exoCean Laboratory

If there is oxygen in the sediment, carbonate shells can dissolve. Animals in the seafloor can therefore speed up the dissolution of carbonates. Since this process releases alkalinity, which increases the seawater’s ability to store carbon dioxide, worms can be little climate heroes 🪱

Mixing a harmless, fast-degrading chemical into the water helps measure how fast animals in the seafloor pump water into burrows. Coastal sediments mainly have oxygen (brown) on the surface; the rest is oxygen-free (black). Animals bring oxygen-rich water into their burrows – look at that network!

#exoCeanadvent Day 11: Science makes you do strange things. Meet @astridhylen.bsky.social, a postdoc working with carbonate dissolution in coastal sediments. She recently found herself in the middle of a salt marsh, stirring one of the ponds with a (clean) toilet brush taped to a curtain rod.

A table with 2 beers, some oat milk, (fake) butter, porridge oats, peanut butter, one avocado, some bread and a bag of coffee on it. Aim high... ;)

Bonus question: How much do you think this bag shopping cost in Bermuda?

A microscope image of a typical plankton sample fished by a net. In here you can see plenty of tiny crustaceans, foraminifera and pteropods!

Look at these guys! This is the kind of thing we were looking for and bringing back to the lab, for reference that little shrimp is about 1.5mm long. We were looking for (among plenty of other things!) important differences between the Med, and the Sargasso Sea - for example in food preferences.

Tom and Julie went out a few days ahead of the rest of the team to do a last minute check that all the islands and beaches and bars existed.

BIOS, our home for 6 weeks this summer.

#exoCeanadvent Day 10: As winter creeps into Provence we remember warmer days from our fieldwork in Bermuda. We stayed with the lovely folk at @biosstation.bsky.social, like @blancobercial.bsky.social who helped us to look for different foraminifera to catch, than our usual Mediterranean stuff.

No power? No problem. Maxime will filter water using the power of his lungs.

The results did not reveal significant trend among the treatments, suggesting that under the tested conditions, the addition of olivine did not appear to affect foraminifera biology. Good news!

Also, if anyone needs water filtration in the field with no electricity, Maxime is your guy.

% survival of forams by day in 3 different water treatments. All the graphs kinda look the same.

To better understand, we cultured G. truncatulinoides under three treatments (natural, NaOH-enriched, and olivine-enriched seawater) to assess their chemical and biological responses to olivine. Over more than a month, we monitored growth, calcification, activity, and survival.

Olivine is one of the most studied minerals for marine Carbon Dioxide Removal (mCDR) approaches due to its potential to increase seawater alkalinity, and decrease CO2. However, excessive addition can lead to secondary mineral precipitation, and impact calcifying organisms such as foraminifera.

Don't eat that! A large foraminifera trying to eat grains of olivine. It soon realised that they weren't food, but had no problems afterwards, so... not poison!

#exoCeanadvent Day 9: Meet Maxime (again). At @exoceanlab.bsky.social and @climatecerege.bsky.social Maxime has been conducting several experiments focusing on the culture of marine organisms. One project involved culturing foraminifera in the presence of olivine (Mg,Fe)2SiO4, an igneous mineral.

Here's the target, a picture of a foram (about 150 micro metres across). They look like pop-corn, but some of us in the lab can tell species and individuals apart as if they were our pets!

Once finished, these measurements will be combined with CT scans, and modelling to work out exactly what is happening in these first stages of sediment formation, or indeed alkalinity recycling in the water column. Stay tuned for results later in Katoo's project!

Nice set up! When trying ti place a glass sensor mere micro-metres away from a fragile shell, precision is required. Here we have a microscope set-up designed just for this, the probes can be moved by fractions of a mm at a time, all whilst the foram and probe end are visible on a computer or down the scope.

To quantify this initial dissolution action, Katoo is carefully placing recently deceased individuals inside tiny capillary sized tubes, and measuring pH and oxygen gradients near the carbonate shell over several days (roughly sinking time).

A foram carefully lined up beneath the microscope, ready for investigation. 📷 K. Declerk

#exoCeanadvent Day 8: Meet Katoo Declerk's Erasmus+ work. During her internship Katoo is investigating recently dead foraminifera (handily available in our lab!) Forams typically sink to the ocean floor soon after death, but partial or total dissolution can occur before getting there.

After the run, one can even spot the @sulpis.bsky.social « actively stretching »

#exocean advent calendar Day 7!
We are lucky to be based in a pine forest, in Southern France, which means loads of possible walks to discuss science in a wonderful environment. We also like to run together - as we did Friday to finish the week!

Titanium high-pressure reactor under construction (said in the voice of Sia).

Coming soon! Sneak peek 👀 meet the new titanium reactor from our engineering partner Irian Mecatronics. Titanium because saltwater is petty and 1000 bar is rough. Integrated sensors, sampling system… Compact, tidy, and ready to misbehave, in a controlled way (we hope!). 🔧🛠️⚙️

A depress(uriz)ed blobfish, credit: National Geographic (It doesn't look like this in its natural habitat!)

The reactors will sit at ridiculous pressures without blinking, let us stream fluids through like tiny intravenous lines, and give us a view through sapphire windows. Materials, energy, biotech, food… if it likes pressure, or might do something cool under pressure, it’s welcome here.

Schematic of the Deep-C high-pressure reactor and in situ sensors.

#exoCeanadvent Day 6: To study the deepest ocean trenches, we’re building reactors that make our lab behave like the deep ocean. Funded by @erc.europa.eu #Deep-C, they will hold cold seawater at ~1000 bar (10km water) so we* watch pressure shape chemistry and biology 🔬🌊

*mostly @sulpis.bsky.social

We're so good at this Science stuff. Day "5"!

CO2 back until the dinosaurs. The record is patchy, at best! We're working hard to fill all the gaps. Figure from Chalk and Rollion Bard in Elements Magazine 2025. https://www.elementsmagazine.org/boron-proxies-from-calcification-site-ph-to-cenozoic-pco2/

@erc.europa.eu #ForCry aims to take the curves like those in post two much further back in time, looking at warmer intervals to look for the tell tale signs of Earth's climate changing its vibe. Find more details below!

exocean.academicwebsite.com/projects/643...

Hundreds of individual plankton living in controlled CO2 conditions. From Bermuda in the summer, but we do it in France too!

To the lab! With @juliemeilland.bsky.social we catch living foraminifera (calcite growers) and subject them to different CO2 concentrations. We can measure their boron and use the relationship in the past!

Well done if you made it this far, & understood. Get in touch if you want to know more.

A graph showing CO2 data from the ice cores over the last 400 thousand years. Data calculated from boron isotopes is also shown, overlapping (almost) perfectly.

#Boron isotopes (a fancy chemical measurement from tiny shells, like these shown below) can be used to reconstruct CO2, just like the ice cores can in the past (also shown below). A little less precise, but show great potential, especially if we can work out how they work in laboratory conditions.

A schematic graph showing global temperature, plotted against CO2. We know CO2 increases temperature, but the how far and how fast are still not totally constrained. Tipping points, or sensitivity changes could impact this relationship in the future, and may have done in the past.

#exoCeanadvent Day 4: Why did we set up this lab? Part I. What is going to happen to climate as CO2 levels go up? @chalkyoceans.bsky.social and @erc.europa.eu project #ForCry look at CO2 in the past to better understand climate sensitivity. Part of this is making better past CO2 reconstructions.

A jar of deep sea mud sitting on a height adjustable stand. It has microprobes to measure oxygen (respiration, photosynthesis) and pH (dissolution, precipitation, also respiration etc...) at tiny intervals to see what is going on right at the grain interface.

Here comes the final boss: porewater microprofiles, using our favourite tools, pH and oxygen microsensors, made of glass and pure anxiety. Every time one snaps, we just sigh, call our finance manager, and prepare our next monthly order from @unisense.bsky.social. Thanks for the tiny sensors!

Marine and Olivier cutting the core into slices, at the top it can be really liquid and gooey, so we keep it vertically, but lower down it can be almost like a rock. Despite the complaining from Olivier both of them are remarkably mud-free!

Once the cores make it back to our lab, it’s time to get our hands dirty: we slice them like a very unappetizing cake, a couple of cms at a time. If we can, outside of the lab to keep it clean inside. All of that just to rebuild the sediment as it looked on the seabed.

Who did that?? I guess we'll never know... #exoCeanadvent Day 4 has been taken over by one of the researchers...A lesson in cyber security for us all @chalkyoceans.bsky.social.

only Canidae member... yet. Permission and linguistic validation pending on whether we can "culture" mammals.

How could we forget, LAB-rador mascot (not really, but American Labpard doesn't work so well), Jean-Milou [somehow not on @bsky.app yet].

Anglophones you can call him John-Milo.

The people that actually do all the work in exoCean, Right to Left: Jaime, Sonia, Maxime, Matthieu and Astrid. Did you know Lego magnifying glasses actually work? No, us neither!

And yes, you'll be added too if you come to work in our lab, @cerege.bsky.social! @soniachaabane.bsky.social, @jysuarezibarra.bsky.social, and others have their figures already. Find details about the full size versions of all these folk now (or soon) on our website.

exocean.academicwebsite.com

The three PIs of #exoCean in Lego format. Olivier the steampunk moustache man, Julie smiling with her paintbrush (for picking forams) and Tom carrying some blue chemical (probably for his hair).

#exoCeanadvent Day 3: An important part of creating a lab is to be able to plan things in miniature, for this we use #Lego versions of our team, they tend to be a bit cheaper for testing. You may spot some of @chalkyoceans.bsky.social's not so secret wishlist in the background (#nu-instruments).