Biopapua / Off of the reefs of Lusancay Islands
09 October 2010
Today, our goal is to work on hard bottoms bordering the Trobriand Trench.
This trench plunges deeper than 5000 m. We are struggling to find adequate areas to work on, but the result is worth the effort.
We accumulate many samples of mollusks, crustaceans and deep-sea corals typical of those substrates.
We find specimens of Nassaria snails, a genus on which Magalie Castelin (MNHN) focused on during her PhD thesis. In this genus, species may have very different shell shapes, depending on the habitat where they are found.
Indeed, in gastropods, differences in shell morphology may not reflect differences between species, but rather environmental differences. In this case, intra- and inter-species variations are difficult to tease apart. Using genetic tools, Magalie’s work showed an unsuspected species diversity within the genus Nassaria .
This is a very satisfactory day for the science team. However, it gives a lot of work to the crew. The trawl net is damaged during the first trawling operation, and the trawl beam breaks during the second. While the science team is busy sieving and sorting specimens, the crew mend the net and change the broken trawl beam.