The South African Coelacanths
An expedition in South Africa enabled scientists from the French Muséum national d’Histoire naturelle and the South African Institute for Aquatic Biodiversity, accompanied by a team of deep sea divers, to study the coelacanths’ biology and behaviour more closely. The results of this mission will enable a better understanding of the evolutionary history and ecology of these animals, which are close relatives of land vertebrates, and contribute to the conservation policy for coelacanths, now in great danger of extinction.
In April-May 2013, during a 40-day mission in Sodwana Bay, in iSimangaliso Park at the Ezemvelo Nature Reserve on the east coast of South Africa, new scientific data was obtained for a population of coelacanths discovered in 2000. This coelacanth population is the only one known in the world which is accessible to deep sea divers. This population’s ecosystem exists at a depth of 120 m, not in fact as deep as those of other known populations in the Indian Ocean, which are generally found at depths of between 200 and 400 m.
With the humans able to be so close to the animals, precise experimental and non-invasive protocols could be set up under conditions which did not disturb the animals. The deep diving conditions are challenging, with strong currents, often difficult sea conditions and the time for studying the coelacanths in situ limited to 30 minutes for a decompression stop time of 4 to 5 hours.
The scientific protocols were designed to be the least dangerous for the divers, the least disturbing for the animals and to answer the crucial questions regarding coelacanth biology and conservation. Most of these protocols require a brand new methodology involving all kinds of expertise and experience. An excellent example of scientific multi-disciplinarity for the benefit of the study and conservation of marine ecosystems and species. The main objectives are:
- to provide information about the composition and distribution of the coelacanth population in Sodwana Bay by exploring new underwater canyons, thereby completing the catalogue of listed individuals
- to become acquainted with the physical environment and the flora and fauna around the coelacanths
- to understand the circadian activity patterns and the long- and short-distance movements (in and outside the Sodwana Bay Reserve), as well as the vertical migration of the coelacanths in this population
- to analyse the genetic distribution and rates of individuals in this population
- to study the functional morphology of the coelacanths, particularly their method of locomotion
- to understand the coelacanths’ social behaviour, especially their family groupings and the ways individuals communicate with each other
The scientific and technical synergy between the researchers from the Paris National Muséum of Natural History, the South African Institute for Aquatic Biodiversity, and the deep sea divers in the Andromede Oceanology team meant that a considerable number of scientific protocols were completed with the aim of significantly improving our knowledge of the biology and behaviour of coelacanths. The results of these studies will inform and facilitate reflection on the best conservation policy for this rare and iconic species in the evolution of vertebrates.
The research team is made up of scientists from the French Muséum national d’Histoire naturelle, the South African Institute for Aquatic Biodiversity (SAIAB, Grahamstown) and the South African National Biodiversity Institute (SANBI, Cape Town). The deep sea diving team is made up of French divers led by Laurent Ballesta (Andromede Oceanology) and South African divers (Triton Dive Charter). This mission was made possible thanks to the support of fine watchmakers Blancpain, the coproduction of a documentary film for ARTE France by Les Films d’Ici, Andromede Oceanology, CNRS Images, and the French Muséum national d’Histoire naturelle, the CNRS and the LabEx BCDiv (Biological and cultural diversity: origins, evolution, interactions, future).
Gaël Clément, a professor at the Muséum national d’Histoire naturelle (Department of Earth History, UMR MNHN/CNRS/UPMC CR2P), responsible for the conservation of the collection of fish fossils and a palaeontologist specialising in the evolutionary history of coelacanths and the origin of tetrapods.
Jean-Benoit Charrassin, a senior lecturer at the Muséum national d’Histoire naturelle (Department of Aquatic Environments and Populations, UMR MNHN/CNRS/UPMC/IRD 7159 LOCEAN), and an ecologist specialising in the telemetry monitoring of marine mammals and birds.
Régis Debruyne, a research engineer at the Muséum national d’Histoire naturelle (Department of Taxonomy and Evolution, UMS MNHN/CNRS 2700 OMSI), and a palaeogeneticist specialising in molecular phylogenetics.
Thierry Decamps, a design engineer at the Muséum national d’Histoire naturelle (Department of Ecology and Biodiversity Management, UMR MNHN/CNRS 7179), and a specialist in biomechanics and functional morphology.
Hugo Dutel, a PhD student at the Muséum national d’Histoire naturelle (Department of Earth History, UMR MNHN/CNRS/UPMC CR2P and Department of Ecology and Biodiversity Management, UMR MNHN/CNRS 7179), and a specialist in functional morphology in coelacanths.
Marc Herbin, a senior lecturer at the Muséum national d’Histoire naturelle (Department of Ecology and Biodiversity Management, UMR MNHN/CNRS 7179), responsible for the conservation of the collection of specimens in fluid, a neuroanatomist and a specialist in functional biology of locomotion.
Angus Paterson, director of the South African Institute for Aquatic Biodiversity (SAIAB), Grahamstown, South Africa, a marine biologist.
Kerry Sink, South African National Biodiversity Institute (SANBI), Cape Town, South Africa, a biologist and a specialist in the protection of marine biodiversity.
Professional diving team
Laurent Ballesta (marine biologist and photographer) and his team of deep water divers: Florian Holon (marine biologist), Thibault Rauby and Yanick Gentil. This team from Andromede Oceanology was supported on the surface by Jean-Marc Belin and Pierre Descamp.
Peter Timm and his diver support team (Triton Dive Charter).
Photographers: Laurent Ballesta (underwater photos), Barbara Brou (land photos)
Blogger: Manuel Lefèvre
Film crew: Co-production by Les Films d’Ici, Andromede Oceanology and CNRS Images of a documentary film for ARTE (1 hour 30 minutes): Gil Kebaïli (director), Cédric Gentil (assistant director), Olivier Chasle (cameraman) and Alexis Barbier Bouvet (sound recordist).
Not to mention Dr. Emmanuel Blanche, a specialist in subaquatic and hyperbaric medicine, who, apart from monitoring the divers, luckily only had to take care of the scientists’ bumps and bruises on land…