Genetics and tRophic Analysis of dugongs in New Caledonia

 

PROJECT SUMMARY

Dugongs (Dugong dugon) are considered vulnerable to extinction by the IUCN. Dugongs are mainly herbivorous marine mammals and are found in coastal seagrass beds in 48 tropical and subtropical countries between East Africa and Vanuatu. In several of these countries, they are threatened by direct (consumption) and indirect (habitat loss, entanglement in fishing gear, collisions, pollution) anthropogenic pressures that induce high risks of local extinctions. However, they play an essential role in the coastal ecosystems of the Indo-Pacific, in particular by regulating the ecosystem services provided by the sea grass beds. In New Caledonia, the dugong population is estimated at about 700 individuals. Although small, it is the largest concentration of dugongs in Melanesia and one of the largest populations in the world.  Recently, studies carried out in New Caledonia have made it possible to estimate the size of the population, to know its distribution and to quantify the occupation of different habitats by dugongs based on the behavior and movements of individuals monitored by telemetry. Genetic studies suggest that this population is highly vulnerable due to its low genetic diversity and its isolation from Australian populations.

The fragmentary knowledge on diet and genetic characteristics still limits our ability to predict the evolution of the New Caledonian dugong population in the face of habitat anthropization and climate change. These topics are therefore priority research areas.

OBJECTIVES

From samples collected from stranded individuals or studied during tagging missions, this research project will use molecular biology techniques to study the genetics and trophic ecology of the New Caledonian dugong population. Two objectives are identified:

(1) To assess the genetic diversity and isolation of the New Caledonian dugong population from other Indo-Pacific populations;

(2) To study the temporal evolution of the dugong diet at the population and individual level using isotope analyses.

REFERENCES

Cleguer, C., Garrigue, C., & Marsh, H. (2020). Dugong (Dugong dugon) movements and habitat use in a coral reef lagoonal ecosystem. Endangered Species Research, 43. https://doi.org/10.3354/ESR01061

Cleguer, C., Garrigue, C., Fuentes, M., Everingham, Y., Hagihara, R., Hamann, M., Marsh, H. (2017). Drivers of change in the relative abundance of dugongs in New Caledonia. Wildlife Research, 44(4), 365–376.

Cleguer, C., Grech, A., Garrigue, C., & Marsh, H. (2015). Spatial mismatch between marine protected areas and dugongs in New Caledonia. Biological Conservation, 184(0), 154–162. https://doi.org/http://dx.doi.org/10.1016/j.biocon.2015.01.007

Cleguer, C. (2015). Informing dugong conservation at several spatial and temporal scales in New Caledonia. Université Pierre et Marie Curie, Paris (France); James Cook University, Townsville (Australie).

Garrigue, C., Patenaude, N., & Marsh, H. (2008). Distribution and abundance of the dugong in New Caledonia, southwest Pacific. Marine Mammal Science, 24(1), 81–90. https://doi.org/10.1111/j.1748-7692.2007.00173.x

Hagihara, R., Jones, R. E., Sobtzick, S., Cleguer, C., Garrigue, C., & Marsh, H. (2018). Compensating for geographic variation in detection probability with water depth improves abundance estimates of coastal marine megafauna. PLoS ONE, 13(1). https://doi.org/10.1371/journal.pone.0191476

Marsh, H., Penrose, H., Eros, C., & Hugues, J. (2002). The Dugong (Dugong dugon) Status reports and action plans for countries and territories in its range. Nairobi, Kenya: United Nations Environment Programme.

Scott, A. L., York, P. H., Duncan, C., Macreadie, P. I., Connolly, R. M., Ellis, M. T., ... & Rasheed, M. A. (2018). The role of herbivory in structuring tropical seagrass ecosystem service delivery. Frontiers in plant science, 9, 127.