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Meteor Blog 15.-16. August: New species at dive 225 discovered

erstellt von aahke zuletzt verändert: 23.08.2008 18:56

Being repared again the Bremen ROV QUEST 4000 goes like clockwork. Carole Decker desribes the exceedingly successful dive No. 225 and its new discovered species!

Planetearth Blog

Does the biodiversity of deep-sea organisms play a role for the climate on Planet Earth? Questions all about marine research will be answered directly aboard of the German research vessel Meteor by cruise leader Prof. Antje Boetius and her crew. In cooperation with the geoportal from 17.08.08 to 24.08.08 they contribute a Science-Blog of METEOR expedition M76/3 GUINECO – MARUM research of fluid and gas seeps on the Westafrican continental margin. Technical highlight of the cruise is the remote-controlled under water robot QUEST4000 by MARUM that will be deployed for taking fauna and sediments samples and conduction of in situ experiments. Go on a dive down to places no other human being has ever seen before: explore the fascinating deep-sea fauna and watch the scientists’ work at gas and fluid seeps deep down on the ocean bottom.

Expedition M76/3b is a collaboration of MARUM – Center for Marine Environmental Sciences at Bremen University and its associated institutes MPI and AWI as well as the French research institute IFREMER and the University of Paris.

More Informationen of the Meteor-Blog, an overview of all contributions to the blog and expedition M76/3B:

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15.-16. August 2008 (Author: Carole Decker)

FS Meteor: Shadow
Present Position

15.-16. August: shiptrack

28. Juli 2008: Bild 5Author is Carole Decker, also see BLOG of 28 July 2008.

New species at dive 225 discovered

The aim of the QUEST dive 225 during the night of the 15th to the evening of the 16th August was to explore and sample a new site with clam beds (bivalves of family Vesicomyidae) in the Southwestern part of the REGAB pockmark (Picture 1).

15.-16. August: Bild 1
Picture 1: Map of REGAB with the sites (VA, V1) of dive 225 and previous sampling sites in the North and East.

This site was chosen for dive 225 because it was described as the largest clam field of the REGAB pockmark based on its first exploration by the ROV VICTOR in 2001. Most interestingly, a different species of Vesicomyidae than elsewhere in the pockmark (also see BLOG of 28-07) had been discovered at this site. Together with other biologists involved in the study of the biodiversity of chemosynthetic clams, we wanted to sample this new species with our blade corers to study its bacterial symbionts and adaptations to high sulfide levels, as we had already managed to do for the other species (BLOG of 28-07).

15.-16. August: Bild 2

Picture 2: Samples obtained with a blade corer. We can recognize one individual of “Vesicomya” chuni and a lot of Calyptogena n. sp.

During dive 225 we were able to collect 3 blade corers in two different patches of clam bed, but they contained just a few specimen of this new species (“Vesicomya” chuni). So even in the Southwestern site, the other species (Calyptogena n.sp.) was dominant, which we also sampled in the North and East of the central pockmark (Picture 1). Both species (Picture 2) are currently under description as new species (Calyptogena n.sp.) or re-described as a new genera (n. gen. chuni) by R. von Cosel (Muséum National d’Histoire Naturelle, Paris), and their new names are kept confidential before publication in a scientific journal.

15.-16. August: Bild 3Picture 3: The two species of Vesicomyidae of the pockmark REGAB.

The distribution and the ecology of “Vesicomya” chuni is not yet well known and it has been sampled just twice at the same site. Indeed, the video observation from the ROV does not allow differentiating the two species of Vesicomyidae as they co-occur in the same sulfidic sediment patches. This makes a comparison of their phylogenetic relationship, their bacterial symbionts and their physiology really interesting. Why do such highly adapted organisms with very similar functions share the same niche? Are they competitors? Hopefully, our study will permit to get more information about life, distribution and ecology of this species. For this purpose, the dive 225 was very important and provided us with new film and photo material, as well as with measurements of the community respiration of the clam assemblages, porewater chemistry, and methane and sulfide fluxes.

15.-16. August: Bild 4

Picture 4: The benthic chambers of IFREMER and MPI on the clam beds, also sampled by the MARUM/AWI geochemists for porewater analyses.