NEW CALEDONIA DUGONG OBSERVATION, STUDY AND MONITORING PROJECT

Start date: January 2024

The POSEIDON project brings together a wide range of research activities aimed at conserving the New Caledonian dugong. It was launched in 2024, declared the "Year of the Dugong" by the South Province following the reclassification in 2023 of the New Caledonian dugong population, now classified as "endangered" by the International Union for Conservation of Nature.

  • Life cycles and demographics

New Caledonia's dugong population is in decline. Understanding this trend requires a better understanding of the dugong's life cycle and local demography. Knowing the age of the animals in the population or the birth rate of its females (the frequency with which they have young) can help to understand the future evolution of the population.

The project includes training in techniques for estimating age using tooth sections taken from stranded animals. The aim is to perpetuate this skill in New Caledonia, in partnership with James Cook University, so that any future strandings can be fully analysed locally. This work is part of the RESCUE project ("Recenser les échouages de mammifères marins").

  • Population size and genetic diversity

Following on from the initial analyses of mitochondrial DNA (Garrigue et al. 2022), the POSEIDON project will make it possible to carry out analyses of nuclear DNA (microsatellites) and thus characterise in greater detail the structure of the Caledonian population, its connections with neighbouring populations and estimate the effective size of the population, i.e. the number of individuals that participate genetically in the population. This value is used to determine whether there are enough breeding adults to ensure the viability of the population. This work is currently being led by Cécile Fauvelot (IRD UMR Entropie), in collaboration with Janet Lanyon (University of Queensland).

Mark-recapture models are an alternative to genetic models or aerial overflight counts for estimating population size. The POSEIDON project will provide an opportunity to test the feasibility of this method using drone aerial photo-identification data.

  • Health status and links to seagrass ecosystems

Aerial photogrammetry by drone will be used to derive indices of the corpulence and state of health of the dugongs. Over time, these indices will provide a better understanding of how the health of dugongs is affected by changes in their living environment, and in particular by the health of the seagrass beds on which they feed. In this way, we hope to assess the impact that climate change, marine heat waves and coastal development may have on the meadows and therefore on the dugongs.

  • Human dimension and cultural representation

Following on from the Science en Herbe project run by the IRD in 2022, we will be looking at how Caledonians represent and understand this emblematic animal of the lagoon. More than 600 drawings were produced by primary and secondary school children, who were asked to represent "Where does the dugong live? These drawings will be studied and supplemented by interviews to understand the relationship that young New Caledonians have with the dugong. This work is being carried out in partnership with Catherine Sabinot (UMR ESPACE-DEV)

 

INTERNATIONAL CollaboratOrs internationaux

Christophe Cleguer (James Cook University, Australie)

Leigh Torres (Oregon State University, Etats-Unis)

Janet Lanyon (University of Queensland, Australie)