PARIS, June 7 — Tara Pacific is the name of a large-scale; two-and-a-half-year mission in the Pacific Ocean, initiated by the Tara Ocean Foundation, which set out to explore the marine life forms of the Pacific, particularly those that are part of a coral reef ecosystem.

The Tara Pacific exploratory mission has led to a number of discoveries, including how climate change affects coral longevity.

While sea turtles are often referred to as the longest-living marine species, corals also have impressive life spans.

Some corals are capable of living for a hundred years or more. Researchers now have some explanations for why some coral species have such long life spans.

A team of scientists analysed samples of two types of coral (Porites and Pocillopora), studying markers associated with health and aging.

Published in the journal Nature Communications, the study describes how telomeres (a protective structure located at the ends of chromosomes) differ from one species to another and affect the life expectancy of these corals. The results show marked differences in telomere DNA length regulation between two distantly related reef-building coral genera.

"The telomere DNA lengths of the short-lived, more stress-sensitive Pocillopora spp. colonies were largely determined by seasonal temperature variation, whereas those of the long-lived, more stress-resistant Porites spp. colonies were insensitive to seasonal patterns, but rather influenced by past thermal anomalies;” the authors of the work detail. Clearly, the more stable the telomeres, the longer the corals’ life expectancy. But none of these corals is immune to climatic variations (heat, cold...).

Longevity is a crucial issue for corals. Because, despite the high life expectancies of some, their survival remains under serious threat from anthropogenic activities: global warming, pollution, mass tourism, overfishing.

According to an English study published in February 2022 in the journal PLOS Climate, 99 per cent of the world’s corals will not withstand climate change. However, Paola Furla, co-author of the study and a teacher-researcher at the Université Côte d’Azur (Ircan laboratory), was quoted by AFP as saying: "Taken together, the studies give us a fairly optimistic picture, for the moment, of coral resistance to environmental change.”

This work comes out of a major exploratory mission carried out by a team of French researchers and orchestrated by the Tara Ocean Foundation.

Carried out aboard a sailing boat for two and a half years (2016-2018) around 32 islands in the Pacific Ocean, this exploration allowed researchers to study "a poorly understood aspect” of these coral reef ecosystems and their biodiversity to acquire "better understanding of the adaptive capacity of certain species,” in the context of climate change; states the Tara Ocean Foundation on its website.

In particular, it led to the discovery of many previously unknown microsocopic biodiversity in coral reefs. — ETX Studio