marine biology, oceanography, climate science, research, phd, fieldwork, university of oxford, carbon cycle, plankton Entry 04 February 20 2025 Escorts, sea survival and sea sickness Not a huge amount of science was done today - everyone gets a day of grace to adjust to the ship's movement, which leaves most feeling at least a little groggy - but let me tell you a little about the experience of leaving port. We headed out to the front deck where we had the optimum view. When you leave a big port like Rio you get a 'Pilot' - someone who knows the way and comes up to the bridge to guide you out. He came on around 0900 and we were off. We sailed past many of Rio’s landmarks – Christ the Redeemer, Sugarloaf mountain, and, breaching the mouth of Guanabara bay, we were out into the open ocean! It's quite an indescribable feeling really, knowing you won’t see land again for almost two months. The biggest excitement of the day, apart from three or four planning meetings, was the muster and lifeboat drill. This saw us all gathering in the hangar with our life vests and hard hats before filing up to the lifeboats. We all filed into the boats and sat while we were briefed on what would happen in the event! We spent the evening scheming in anticipation of science beginning in the next few days, and were treated to the most serene first night sunset. I sent a picture home to my supervisor, who replied ‘the happiest place on earth – the aft deck of a research ship’. I’m inclined to agree! back to diaries home page previous entry next entry

marine biology, oceanography, climate science, science communication, research, phd, fieldwork, university of oxford, carbon cycle, plankton Entry 03 February 19 2025 Containers, rigs and a fond farewell to Rio Our containers arrived which means not only do we have equipment but, in our case, we now have a lab. One of my most asked questions is whether the labs are built in to the ship and the answer is yes, many are, but some are also built into shipping containers which can be mixed and matched according to the needs of the specific expedition. That called for a 0500 start today, which was easy due to the excitement we all felt at finally getting going, and all hands on deck (now I understand where that phrase comes from!) to get everything unpacked, set up and tied down to enable us to sail the next morning. The first order of business was building filtering rigs - we have 8 in total with capacity to process 45 samples at a time, which might seem excessive but is absolutely necessary to do everything we want to do. Most of our rigs are towers connected to a vacuum pump, which uses negative pressure to draw the samples through the filters, but I also brought a peristaltic pump to filter my cartridge filters in-line, which required some clever DIY rigging to stay stable and easy to use. back to diaries home page We finished early and headed out for one final night in Rio - which was bittersweet as we'd come to miss it but we're absolutely ready to get going previous entry next entry

marine biology, oceanography, science communication, science journalism, research, phd, fieldwork, university of ocford, climate science, carbon cycle, plankton Entry 06 February 22 2025 4am espresso club, data analysis, argo floats and sunset birthday BBQs Today was an exciting day because it was the inaugural meeting of ‘espresso club’ – aka, Team Plankton meeting outside the ship’s coffee room at 0400 to begin the gradual shift to our 0300 starts (we still had a couple of time zones to go at this point). Making the most of the bonus hours in our day, we decided to take the opportunity to get our FIRST DATA – even if not from this cruise. The JC273 team had left us a couple of trays of chlorophylls in the hold, which we measured concentrations of. This felt like a momentous event, given how long we’d waited to start doing science. back to diaries home page Powered on by a gorgeous sunrise from the bridge and a run on the ship’s treadmill (god bless dynamic positioning), we spent the afternoon in our RN container (henceforth named and referred to as ‘Steve’) making up nutrient spikes for our amendment experiments. In the afternoon we deployed a further two Argo floats, before the crew spoiled us with an incredible spread at a barbeque on the aft deck – complete with a spectacular cake to celebrate Marika’s birthday. previous entry next entry

marine biology, oceanography, climate science, science communication, science journalism, research, phd, fieldwork, university of oxford, carbon cycle, plankton Entry 10 February 27 2025 Arriving at the mid-atlantic ridge, phytoplankton and the carbon cycle Today was a transit day to our ‘ridge’ site – almost time to test our theory of increased productivity on the mid-Atlantic ridge! We used the afternoon to host another mini-conference of science talks – and today was my turn to present. It was a really supportive and curious atmosphere and, though it was only a 10/15 minute talk, sparked much discussion afterwards. While we’re here, I’ll take the opportunity to tell you a little about my PhD. My focus is marine phytoplankton and their role in the carbon cycle. Phytoplankton are key players in the biological pump, that is, the flow of carbon from the air, to our oceans, to the deep ocean. This is a key process as it locks carbon out of our atmosphere, reducing the effect of CO2 in warming our planet. However, as our planet is warming and the ocean is absorbing that heat, its surface is increasing in temperature. This causes an increase in the temperature gradient between the surface, low nutrient, high plankton layers, and the lower, high nutrient, low plankton layer. The plankton in the surface rely on mixing between these layers to get the nutrients they need to grow. As the stratification of the ocean increases, there is less mixing, and less nutrients are delivered to the surface. We think this will alter the community structure of phytoplankton in the surface ocean, as a result altering the capacity of the ocean to absorb carbon dioxide. back to diaries home page One theory is that this will shift phytoplankton communities towards smaller phytoplankton, which is where my PhD comes in. With my fieldwork and lab-based study, I am seeking to understand a) how is community structure of phytoplankton in the surface ocean likely to change in response to changing nutrient supply?, b) how and why are picoeukaryotes (particularly a few groups) so well adapted to these conditions (physiological and biochemical mechanisms)? and c) what does photosynthesis and carbon cycling really look like in these organisms - and can we optimise this? As part of this, I’m also looking at specifically-adapted communities, such as those in the deep chlorophyll maxima, and the effect of different nutrient and light regimes, such as those on and off the mid-Atlantic ridge. previous entry next entry

marine biology, oceanography, science communication, research, phd, fieldwork, university of oxford, climate science, carbon cycle, plankton Entry 01 February 11 2025 Come along with us on our trip from Rio to Namibia via the mid-Atlantic ridge looking at the role microscopic photosynthesisers play in absorbing carbon from our atmosphere and storing it away in the ocean depths Hello! If you're new here, I'm Ari, a PhD student at the University of Oxford, an avid science communicator and video reporter/producer for new scientist . I'm about to embark on my second research cruise, for the expedition that will provide me with the bulk of field-data for my DPhil (that's the Oxford term for PhD). Before joining the ship, I spent an incredible week in the Amazon Rainforest - I couldn’t miss the opportunity whilst in Brazil! But I'm now on my way to join the ship and my team in Rio de Janeiro, from where we will sail to Walvis Bay, Nambia, over 47 days at sea. The cruise, aboard the Royal Research Ship James Cook, is sailing under project CarTRidge . The overarching project is looking into the role the mid-Atlantic ridge plays in carbon export. I'm part of Team Plankton, looking at the role these microscopic photosynthesisers play in absorbing carbon from our atmosphere and storing it away in the ocean depths. We are a team of four: Professor Alex Poulton (Herriot-Watt University), Dr Ben Fisher (Herriot-Watt University) and Frieda Schlegel (The Marine Biological Association/Southampton University) ... and me! back to diaries home page I'm going to be sharing about my own experience of being a PhD student at sea - the ups and downs, night shifts and hours at the filtering rig. If you're interested in more information about the cruise at large, our chief scientist Professor Jonathan Sharples is keeping a blog I'd highly recommend a read. previous entry next entry

marine biology, oceanography, science communication, climate science, research, phd, fieldwork, university of oxford, carbon cycle, plankton Entry 02 February 13 2025 CTD, fish and a vast array of data Our supply containers have been delayed so, while we wait, let me tell you about the different experiments we have planned, and what sort of data we hope to get from them. There are two main types of experiments that correlate with sampling methods; those from the CTD, and those from the Tow-Fish. The CTD, a large Rosette device, has 24 sampling bottles and can go down to a depth of 6km before ascending and collecting samples from different depths. The CTD also measures the physical parameters in terms of water conductivity, temperature and depth (from where it gets its name). The Tow-Fish is a much smaller deployment that is suspended over the side of the ship and pumps water from the surface straight into our metal-free container. The Fish collects water from a distance away from the ship so as not to be contaminated by the ship itself. The samples it collects are trace-metal free and so when looking at things like Iron (a trace metal in seawater) there is no interference from the ship environment. The CTD we'll allows us to look at depth. An important concept in this research is the Deep Chlorophyll Maxima, essentially a region around 100m below the surface of the ocean where light is so low (around 1% of surface irradiance) that the phytoplankton community there massively upregulates the concentration of chlorophyll (the green pigment in plants and algae) to allow them to continue to photosynthesise. We are interested in understanding what that community is and what is going on on a genetic level to observe what genes are switched on or off under what conditions. The samples collected by the Tow-Fish will enable us to look at nutrient limitation. By adding macro- and micro-nutrients to the natural community and incubating them for a period of time we can observe the community response in terms of how the community changes, and what type of genetic responses individual phytoplankton have. In addition to the genetic analysis, we'll be measuring and sampling for many other things: chlorophyll, size-fractionated chlorophyll, scanning electron microscopy, flow cytometry, flow-cam, and more. This will combine to provide a more complete dataset to help understand the current status of the ocean. Shift patterns will not be set but generally samples need to be taken before the sunrises at dawn. This means that most days will begin at 0300 hours. back to diaries home page previous entry next entry