The stars of Villefranche-Sur-Mer

29 November 2018

Joost Mansour and Andreas Norlin, MixITiN ESRs, report from the French Riviera

After weeks of drafting up experiments and planning for all possibilities, we found ourselves on the brink of autumn when the heat of an extraordinarily hot summer in Europe had started to fade. That is when our ‘mission’ and search for endosymbiotic Radiolaria in the bay of Villefranche-sur-mer, Côte d’Azur, began. These Radiolaria were to be the stars of our stable isotope experiments; we wanted to find out how these organisms take up carbon and nitrogen.

Enjoying a quick tour of Villefranche-sur-mer

On Sunday, September 16, four of us from Team MixITiN arrive in town, we were finally ready to start our first Radiolaria-mission. We start with a “lift” on the laboratory boat to the Observatoire Océanologique de Villefranche Sur Mer. After the necessary ‘corridor sessions’ of introductions and coffee (of course), we unpacked and set up our equipment for the experiments before venturing out to sea to find our Radiolarian stars. Armed with different sized plankton nets we were prepared for the unpredictable. Collodarian colonies can be seen by the naked eye. Right from the first tow we were thankful that Lady Luck was with us, offering us a good amount of Collodaria for our experimental set up.

Getting ready to set sail

Eager to get the experiments started, we sorted the Collodarian colonies into individual containers. We continued to check under stereomicroscopes what we had from our plankton sampling tows. We saw a plethora of different shapes but one shape dominated; small star shaped Acantharia with 20 thin spicules extruding from an often spherical cell-centre. You can see them here:

The sampling of the first day seemed to be a success. The Collodaria just needed some rest; after 24 hours we would be ready to set up our first experiment with these Radiolaria. In the meantime there were plenty of Acantharia for us to isolate; with great eagerness we started sorting and isolating the tiny stars of the sea.

Happy with our success on the first day we could not wait to start the next day. Unfortunately, this time Collodaria were very sparse. We shifted our focus to the smaller sized nets. We checked the new water samples to see what we had brought back – did we have the same Acantharia species as the previous day?! We did find some and so with some hope we went to check our cells from the previous day. Here again we met with disappointment – nearly all the acantharian cells were in bad shape. Fortunately, on the bright side, most of the Collodaria were still in great shape so we could begin our first experiment!

The first few days taught us a lot; we realised that we would not necessarily be able to “shop” for our preferred Collodarian species during our daily sampling in the bay. We learnt to identify the robust acantharian cells that could survive being handled versus the “delicate” acantharians which could not survive a night in the laboratory and which deteriorated overnight.

Our daily routine became very clear: (i) sampling on the boat; (ii) sorting and isolating the Collodaria (if any) into individual containers; (iii) identifying and sorting the smaller Acantharia until we had about 150 cells to set up our experiments. All our days went by like this.

Radiolaria are beautiful, single-celled protists, which occur in various fascinating shapes, it is very easy to get distracted from the sorting task. Some Acantharia look like small twinkling stars while others like little windows to the Milky Way or even small hovercrafts! But words cannot do justice to these fascinating oceanic greenhouses. Have a look at our photos – a picture can often say more than words:

The weekends gave us a tiny window of opportunity to explore the French riviera with diving, hiking and just enjoying the warm weather. We went hiking through the neighbouring area, and climbed up to the fortification that make up the old town of Éze.

The rewarding sights of some diving and climbing

By the end of our two weeks we had completed four experiments on two groups of Radiolaria. After our first successful ‘mission’, we packed up for the return trip, back to the grey and cloudy shores of Brittany. We left Villefranch sur Mer with hope that each of our experimental sample contained enough biomass for a CN signal…

Joost Mansour

Andreas Norlin

From the sea along the coast of Belgium to the molecular laboratories in Germany

23 October 2018

Jon Lapeyra, MixITiN’s ESR10, reports from RV Simon Stevin

Running away from the European capital of Brussels, on an early morning in summer we arrive at the port of Oostende. Fresh air! The research vessel (RV) “Simon Stevin” from VLIZ is already waiting for us along with a very welcome cup of coffee. A big thank you to the crew!

As soon as we get our sampling equipment into the ship’s laboratory, our project briefing begins. We are going to sample nine stations along the Belgian coastal zone in 48 hours. Our aim? … sampling the planktonic community; especially mixotrophs, of course!

At each sampling station the RV Simon Stevin stops for 20-30 minutes, depending on the requirements of the different scientists on board. A range of different sampling equipment are deployed: a CTD (an oceanography instrument to measure Conductivity, Temperature, and Pressure), Niskin bottles to collect water and Secchi disks to measure the water turbidity. Also, we take surface water and benthic samples at different depths ranging from 10 to 35m. Why? Because within MixITiN one of our aims is to understand the impact of environmental conditions on the mixotrophic plankton communities and one of my jobs is to carry out monthly sampling throughout the year off the Belgian coast.

Alongside the field sampling, in the ship’s laboratory we carry on identifying, sorting and preserving samples for later analysis. Through the microscope we look at the living organisms as soon as we get them out of the water. In this way, we can have an overview of what is present in the water so that we can isolate what we need for the analysis of their genes. Also, we always hope to get lucky and observe some mixotrophs predating over what one may consider to be their predator!

Filters of the seawater ‘content’ are collected and quickly frozen; DNA from these was going to be extracted at the ‘Université Libre de Bruxelles’ and finally sequenced at the Alfred Wegener Institute (AWI) in Germany; both MixITiN consortium institutes where I am conducting my research as a Marie Sklodowska Curie Actions Early Stage Researcher (ESR). While I carry on sampling on RV Simon Stevin, I wonder…. how diverse and abundant are the mixotrophs among the planktonic community going to be?  What functional types will I find in the Southern North Sea?

Sampling done, on our way back to the shore, we spot a ‘red tide’ not far from our last sampling station. A Noctiluca bloom! A great opportunity to get fresh samples of one of the most iconic species of the plankton community. Noctiluca scintillans form bioluminescent blooms in our seas and oceans globally. So we were very excited – are these particular cells bioluminescent?

We test them in the dark, however unfortunately these particular Noctiluca were not bioluminescent. Off this coast of Belgium we only see the heterotrophic Noctiluca, but increasingly in the Indian Ocean and West Pacific they see a mixotrophic version (“Green Noctiluca”), harbouring intact green algae actively growing inside their erstwhile predator. Perhaps with climate change we will eventually see this form in the English Channel? Almost at the end of our journey, the Captain of the RV Simon Stevin announces through the speakers that a ‘man over board’ manoeuvre was going to take place. Good for us in that this is a warm and sunny day and that we are going to have a chance to swim in the middle of the North Sea, where the land is just a distant memory…..

John Lapeyra Martin

Plant or Animal? Why Not Both!

9 October 2018

Filomena Romano, MixITiN’s ESR5, took the mixotroph paradigm to the 2018 MSCA Researcher’s night celebrations at Crete.

The Hellenic Center for the Marine Research (HCMR), Crete

I attended the MSCA Researcher’s night at the Hellenic Center for the Marine Research (HCMR) on Friday 28th September. I gave a Powerpoint presentation in the hall of the institute. The opportunity to talk about mixotrophs for the first time made me really excited because it was a chance for me to improve my communication skills. At the same time, I was worried about the language. I am not able to speak Greek, to me that represented a major problem. I was afraid to not be able to communicate with young children.

Here you can find the presentation, please have a look!

I also made a poster using the slides from my Powerpoint presentation to attract more people and engage them in discussions about mixotrophs and the oceanic foodweb.

Me and my “mixotroph stand”

My talk and poster were focused on the land and marine-based trophic chains, introducing the concepts of autotrophy and heterotrophy. I did not go into details of mixotrophy. I specifically wanted the audience to form their own ideas of mixotrophy prior to introducing them to the subject. Thus at the end of my talk, I asked all the attendees to draw how they thought a mixotroph could look like.

Some examples of what the audience thought mixotrophs should look like

At my station I had some cards ready with the pictures of different types of plankton including mixotrophs. I used these not just to show examples of mixotrophs but also for playing a “memory” game. This latter activity was particularly useful for introducing the concepts of the microbial food web to the audience.

Talking about mixotrophs

During the evening I interacted with:

  • 7 children (5-8 years old);
  • 5 teenagers (10-15 years old);
  • 11 adults.

… a total of 23 people.

While I delivered an outreach event on mixotrophs to school pupils earlier this summer, I did that with my fellow MixITiN ESRs. At the Researchers’ night I worked on my own. I found the experience interesting and funny. For me, what went well was introducing the mixotrophy concept; people appeared to be really interested. It was also nice to let people draw how a mixotroph could look like. For next time I plan to have more interactive activities. This will help me to communicate directly with all age groups from the very young children to the adults.

Filomena Romano

Gaining fresh perspectives at Deltares

July 2018

Deltares is located close to the beautiful historic Dutch town of Delft, origin of the prized Delft blue pottery and home to the Dutch royal family.

Little canals cut everywhere through the town and the surrounding idyllic, windmill-sprinkled landscape. The canals and lakes are richly populated by a plethora of waterfowl, all of which were busy raising their young during our stay. Biking to work every morning smelling green fields was nice.

The non-profit institute focuses on applied aquatic research with a strong emphasis on policy making and draws from multiple disciplines in science with an extensive international network.  Its aims include the enabling of sustainable life in coastal regions and management of ecosystem services. As the MixITiN project aims to train us in international networking while many mixotrophic organisms link into subjects of ecosystem management, economics and social sciences, our secondment at Deltares gave us new insights into this working environment in contrast to our previous backgrounds.

Learning how to communicate our research to engineers, policy makers and the general public enabled us to see our topics from a different perspective. It made us realise important aspects of our topic formerly hidden from our perspective of pure scientific interest. We got a sense of real life application of research by learning about large scale models and European policies for the marine environment. Since we may have prematurely dismissed policy making as a dry subject compared to science, our experience at Deltares was surprisingly positive.

The working atmosphere was relaxed, we met very skilled and warm people to enjoy the life of the institute with. Needless to say, harmony and cooperation were the pillars of our joint team work. The secondment was mind opening, enabling us to take on the perspective of policy makers. And we guess this was the goal indeed!

Anna Anschütz

Maira Maselli

Claudia Traboni