Tara welcomes aboard Francesca Benzoni, a long-standing collaborator. She is an IRD* researcher, biologist and coral specialist, and coordinated the first study of coral during Tara Oceans 2009-2013, an expedition primarily dedicated to plankton. In 2010, while working at the University of Milano-Bicocca, she led 4 specific missions focused on coral in Djibouti, Saint Brandon, Mayotte and the Gambier Archipelago. Now with the IRD Entrecasteaux-NC 2017** project, Francesca goes over the coral studies conducted aboard the schooner from Tara Oceans to Tara Pacific. A scientific perspective adapted to profound ongoing environmental changes.
Francesca Benzoni and Serge Planes answer the questions during the projection of the film “Tara l’odyssée du corail” in Noumea. © Vincent Hilaire – Tara Expeditions Foundation
Francesca, can you tell us about the scope of work carried out on these 4 missions dedicated to coral and included in the Tara Oceans expedition?
“From January 2010 to June 2011, during the Tara Oceans expedition, we worked for 61 days on 4 different sites. We carried out 101 dives and collected 2,500 samples of coral, zooxanthellae and sea water. We also performed the first core samplings on Porites.
Thanks to all this work, we created a baseline for these 4 selected sites and collected as many samples of coral and zooxanthellae as possible. The study of bacterial biodiversity started there, as well as Tara’s collaboration with the Scientific Center of Monaco (CSM). We wanted to research the same coral species and the related bacteria in the framework of the Tara Oceans expedition, but didn’t always find them.
In this sense, Tara Oceans was the precursor of Tara’s current research, implementing the protocols in use today. Eighteen scientific papers have already been published in connection with these missions and we’re still studying the resources collected during these years. The material is far from being exhausted.”
“Tara Oceans was the precursor of Tara’s current research, implementing the protocols in use today”
How was coral health status during Tara Oceans, between 2009 and 2011?
“In 2010, during Tara Oceans, we went to Mayotte where a major bleaching event was taking place. It was affecting both the reef and the lagoon. We sampled coral, and determined the extent of bleaching and which species were the most sensitive to this situation. The reefs we sampled during this expedition were isolated, healthy and little studied. There were many places like that. In 2010, scientists were just beginning to determine bleaching predictors. Now, this information is public.
The first massive bleaching event took place in 1998 in the Indo-Pacific region, the Atlantic Ocean and the Mediterranean Sea. When we conducted our missions, this episode had just been studied on a global scale. This was really the first scientific study dealing with the impact of global warming on coral.”
“In 2010, scientists were just beginning to determine bleaching predictors. Now, this information is public.”
Francesca Benzoni and her team during the safety briefing aboard Tara - © Vincent Hilaire – Tara Expeditions Foundation
What is the overall situation today and especially in New Caledonia?
“Now we clearly know there’s a global issue. In 2016, a massive bleaching episode occurred for the first time in New Caledonia, where I’m currently working. In 2017, however, this phenomenon didn’t repeat here while it devastated the Great Barrier Reef in Australia, already affected in the past.
Over the past decades, we’ve witnessed an increase in global warming. We also know that ocean acidification is associated with rising temperatures. Unfortunately, we’re living in an exceptionally historical period to study these issues.
New Caledonia is an especial coral reef territory. Its biodiversity is extremely rich and it was very healthy until 2016. Since this bleaching event, even though the reef has been spared so far by the surges of mortality that affected Australia and despite its resilience, it’s more vulnerable than it used to be.”
Unfortunately, we’re living in an exceptionally historical period to study these issues.
Core drilling of a Diploastrea by dive master Jonathan Lancelot - © Florent Cadé – Tara Expeditions Foundation
Should we expect a bleak future for worldwide coral?
“Coral lifetime is much shorter than that of a reef. Therefore, reefs won’t disappear immediately, even if corals die. However, we’ll witness changes in marine community compositions after increasingly frequent bleaching episodes.
Will species migrate to cooler waters?
“It is certain that changes will occur in coral communities. Some species will prevail and others will or won’t adapt. These changes are already in progress and over time, the cards will be re-dealt. Everything can get disrupted. Therefore, we urgently need to identify and understand resilient species and how they respond to climate change.
It is clear that major changes are currently occurring underwater. Even if we better understand ongoing degradation factors and processes, their dynamics still elude us.
Tara Pacific’s innovation is to take into account microbial context to study coral health and it’s the right approach. But we’re far from understanding all of the complex interactions.
In New Caledonia, we’ve already begun to draw up general lists of species expected to survive or perish in the future. However, the Caledonian lagoon is an entity with its own characteristics. It is therefore essential to conduct studies on a global scale.
With Tara Pacific, we’ve undertaken a study on a gigantic scale. It’s an enormous challenge and the whole point of these expeditions. They will significantly advance our knowledge.”
*IRD-UNC (Institut de Recherche et Développement – Université de Nouvelle-Calédonie): Research and Development Institute – University of New Caledonia
**Entrecasteaux-NC 2017: Entrecasteaux-New Caledonia 2017
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