each area is specific! To preserve this diversity, no area must be neglected, and we must now think on a global scale about managing the region’s coral reefs.
 

Noémie Olive

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