Biodiversity On The Antarctic Ocean Floor

Bellingshausen Sea

The expedition, aboardthe oceanographic vessel, Hesperides, will shortly be working in theBellingshausen Sea. The reason why these waters have remained almostunexplored is due to its adverse climate which, in turn, has assuredthat human presence has been scarce.

On this present campaign thescientists will trawl the ocean floor at up to 2000 metres depth, usingboth Agassiz-trawl fitted with a closed net as well as a Box-corer.

Thetwo methods are complementary. With the Agassiz-trawl a corridor of thesea floor is swept to catch all the species on the way in a mixed form.On the other hand the Box-corer is cast and once it hits the bottom ittakes a 50cm x 50cm sample thereof for subsequent analysis on deck.With this sample we can quantify the number of each species per squaremetre, its biomass, and so on. Thus it is known as a quantified sampleof the ocean floor.

When the samples arrive on deck they arewashed and classified on board in large groups or rows: sponges,corals, polyquets, molluscs, echinoderms, fish, etc. and arephotographed so that their colour when alive and external anatomy canbe clearly appreciated. Finally, they are inserted in alcohol orformaldehyde for their subsequent analysis in the laboratory.

Identification of a new species

Oncethe animals get to port they are distributed amongst the specialistsaccording to their group. In our case, at the Leioa campus of theUniversity of the Basque Country in Bizkaia, two groups of vermes orsea worms are taxonomically analysed. The aim of this is to identifythe species, to find out if they are new species or belong topreviously described ones.

To this end, both the external and theinternal anatomy of the animal are thoroughly analysed, using hand-lensand microscope. It should be pointed out that these animals measurebetween 1mm and 150mm.

In the laboratory itself photographs areagain taken in order to identify features peculiar tot he animal and,finally, the classification of the species in question is presented inthe specialist literature.

In the previous campaign, expeditionmembers discovered a new species of vermes. The name of the species andits morphological characteristics will shortly be put forward forapproval by the scientific community.

Thus, this exciting task ofanalysing the biodiversity of the marine floor is, little by little,bearing fruit. We trust that it is not too late, given that the expertsclaim that many species are disappearing – even before we know aboutthem.