Over FePhyrus: IJzer (Fe) en virus infecties op Antarctica
Klimaatverandering gaat snel in Antarctica, met name in de kustgebieden van West-Antarctica. Algen, de basis van de voedselketen in zee, hebben het rondom Antarctica al moeilijk door een gebrek aan ijzer (Fe) en sterfte door virusinfecties en worden nu ook door een temperatuurstijging bedreigd. De temperatuurstijging beïnvloedt zowel de toevoer van Fe door smeltende gletsjers als de groei van algen en virussen. Dit onderzoek wil het effect van deze veranderingen bestuderen en daardoor beter begrijpen hoe dit unieke ecosysteem reageert op de klimaatsverandering. Dit is een internationaal project, zoals eigenlijk bijna al het polaire onderzoek, dus de rest van dit blog zal ik het Engels zijn zodat het voor iedereen begrijpelijk is!
About FePhyrus: Iron (Fe) and virus infections in Antarctica
Climate change is happening fast in Antarctica, most notably in the coastal regions of West-Antarctica. Though often regarded as toxins, metals are required as essential micro-nutrients for the growth of all organisms. In the open ocean, the base of the food web is formed by unicellular algae, known as phytoplankton. These microscopic unicellular plants cannot live off just water and sunlight; they need nutrients, including trace metals such as iron. In the ocean surrounding Antarctica, the amount of phytoplankton that can be sustained is lower than expected due to the very low availability of trace metals, notably iron. In contrast, in the coastal seas around Antarctica very dense phytoplankton blooms occur every year when the sea ice opens up. These 'blooms' support Antarctica’s key higher organisms and take up a large amount of atmospheric CO2, but the extent depends on which species is blooming. Which species becomes dominant, and its ability to bloom, likely depends on the availability of macro-nutrients, iron and light, as different species have different requirements. However, much is still unknown about these requirement and the processes that control the availability and cycling of iron in the marine environment. Additionally, grazing and death through viral lysis control the standing stock of the phytoplankton. Viral lysis is a thus far understudied loss factor for phytoplankton, particularly in the Southern Ocean.
The coastal region of Antarctica is currently experiencing dramatic changes as temperatures are rising and glaciers are melting rapidly. Glaciers are a source of iron, but much is still unknown about the importance of this source of iron for phytoplankton, the spatial extent and how this is likely to change. The cycling of iron is strongly affected by the availability of iron to the microbial community, including phytoplankton. Iron solubility and bio-availability depends on the presence of organic molecules, known as ligands. The production of these ligands in turn depends on the composition of the microbial community and the share of viral lysis as source of ligands through cell death of the host (releases the cell contents into the water column). In addition to this feedback loop, the phytoplankton metal demand and thus the metal cycling via the microbial community are distinctly altered by changing temperatures. These complex interactions urge for further investigation to be able to unravel the cycling of bio-essential metals, especially iron, and assess how rapid warming affects the ecosystem. And this is exactly what we aim to do in our FePhyrus project!
12th of January - Sailors law
We started the cruise of well despite some obstacles we had to overcome in the beginning. The Titan sampling system needed some attention, but due to the very fast and useful response from our colleagues at NIOZ despite the fact they were enjoying Christmas holidays, meant this was swiftly dealt with. At the first station the rope used to deploy our CTD sampling system came off the winch winding system, due to bad weather water entered the air conditioning system of our analytical container and the temperature control for one of our incubators did not work at first. However, we managed to get everything fixed.
As the first three stations went well, and we had just managed to prepare everything, we were ready and all motivated for a night shift to get our samples and start our first bio-assay on the fourth station!
Then Rob came in and announced: "We have a situation – we are going back to Christchurch".
One very unfortunate crewmember has developed a medical issue and needs an operation as soon as possible. So, the Araon made a 180° turn, following the old sailors law, that a life on sea is priority over everything else. Therefore, instead of preparing for the next few stations, we started cleaning all our bottles for the transit time to Christchurch and then back to Antarctica (about 14 days altogether).
It is a strange situation on the ship now, as there are all those scientists, prepared for hard work, who now have not much to do – but we will not lose out good mood and we are all looking forward to coming back to Antarctica and continue our work there!
Right now we are taking some samples along the transit, by using the ships seawater taps, to collect information about changes in iron binding proteins, stress proteins and abundance of phytoplankton, viruses and bacteria.
4th of January - Christmas and New Years on the R/V Araon
Holidays at sea are unlike any other: they are a blend of cultures and traditions fueled by hard work and a rare beer (normally only reserved for a Saturday night). So far, we have experienced both Christmas and New Years Eve on board the R/V Araon. We had brought some Christmas decorations to give our labs a festive look. This worked out quite well for the biology lab but the trace metal lab was a bit harder to decorate, as we cannot introduce any contamination there. After long days sampling and working on various sampling instruments during the day, everybody is happy to have an excuse for a party.
On Christmas, we all gathered in the galley at 8:00pm, as the party was scheduled from 8:00-9:00pm. We arrived impressed by the spread of cheeses and fresh fruit – I’m particularly fond of the Korean Pears (‘Pae’) and Asahi beer (‘Maekju’). This was the first time all the staff scientists got to gather in a non-work setting, so it was fun to get to know everybody on a more personal level. Needless to say, the Christmas party didn’t finish at 9:00pm.
New Years Eve was similar, but with the introduction of a new Dutch tradition that I was pleasantly surprised by. ‘Oliebollen’, or basically fried Dutch doughnuts flavoured with raisins and shredded apples, are a New Years Eve tradition in the Netherlands. The crew were kind enough to let the trace metal team into the kitchen and cook up some of these desserts. I am definitely going to try and introduce this treat back in Canada!
Until next time,
Preparing for fieldwork in the Antarctic that almost never happened….
The 21th of December we boarded the research icebreaker Araon from the Korean Polar Research Institute where we will join the team led by Dr. Sang Hoon Lee for an expedition to the Amundsen Sea, Antarctica. Given this remote destination, we need to be sure we have prepared meticulously, everything needed will have to be brought and for our work, we need some special equipment.
DMT marine equipment came to the rescue: big THANK YOU!
Sampling for trace metals is no mean feat, the ship and machinery are made of metal and despite all the maintenance, there is always some rust due to the salty ocean water. The concentrations of metals in seawater however, are absolutely minuscule. In the case of iron (our main interest), the concentrations are equivalent to 1 paperclip dissolved in 40 billion liters of seawater, or 15 Olympic sized swimming pools! So one can imagine utmost care needs to be taken not to contaminate the samples, otherwise all we do is measuring how much iron we added to our sampled water, rather than the actual concentrations that we are interested in. In a later blog we will feature Titan, our trace metal clean sampling system that can take samples at different water depths in the ocean. Such a system needs to be deployed from the ship using a winch and a cable. The cable will be attached to Titan, and cannot be a steel cable as often used, this would contaminate our samples. Winches are present on the Araon and widely used in marine applications, so we did not expect this would pose a problem. However, time passed and one option after another was discounted for various reason, winch not powerful enough, in the right location, unable to deal with trace metal clean cable etc, etc. Until there was no option left and time was running out. Luckily at the very last minute Piet ter Schure and his team from DMT marine equipment came to the rescue. They worked around the clock and pulled off the impossible; they constructed a suitable winch in little more than a month and managed to deliver from their factory in Romania to Texel just before the transport of all gear had to leave for Christchurch in New Zealand. So a very big THANK YOU to the entire DMT team, without your efforts this expedition would have never happened!
Beside our equipment, we also needed to prepare many sample bottles for the collection of our seawater samples. Because of the extremely low concentrations of trace metals, this is quite a challenge. To be sure the plastic bottles do not contain any trace metals anymore, they need to be cleaned carefully using different cleaning steps. This means before a bottle is ready for use, we need to soak it in soap, rinse it five times with MiliQ water, soak it in hydrochloric acid, rinse it five times with MiliQ water and then fill it with a low concentration of nitric acid for storage. Considering that the first two steps takes at least half a week each, and knowing that we take hundreds or even thousands of bottles you can imagine this is a very time-consuming process, especially since only a limited amount of bottles fit in the heated soaking baths. Thus while iron can be the limiting factor for the Antarctic marine ecosystem, time was the limiting factor for us during preparation. Therefore we had to work for almost five weeks non-stop to get everything ready in time for shipping everything off. Of course the bottles are not the only things that we had to pack, also chemicals, all the consumables, etc., etc., needed to be ready and packed in time. This was in some cases very challenging due to unexpectedly long delivery times. Let’s just say we did not only have clothing in our checked in luggage flying here, but also some bottles, filters and even a heater J. Now, a few days before our departure we believe everything is packed and we are ready to start to explore the Amundsen Sea!