Waggle danse

Ants create a lifeboat in the Amazon jungle - BBC wildlife

PhD in "Biogeochemistry and ecosystems": Bioturbation – Bioirrigation – Benthic prokariotic communities

Title: The effects of bioturbation on the diversity of the prokaryotic communities in the sediment, and study of bioirrigation in ecologically contrasted habitats.

 

Abstract

The Arcachon bay shelters a Zostera noltii meadow (marine phanerogam) which covers the majority of the shore (about 70 km² in the 80's), but which undergoes a drastic regression since 2005 (about 30 % of area less in 2007 compared with 1989). Recent studies have demonstrated the ecological and biogeochemical importance of these meadows. Bioturbation activity of benthic invertebrates generates both a particulate reworking and a transport of porewater (bioirrigation). Bioturbation modifies the physical, chemical and biological properties of the sediment-water interface and thus exert a control on sediment biogeochemistry, mainly via a modification of the specific and/or functional diversity of the benthic prokaryotic communities. In this context, this PhD has two main objectives:  1. To measure the spatio-temporal variations of the bioirrigation activity of the benthic fauna in the Arcachon Bay; 2. To study the influence of bioturbation on the diversity of the benthic prokaryotic communities (bacteria and archea) of the Arcachon Bay.

In the recent context of meadows regression in Arcachon Bay, the consequence of this regression on biogeochemical cycles needs to be addressed. In order to evaluate the impact of this regression on bioirrigation activity, the first objective of the thesis is to measure the bioirrigation activity of the benthic fauna in several habitats: naked sediments, sediments covered with a low density meadow (i.e. in the regression area) and sediments covered with a high density meadow. Bioirrigation has still never been measured in Arcachon Bay. To analyse the spatial variability, studies will be realised in three stations, localised on different levels of the confinement gradient of Arcachon Bay, with three sampling sites by station (three meadow densities). A seasonal follow-up will also be done in one of the three stations, to estimate the temporal variability. Measurements will be done using an ex-situ method developed at the laboratory and based on the monitoring of the decrease of fluorescent dissolved tracer in the water column with fluorimetric sensors.

The second objective of the thesis is to study the influence of bioturbation on the taxonomic and functional diversity of the benthic prokaryotic communities (bacteria and archea) of the Arcachon Bay. This research topic is emergent and important as most of the diagenetic processes are directly or indirectly controlled by prokaryotes, but it has been little studied in the Arcachon Bay. The effects of the various functional groups of bioturbation on the total number of prokaryotes (flow cytometry), on the taxonomic diversity of prokaryotic communities (ARISA for bacteria, tRFLP for archea), as well as on the functional prokaryotic diversity (cultural approaches and/or SIP-ARISA), will be analysed. Studies will be realised both in-situ and experimentally. In order to follow the spatio-temporal dynamic of the interactions between bioturbators and prokaryotic communities, sediment sampling for analyses will be done at different times, in different zones of the burrows belonging to different functional groups of bioturbation, and at various distance from the burrows.

This PhD thesis, based in Arcachon Marine station, is interdisciplinary between benthic ecology and microbiology. Studies will be developed both in the field and experimentally.

 

Scientific collaborations outside EPOC laboratory

-Franck Gilbert (UMR 5245 ECOLAB)

-Philippe Cuny (UMR 6117 LMGEM)

 

Contact

-Frédéric Garabétian: f.garabetian@epoc.u-bordeaux1.fr  (director of the PhD, Pr. Univ. Bx1)

-Aurélie Ciutat: a.ciutat@epoc.u-bordeaux1.fr (co-director of the PhD, CR CNRS)

 

 

Laboratory

EPOC UMR 5805 - Team ECOBIOC - Arcachon Marine Station, France.

 

Application

This PhD thesis is for a graduate student highly motivated by doing research. The candidate will have to be either a microbiologist with a strong interest for benthic ecology, or a benthic ecologist with a strong interest for microbiology. As the funding for the PhD will be a ministerial grant awarded according to the merit of the candidate, the candidate needs good academic results.

 

If you are interested by this PhD thesis, please send a curriculum vitae and a cover letter detailing your research activities and your expertise, to the two directors of the thesis.

 

To apply to this position, please visit the web site of the Doctoral School "Sciences and Environnements" from Bordeaux 1 University: ici.. Deadline for application: 09/05/2011.

Journal of Visualized Experiments

Journal of Visualized Experiments (JoVE) is a peer reviewed, PubMed indexed journal devoted to the publication of biological research in a video format.

The Journal of Visualized Experiments (JoVE) was established as a new tool in life science publication and communication, with participation of scientists from leading research institutions. JoVE takes advantage of video technology to capture and transmit the multiple facets and intricacies of life science research. Visualization greatly facilitates the understanding and efficient reproduction of both basic and complex experimental techniques, thereby addressing two of the biggest challenges faced by today’s life science research community: i) low transparency and poor reproducibility of biological experiments and ii) time and labor-intensive nature of learning new experimental techniques.

An example here (easuring Caenorhabditis elegans Life Span on Solid Media. George L. Sutphin^{1, 2}, Matt Kaeberlein^{1. 1}Department of Pathology, University of Washington, Seattle, ²Molecular and Cellular Biology Program, University of Washington, Seattle)

The WWW Virtual Library: Model Organisms

[E. coli | S. cerevisiae | Dictyostelium | C.elegans | Drosophila | Arabidopsis | ZebraFish | Xenopus | Mouse | Others]

This site Biosciences is a catalog of internet resources relating to biological model organisms, and is part of thearea of the Virtual Library project. Other organisms are listed under the Virtual Library sections for Genetics and Developmental Biology.


Source: http://ceolas.org/VL/mo/

The project 'Conservation Biology in Europe'

Join the  Εrasmus Intensive Program Greek Summer School-2011 !

The project “Conservation Biology in Europe: building a coherent strategy for the future” is an ERASMUS Intensive Programme (Erasmus IP), in the field of natural environment and wildlife conservation, funded by the State Scolarship Foundation IKY. University professors from six University Departments in Greece, Denmark, Germany, Italy and UK will combine their expertise to offer a high quality multidisciplinary two-week programme to 15 undergraduate students in the rapidly evolving field of conservation biology. 

Zombie ant fungus: four species not one

10/03/2011 

 
Takes over ants' brains before sprouting through their headsMarch 2011: A bizarre so-called zombie ant fungi which takes control over the minds of ants before killing them and sprouting from the insects' heads, has been found to be four separate species, rather than the one originally thought.
The four species, which infect carpenter ants in the Brazilian rainforest, have been discovered and described by David Hughes and Harry Evans, after they noticed a range of different looking fungi emerging from ants' heads.
The fungus can infect an ant, take over its brain, and then kill the insect once it moves to a location ideal for the fungus to grow and spread their spores.
‘It is tempting to speculate that each species of fungus has its own ant species that it is best adapted to attack,' Hughes said. ‘This potentially means thousands of zombie fungi in tropical forests across the globe await discovery.'
'The fungus makes ants travel a long way in the last hours of their lives'In a parasitic death sentence worthy of a B-movie horror story, the fungus turns carpenter ants into the walking dead, gets them to die in a spot that's perfect for the fungus to grow and reproduce. Once infected by the fungus, an ant is compelled to climb down from the canopy to the low leaves, where it clamps down with its mandibles just before it dies.
‘The fungus accurately manipulates the infected ants into dying where the parasite prefers to be, by making the ants travel a long way during the last hours of their lives,' said study leader David Hughes.
After the ant dies, the fungus continues to grow inside it. Hughes and colleagues found that the parasite converts the ant's innards into sugars that help the fungus grow. But it leaves the muscles controlling the mandibles intact to make sure the ant keeps its death grip on the leaf. The fungus also preserves the ant's outer shell, growing into cracks and crevices to reinforce weak spots, creating a protective coating that keeps microbes and other fungi out.
Scientists have yet to discover how they exert such control over their hosts.