Sorting the catch
French scientists have been busy sorting, analysing and distributing thousands of invertebrate and fish specimens collected between Terre Adélie and George V Land in East Antarctica.During the Collaborative East Antarctic Marine Census (CEAMARC), Australian and French scientists on board the Aurora Australis sorted tons of benthic organisms (those that live on the sea bed) and demersal fishes (those living close to the sea bed). They collected a total of 3630 samples, each being composed of one to several individuals. All these samples were labelled and fixed in ethanol (benthic organisms) or formalin (fish), and stored in drums. Most of this material, except for the cephalopods, was sent from Hobart (Australia) to the Museum National d'Histoire Naturelle in Paris (MNHN), where it was sorted again to obtain a more accurate separation of each group. One assistant working full-time for one year re-sorted the material to 5633 samples (not including fish, which were identified and studied separately). This assistant was helped by scientific specialists for some of the groups, and by invited scientists from other French institutions or other countries.
Once the samples were entered into the MNHN databases, they were progressively sent to specialists in museums and institutions all over the world (Australia, France, Germany, USA, UK, Belgium, Chile and South Africa) where they are now being studied. The data obtained from these studies are being shared through the Marine Biodiversity Information Network of the Scientific Committee on Antarctic Research (SCAR-Marbin). This work will contribute to a substantial increase in Australian and French national collections.
The analyses of the collections are already well advanced. While molluscs, crustaceans, cnidarians and pycnogonids are still being identified, studies of some other groups are almost complete:
- All the sea squirts have been analysed, resulting in 33 species being recognised, including three new deep water species.
- All sea stars have been entered into the MNHN databases, photographed and sequenced.
- Of the more than 1000 feather star specimens collected, all have been sequenced, and five species of feather stars have been identified.
- Nineteen species of sea urchins have been identified, including two very rare, deep water ones.
- Of the 2500 teleost (bony) fishes caught, 530 have been photographed and sequenced.
- Before CEAMARC, only 21 demersal fish species had been recorded in this sector, which now incorporates 67 species, including some very rare species and a new Zoarcid (an eel-like fish).
Such taxonomic and phylogenetic studies are prerequisite to any ecological study. The results from this research voyage are already, or will be, integrated into a series of wider projects encompassing biogeographic mapping of the Southern Ocean. A very precise overview of this high biodiversity and of its various assemblages should be rapidly obtained, as scientists have at their disposal accurate identification tools, complemented by oceanographic parameters, information on the substrates (such as rocks, sand or gravel), and videos and photographs. All organisms that have been sequenced will significantly enrich the Barcode of Life database (a repository of DNA sequences).
The calving of an enormous iceberg from the Mertz Glacier tongue in February this year will likely affect local ocean circulation in the CEAMARC study region. This may have a serious impact on the local marine environment, as its scouring effects will probably reach depths of 400–500 m. Contrary to similar important iceberg calvings recently observed elsewhere in Antarctica, this one has been preceded by very detailed in situ analyses of the benthic assemblages. This should allow for a precise estimate of the importance of the impact of the calving and should lead to further studies of how benthic organisms and demersal fish have responded to it.
NADIA AMEZIANE and CATHERINE OZOUF-COSTAZ,
Museum National d'Histoire Naturelle and Centre National de la Recherche Scientifique, Paris