EXBODI / Last day of work before the switch of scientific teams
10 September 2011
For this last day, our work takes place off the Sarcelle waterway where we spotted a seamount with a flat top as shallow as 400 m. Around this structure, le bottom is relatively flat and the depth is about 800 m.
We bring back a large quantity of relatively large sponges, as well as a nice population of gastropods in the genus Bolma.
This genus is part of the biological models that we targeted in Magalie Castelin’s PhD work to study the connectivity between seamounts in the New Caledonian EEZ. These gastropods are part of the Vetigastropods. They possess larvae with short lifespan in the plankton, thereby giving them a limited dispersal capacity.
In addition, as demonstrated by our trawling sample, populations form dense patches and a collection can bring a great number of specimens. However, this study of connectivity remains unfinished because Magalie’s very first analyses revealed that the taxonomy of this genus was problematic and that the borders between the species needed to be reexamined before we could think about a connectivity study.
This day also saw other interesting samples brought back to the surface: a coconut from the summit of the seamount and a large piece of palm leaf from the base of the seamount were both heavily colonized by the mussels that Justine is studying.
At 800 m, on the same fibrous palm leaf, we also collected a fungus that was recently described by Joëlle Dupont based on samples of sunken wood collected in Vanuatu in 2005. In honour of the vessel ALIS, this fungus was named Alisea longicolla. This is the first occurrence of this fungus outside of Vanuatu.
Pour en savoir plus
Castelin M, Lambourdière J, Boisselier MC, Lozouet P , Couloux A, Cruaud C, Samadi S. 2010. Genetic structure, speciation pattern and endemism in poorly dispersive gastropods living on the New Caledonian slopes and nearby seamounts. Biological Journal of the Linnean Society. 100: 420–438.
Castelin M, Puillandre N, Lozouet P, Sysoev A, Richer de Forges B, Samadi S. 2011. Patterns of species richness and endemism of mollusks on seamounts and slopes: disentangling sampling biases, taxonomic impediment and biological factors. Deep-Sea Research Part I. 58: 637-646.
Dupont J, Magnin S, Rousseau F, Zbinden M, Frebourg G, Samadi S, Richer de Forges B, Jones G. En révision. Molecular and ultrastructural characterization of two Ascomycota found on sunken wood in the deep Pacific Ocean, off Vanuatu Islands. Mycological Research. 113: 1351-1364.