Tuesday, February 24, 2015
Our poster in Granada, while we are at 19º 29.44' S 165º 00.49 ' E
Our colleague Katy Shoemaker is at the ASLO in Granada (Spain), and she sent us a pic of our poster. Thanks Katy!
Saturday, February 21, 2015
Dead Tricho and friends
The OUTPACE cruise (Oligotrophic to Ultraoligotrophic Pacific Experiment) has finally started! Here we are, just north of New Caledonia, on our first day of sampling. The two days of transit from the harbour until our first station were a little bit hectic. We are 30 scientists onboard performing all sort of biological, chemical and physical analyses, and there were two full containers with materials to unload, set and tight down. It took a while!
We're all set now and the first samples are coming out.
Today we crossed several slicks of what seemed to be dead Trichodesmium aggregating in quite large flocks, easily seen by the naked eye (I'll try to upload a picture later). Onboard qPCR analyses have also confirmed that there's quite a lot of unicellular diazotrophs type B (UCYN-B) here (about 10000 cells per liter). Have a look at our fluorescence microscopy images:
Soon the mesopelagic sampling (200-2000m) will start too hopefully :)
Cheers from the ocean!
Mar
We're all set now and the first samples are coming out.
Today we crossed several slicks of what seemed to be dead Trichodesmium aggregating in quite large flocks, easily seen by the naked eye (I'll try to upload a picture later). Onboard qPCR analyses have also confirmed that there's quite a lot of unicellular diazotrophs type B (UCYN-B) here (about 10000 cells per liter). Have a look at our fluorescence microscopy images:
 |
| Here we see what it seems to be two different kinds of Trichodesmium. The round ones are UCYN-B. |
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| This one looks like Katagnymene. |
Soon the mesopelagic sampling (200-2000m) will start too hopefully :)
Cheers from the ocean!
Mar
Friday, October 24, 2014
Poster at ASLO
As already mentioned in the our last post we will not be able to attend next ASLO meeting, as we will be in a cruise. However, we have submitted an abstract to present a poster. Our collaborator and renowned microbial ecologist Pia Moisander will be there to hang the poster for us.
Our preliminary results from the MoorSPICE cruise in the Solomon and Bismarck Seas show that there is indeed active N2 fixation in the mesopelagic layer. Here in Pia's lab we are exploring which diazotrophs were there. Meanwhile, our colleagues from ICBM in Germany (Thorsten Dittmar group) are working on the DOM composition of our samples.
Soon we'll be able to combine all the pieces from this puzzle :)
For now, besides the N2 fixation activity, very fruitful conversations with our physical oceanographer colleagues (Sophie Cravatte and Janet Sprintall) have lead us to find a very impressive thing: low oxygen waters from the Eastern Tropical South Pacific DO REACH THE SOLOMON SEA!!
These low oxygen waters are commonly stopped by the Solomon Islands:
Our preliminary results from the MoorSPICE cruise in the Solomon and Bismarck Seas show that there is indeed active N2 fixation in the mesopelagic layer. Here in Pia's lab we are exploring which diazotrophs were there. Meanwhile, our colleagues from ICBM in Germany (Thorsten Dittmar group) are working on the DOM composition of our samples.
Stations sampled during the MoorSPICE cruise in March 2014.
Soon we'll be able to combine all the pieces from this puzzle :)
For now, besides the N2 fixation activity, very fruitful conversations with our physical oceanographer colleagues (Sophie Cravatte and Janet Sprintall) have lead us to find a very impressive thing: low oxygen waters from the Eastern Tropical South Pacific DO REACH THE SOLOMON SEA!!
These low oxygen waters are commonly stopped by the Solomon Islands:
Low oxygen waters on density level sigma = 26 kg/m3
And sometimes, these waters can "leak" via Indespensible Strait (Solomon Islands), allowing us to detect them within the core of the Solomon Sea:
Concentrations of oxygen at different density levels in the water column. Note the low oxygen zone at density 25-26 kg/m3. This water comes from more than 13000 Km away!! Isn't that amazing?
Stay tuned :)
Wednesday, September 3, 2014
Small bugs with a big impact: linking plankton ecology with ecosystem processes
The abstract submission for the next ASLO meeting is now open! It would be held in the beautiful city of Granada (Spain). Although DIADOM researchers will not be able to participate directly (as at the time we will be onboard the R/V L'Atalante in the SW Pacific), we are very excited about the sessions that will be presented there.
One of the most interesting ones is probably #24 " Small bugs with a big impact: linking plankton ecology with ecosystem processes". This session is meant for plankton scientists who undertake interdisciplinary approaches to resolve different time and space scale ecological questions.
From our side, we are now analyzing samples from the MoorSPICE cruise (which took place last month of March) to present some results as a poster in the ASLO meeting. We are especially interested in participating in session #28 "The black boxes have just been opened: Linking organic matter composition and microbial diversity in aquatic environments", as it matches very well the purposes of DIADOM: linking diazotrophic activity and diversity to the composition and lability of organic matter.
However, we will miss the opportunity to visit the wonderful city of Granada and its amazing Alhambra:
For more info on the ASLO meeting, please visit http://www.sgmeet.com/aslo/granada2015/default.asp
Cheers!
Mar
One of the most interesting ones is probably #24 " Small bugs with a big impact: linking plankton ecology with ecosystem processes". This session is meant for plankton scientists who undertake interdisciplinary approaches to resolve different time and space scale ecological questions.
From our side, we are now analyzing samples from the MoorSPICE cruise (which took place last month of March) to present some results as a poster in the ASLO meeting. We are especially interested in participating in session #28 "The black boxes have just been opened: Linking organic matter composition and microbial diversity in aquatic environments", as it matches very well the purposes of DIADOM: linking diazotrophic activity and diversity to the composition and lability of organic matter.
However, we will miss the opportunity to visit the wonderful city of Granada and its amazing Alhambra:
For more info on the ASLO meeting, please visit http://www.sgmeet.com/aslo/granada2015/default.asp
Cheers!
Mar
Wednesday, May 28, 2014
The end of the HOTMIX cruise
These days our colleagues sailing onboard the R/V Sarmiento de Gamboa are heading towards the Canary Islands to finish their 45 day cruise, which started on the Levantine basin of the Mediterranean Sea, close to Greece.
The HOTMIX (Dark-ocean water mass boundaries and mixing zones as "hot-spots" of biodiversity and biogeochemical fluxes across the Mediterranean Sea and Eastern North Atlantic) project counts with first class microbial oceanographers and biogeochemists like Javier Arístegui, Pep Gasol, Pepe Álvarez-Salgado and Celia Marrasé, among very promising PhD students and postdocs and professional lab techs and engineers.
The goal of HOTMIX is to link microbial diversity to microbial activity in the deep layers of the Mediterranean Sea, focusing in the boundaries between water masses, where organic matter acumulates and "hot-spots" of microbial activity are likely to appear. Some of the scientists onboard characterize the microbial community by "omics" approaches, some characterize the largely unknown dissolved organic matter (DOM) pool by high resolution mass spectrometry and ultrafiltration approaches, some measure bacterial production with radioisotopes, some quantify bacteria by flow cytometry...
Our DIADOM project partly collaborates with HOTMIX scientists to measure N2 fixation in the depths of the Mediterranean Sea. Our colleague Nauzet Hernández (see picture below) has been taken samples across the Mediterranean in a dark container placed on the fantail of the Sarmiento de Gamboa during the HOTMIX cruise.
Nauzet filtering seawater samples in the darkened container. In the ocean, light disappears at approximately 100-200 m. Thus, if your samples come from deeper layers like 500 or 1000m, you must find a dark way of filtering them to avoid disruption of the microorganisms. In good commitment with his duty, Nauzet is using a headlamp to minimize light-shocks, well done! (Picture taken from the HOTMIX blog, by Javier Arístegui).
The R/V Sarmiento de Gamboa (CSIC, Spain).
The HOTMIX (Dark-ocean water mass boundaries and mixing zones as "hot-spots" of biodiversity and biogeochemical fluxes across the Mediterranean Sea and Eastern North Atlantic) project counts with first class microbial oceanographers and biogeochemists like Javier Arístegui, Pep Gasol, Pepe Álvarez-Salgado and Celia Marrasé, among very promising PhD students and postdocs and professional lab techs and engineers.
The goal of HOTMIX is to link microbial diversity to microbial activity in the deep layers of the Mediterranean Sea, focusing in the boundaries between water masses, where organic matter acumulates and "hot-spots" of microbial activity are likely to appear. Some of the scientists onboard characterize the microbial community by "omics" approaches, some characterize the largely unknown dissolved organic matter (DOM) pool by high resolution mass spectrometry and ultrafiltration approaches, some measure bacterial production with radioisotopes, some quantify bacteria by flow cytometry...
The track of the HOTMIX cruise.
Our DIADOM project partly collaborates with HOTMIX scientists to measure N2 fixation in the depths of the Mediterranean Sea. Our colleague Nauzet Hernández (see picture below) has been taken samples across the Mediterranean in a dark container placed on the fantail of the Sarmiento de Gamboa during the HOTMIX cruise.
Nauzet filtering seawater samples in the darkened container. In the ocean, light disappears at approximately 100-200 m. Thus, if your samples come from deeper layers like 500 or 1000m, you must find a dark way of filtering them to avoid disruption of the microorganisms. In good commitment with his duty, Nauzet is using a headlamp to minimize light-shocks, well done! (Picture taken from the HOTMIX blog, by Javier Arístegui).
The samples will be analyzed in July 2014 at the Mediterranean Institute of Oceanography in Marseille (France). Keep updated for more results!
Mar
Saturday, May 17, 2014
New diazotrophs found in the oxygen-poor waters off Peru
A new paper in the ISME Journal describes new diazotrophic organisms from oxygen-poor waters off the coastal upwelling system in Peru. Researchers from the GEOMAR Helmholtz Centre for Ocean Research and the University of Kiel have sampled DNA and RNA in these waters and designed new nifH gene probes to quantify the abundance and characterize the diversity of diazotrophic microorganims.
These researchers have found a wide range of diazotrophs inhabiting oxygen-poor waters. Remarkably, they found two new nifH clades coinciding with low oxygen and high phosphate waters, conditions which seem ideal for a high N2-fixing activity. A high diversity of proteobacterial diazotrophs was also found. Moreover, N2 fixation rates were enhanced by the addition of glucose, confirming the presence of active heterotrophic diazotrophs.
These findings suggest that (1) N2 fixation needs to be investigated in "unexpected" areas, such as high latitudes and deep basins, but also (2) new probes need to be designed, as limiting nifH analysis to the "classical" probes (UCYN-A-B-C, Trichodesmium, heterocystous cyanobacteria, and gamma-proteobacteria) likely underestimates the real diversity and abundance of diazotrophs.
Check the full paper here.
In the DIADOM project we will investigate deep-ocean diazotrophs in the waters of the SW Pacific Ocean. Keep updated for more results :)
Mar
These researchers have found a wide range of diazotrophs inhabiting oxygen-poor waters. Remarkably, they found two new nifH clades coinciding with low oxygen and high phosphate waters, conditions which seem ideal for a high N2-fixing activity. A high diversity of proteobacterial diazotrophs was also found. Moreover, N2 fixation rates were enhanced by the addition of glucose, confirming the presence of active heterotrophic diazotrophs.
These findings suggest that (1) N2 fixation needs to be investigated in "unexpected" areas, such as high latitudes and deep basins, but also (2) new probes need to be designed, as limiting nifH analysis to the "classical" probes (UCYN-A-B-C, Trichodesmium, heterocystous cyanobacteria, and gamma-proteobacteria) likely underestimates the real diversity and abundance of diazotrophs.
Check the full paper here.
In the DIADOM project we will investigate deep-ocean diazotrophs in the waters of the SW Pacific Ocean. Keep updated for more results :)
Mar
Saturday, May 10, 2014
DIADOM's kick-off
Hi all,
This is the first entry of the DIADOM project blog. The DIADOM ("Interactions between diazotrophs and dissolved organic matter in the ocean") is a postdoctoral research project funded by the Marie Curie Intra-European Fellowships, leaded by Sophie Bonnet and Mar Benavides.
In this project we aim to study diazotrophic nitrogen fixation (or N2 fixation) in the Southwest Pacific, focusing on heterotrophic diazotrophs and their relationships with dissolved organic matter. But... what does this all mean??? Let's see :)
N2 fixation is the process by which atmospheric nitrogen (dinitrogen or N2) is assimilated by microorganisms and transformed into a more bioavailable form of nitrogen: ammonium. The microorganisms called diazotrophs (from the greek di= 2, azo = nitrogen, trophos = nutrition) are the only ones capable of fixing N2, an incredibly tough task which takes a lot of energy.
And why should we care? Well, most of the global ocean surface is poor in nitrogen (the "fuel" phytoplankton use to take up atmospheric CO2), and diazotrophs are capable of bringing this nitrogen from the air into the ocean, boosting primary production and CO2 drawdawn (thus saving us from global warming and allowing the production of 50% of the oxygen we breath)... it really looks like something to care about doesn´t it?
After more than two decades of oceanic N2 fixation studies focusing on the sunlit layer of the ocean (first 100-200 m), now there is some evidence that diazotrophs could be also living in the deeper and mostly unknown dark ocean. The diazotrophs that inhabit these deep waters are inherently different from those living in the sunlit layer of the ocean: the first use organic matter as their nutritious source, while the latter rely on the light provided by the sun and CO2 fixed by photosynthesis.
Our goal is to investigate whether deep ocean diazotrophs use organic matter for their nutrition: which kind of organic matter they use? do different species of diazotrophs use different kinds of organic matter? Overall, we will gain new knowledge on the distribution of poorly studied diazotrophs in the depths of the ocean.
This project will benefit from oceanographic cruises in the Southwest Pacific. One has already finished, check out the MoorSPICE cruise blog here.
This cruise took place in the Solomon Sea between 28th February and 31st March 2014.
The MoorSPICE science party onboard the R/V Thomas G. Thompson
The R/V Thomas G. Thompson docked in Nouméa's harbour.
In July 2014 I will spend a whole month in the Mediterranean Institute of Oceanography (MIO) in Marseille analyzing the samples collected during the cruise. Preliminary results and impressions will be posted, follow us!
Cheers
Mar
This is the first entry of the DIADOM project blog. The DIADOM ("Interactions between diazotrophs and dissolved organic matter in the ocean") is a postdoctoral research project funded by the Marie Curie Intra-European Fellowships, leaded by Sophie Bonnet and Mar Benavides.
In this project we aim to study diazotrophic nitrogen fixation (or N2 fixation) in the Southwest Pacific, focusing on heterotrophic diazotrophs and their relationships with dissolved organic matter. But... what does this all mean??? Let's see :)
N2 fixation is the process by which atmospheric nitrogen (dinitrogen or N2) is assimilated by microorganisms and transformed into a more bioavailable form of nitrogen: ammonium. The microorganisms called diazotrophs (from the greek di= 2, azo = nitrogen, trophos = nutrition) are the only ones capable of fixing N2, an incredibly tough task which takes a lot of energy.
And why should we care? Well, most of the global ocean surface is poor in nitrogen (the "fuel" phytoplankton use to take up atmospheric CO2), and diazotrophs are capable of bringing this nitrogen from the air into the ocean, boosting primary production and CO2 drawdawn (thus saving us from global warming and allowing the production of 50% of the oxygen we breath)... it really looks like something to care about doesn´t it?
After more than two decades of oceanic N2 fixation studies focusing on the sunlit layer of the ocean (first 100-200 m), now there is some evidence that diazotrophs could be also living in the deeper and mostly unknown dark ocean. The diazotrophs that inhabit these deep waters are inherently different from those living in the sunlit layer of the ocean: the first use organic matter as their nutritious source, while the latter rely on the light provided by the sun and CO2 fixed by photosynthesis.
Our goal is to investigate whether deep ocean diazotrophs use organic matter for their nutrition: which kind of organic matter they use? do different species of diazotrophs use different kinds of organic matter? Overall, we will gain new knowledge on the distribution of poorly studied diazotrophs in the depths of the ocean.
This project will benefit from oceanographic cruises in the Southwest Pacific. One has already finished, check out the MoorSPICE cruise blog here.
This cruise took place in the Solomon Sea between 28th February and 31st March 2014.
In July 2014 I will spend a whole month in the Mediterranean Institute of Oceanography (MIO) in Marseille analyzing the samples collected during the cruise. Preliminary results and impressions will be posted, follow us!
Cheers
Mar
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