Three members of the Plankton Group (Fabrice, Johan and Daniel) had a chance to spend three days in the Aka Jima Marine Laboratory located in a small island off Okinawa, part of the Ryukus, a chain of islands at the southern most tip of Japan. These islands harbour highly diverse coral reefs but have been little explored with respect to plankton.
This trip was organized by Dr. Masanobu Kawachi from NIES (Tsukuba) as part of the JST-CNRS project Phytometagene. Participants also included Hervé Moreau from Banyuls and Dr. Suda from Okinawa University. The samples collected during the trip included :
enrichment cultures for picoplankton
cryopreserved samples for cultures, genetic and genomic analyses
samples for virus isolation
benthic microalgal cultures
acantharian single cell isolates for morphology and phylogeny
We are really grateful to our Japanese colleagues for this wonderful opportunity to discover a very interesting ecosystem and for their warm welcome.
Photo credit : Dr. Masanobu and Suda, Wada and Google maps.
Fabrice Not from the EPPO team led this work. Sebastien Colin and Sarah Romac from Roscoff also participated to the sampling work, as well as Shuhei Ota (Univ. Oslo), Thomas Richard (Univ. Exeter), David Bass (Museum London), Jan Pawlowski, José Fahrni and Franck Lejzerowicz (Univ. Geneva). They collaborated with local scientists, in particular Snejana Moncheva, Vassil Golesmansky and Atanas Palazov (Director of the Institute of Oceanology in Varna).
The Black Sea has particular features (low salinity and oxygen conccentration) therefore a specific sampling strategy has been carried out.
Samplers went on a research vessel for 3 days and conducted the sampling and processing from there on 3 depth + sediments. 3 stations presenting contrasted characteristics for benthos and molecular analysis of planktonic communities were chosen. The core sampling was performed at three depths (i.e. Surf 3m, DCM 40m, Anoxic 250m) and sediments (400m). If low salinities were measured at all stations, low oxygen (high H2S) was only met below 200m.
A total of 373 samples were collected, corresponding to microscopy (FISH, FCM, HTM, SEM, cultures, fixation), molecular (DNA, RNA) analyses. Girus sampling were also performed. The sampling team benefited a great help from local scientists and further collaborations concerning data will strengthen this cooperation.
Before the start of the sampling work, a communication event was organised with local journalists by the Institute of Varna. Below is a press release of this press conference, unfortunately the text is quite mysterious...
Photo: from left to right:
Fabrice Not, Roscoff, Chief Scientist
Vassil Golesmansky, Varna, Researcher, local contact
Atanas Palazov, Varna, Director of the Institute
Snejana Moncheva, Varna, Researcher, local contact for organisation
The BioMarKs project (www.Biomarks.org ) joined the Mesocosms experience run by the European Program EPOCA (http://www.epoca-project.eu/ ). This experience aims to study the impacts of ocean acidification on biological and chemical processes that go on in the water column.
This will be done by running a CO2 enrichment experiment using nine mesocosms (8 m high and 2 tons heavy floating frames) in the Kongsfjord of Ny Ålesund, Svalbard, Norway. They contain 17 m long flexible bags which will enclose a column of water of 40 m3. Acidification will be processed in this enclosed water by using gaseous CO2, which will be bubbled into the bags. A range of CO2 concentrations from present values (~385 ppm) to values expected for the middle of the next century (1000 – 1250 ppm) will be settled.
The BioMarKs consortium will study more specifically the protists diversity in the mesocosms (and outside them in natural arctic water), during the 6 weeks of the EPOCA mesocosm experiment (from beginning of June to mid-July).
Sampling will be realized each other day by using zodiacs and by collecting integrated sample water from the column. Filtrations and fixations will be done in the laboratories of the Ny Ålesund Research Station. Samples will be assessed using both microscopical methods and 454 sequencing techniques.
Dans
le cadre de l'ANR Paralex "Rôle des pathogènes naturels dans la résilience
des écosystèmes marins côtiers contaminés par des microalgues toxiques
invasives" (AO "la sixième extinction"), nous disposons d'un
financement de thèse sur le sujet suivant :
Titre : Adaptation locale hôte/parasite: reproduction sexuée et diversité
génétique des populations du dinoflagellé invasif toxique Alexandrium minutum.
Résumé du projet : Ce projet de thèse consiste à étudier la diversité génétique
et la reproduction sexuée du dinoflagellé toxique Alexandrium minutum en
populations naturelles. Cette algue invasive est à l'origine des efflorescences
toxiques observées de façon récurrente le long des côtes Bretonnes. Elle
produit des toxines paralysantes qui sont parmi les plus puissantes au monde.
Récemment, l'existence de pathogènes naturels, tel que le protiste parasite
Amoebophrya sp., pouvant jouer un rôle dans la régulation des efflorescences
d'A. minutum, a été mis en évidence dans l'estuaire de la Penzé. Cette
observation nous amène à nous interroger sur les processus pouvant influencer
la diversité génétique des populations de l'hôte et les répercussions de ces
capacités d'adaptation vis à vis de la virulence de ces pathogènes. En particulier,
nous proposons d'utiliser des outils moléculaires afin de déterminer quelle est
l'importance de la reproduction sexuée dans les populations naturelles de cette
espèce en Bretagne (reproduction sexuée versus asexuée), et quelle est la
variabilité génétique observée dans les populations en étudiant dans les mêmes
sites la diversité génétique des efflorescences annuelles et celle du stock de
kystes dans les sédiments. Nous proposons également d'étudier les interactions
entre les pathogènes et son hôte en testant la virulence et la résistance sur
des souches de provenances géographiques différentes.
Cette thèse s'effectuera sous la direction de Christophe Destombe et Laure
Guillou à la station Biologique de Roscoff et bénéficiera de diverses collaborations
nationales et internationales. Un fort intérêt pour la biologie évolutive est
souhaité.
Après l'obtention du prix Daniel Jouvance en 2009, Aurélie Chambouvet
fait partie des 12 Lauréats du prix Bretagne "Jeunes chercheurs 2010",
et vient de recevoir une mention spéciale pour ses travaux de thèse
soutenus en Février 2009.
The BIOSOPE cruise in 2004 crossed the most oligotrophic region of the world oceans. On board flow cytometry allowed to sort specific picoplankton populations in order to perform genetic analyses.
Two papers just came out presenting some of these data. In the first paper (Shi et al. PloS One, 2009) we use flow cytometry to sort picoeukaryotes and construct 18S rRNA gene clone library, revealing novel groups of uncultivated photosynthetic eukaryotes in particular among Prasinophyceae, Chrysophyceae and Haptophyta. In the second one (Lepère et al. EM 2009), the use of probes targeted agains 16S plastid rRNA confirms the importance of groups such as Chrysophyceae and Haptophyta.
Shi, X. L., Marie, D., Jardillier, L., Scanlan, D. J. & Vaulot, D.
2009. Groups without cultured representatives dominate eukaryotic
picophytoplankton in the oligotrophic South East Pacific Ocean. PLoS ONE 4:e7657 - pdf
Lepère, C., Vaulot, D. & Scanlan, D. J. 2009. Photosynthetic
picoeukaryote community structure in the South East Pacific Ocean
encompassing the most oligotrophic waters on Earth. Environmental Microbiology 11:3105–3117. - pdf