All change: half time in the Celtic Sea

Alex Poulton, National Oceanography Centre

This morning marked a key placeholder in this cruise: a boat transfer and change of scientists. After half a day's steam we arrived in Falmouth bay, although the ever present sea fog meant that we could have been anywhere from the depths of the South Atlantic to the icy waters of the Arctic. Out of the fog came our three new recruits: Angie Milne, Matthew Fishwick and Elaine Mitchell. 

One of the new arrivals (Matthew Fishwick) climbing up the ladder from the launch. Photo: Chata Seguro.

Like half time in a football match, though without the orange quarters and deep heat, our three new recruits were soon on the pitch – after a brave climb up the ladder and onto the deck of the RRS Discovery. This was a straight like for like substitution for us: two new iron chemists to replace the two leaving and a new bacterial ecologist to replace the departing one. After a quick hello and bye from the new recruits to those getting off, the three leaving climbed down the ladder into the waiting launch and then disappeared off into the mist.

Farewell to those departing. Photo: Chata Seguro.

Before the new team members had a chance of relaxation they were informed that sampling would begin again in 12 hours - they had just half a day to orientate themselves on the ship (i.e. find their bed, their lab coat and the galley) before joining the rest of the team for a full night and day of sampling, firm in the knowledge that there was just over two more weeks to the final whistle.    

OMG - Glider glee!

Dr Charlotte Williams, Marine Physics and Ocean Climate, National Oceanography Centre

Today at our main sampling site (CANDYFLOSS) we are deploying our sixth and final ocean glider! Ocean gliders are robots which ‘glide’ up and down in the water whilst taking measurements of temperature, salinity, chlorophyll and oxygen (plus a few more things), and these are what I work with. They send their data back to us when they surface via satellite. The amazing thing about gliders is that we can see the data they are collecting from anywhere with an internet connection as soon as they surface (every 30 mins or so in 100m of water). In fact as I am writing this blog I am checking the data that is coming in from the 4 gliders we have out at the moment! This has been useful for our research cruise as we are trying to catch and sample the ‘spring bloom’. This is where light and nutrient requirements for phytoplankton in the surface become just right in spring, and so we see a bloom in phytoplankton growth. This can be observed by an increase in chlorophyll, which the gliders measure.  

The ‘OMG’ glider being ballasted in the tank. Photo: Jose Lozano.

Sam Ward, the glider engineer from National Marine Facilities, has been working very hard to ensure that the gliders are ready for the water. This includes ‘ballasting’ them in a big tank on the back deck. The gliders don’t have a propeller, they move up and down in the water by changing their buoyancy, which is much less power hungry. Sam has to check how buoyant the gliders are in the seawater that they are being deployed in, as the density of seawater changes according to its temperature and salinity. There will be more to come on how the gliders work in Sam’s future blog! The last glider being deployed today is particularly exciting as this is an Ocean Microstructure Glider (OMG). This glider measures all of the things listed above, but also measures the turbulent kinetic energy dissipation, which is a kind of fancy term for turbulence and mixing. Being able to estimate the mixing in the shelf seas is important because we can then estimate how nutrients and carbon move around.  We will have to see if the dolphins return to see the OMG glider!  

Another glider about to dive under the waves. Photo: Jose Lozano

Spring has sprung - here comes the bloom

Alex Poulton, National Oceanography Centre

After two weeks in the Celtic Sea we are seeing clear signs that the spring bloom has truly begun - nutrients are declining whilst levels of the pigment chlorophyll, used by phytoplankton for photosynthesis, are steadily rising. 

Just how green the water is at present (slightly cheating as this is a pigment extract rather than seawater). Photo: Chata Seguro.

The bloom appears to be patchy across the Celtic Sea; from the shelf edge where the bloom has not started to show strongly yet, to the central Celtic Sea (where our Candyfloss site is) where small phytoplankton are actively growing, to the northern Celtic Sea where we saw huge diatoms (images below) - a type of phytoplankton which often characterises blooms and productive waters - which were at least a hundred times larger than anything we have seen so far. 

Diatoms and zooplankton seen under the microscope. Photo: Chata Seguro.

A close up of one of the large diatoms we saw in the NE Celtic Sea. Photo: Chata Seguro. 

As the nutrient levels continue to decline we are keen to see what happens within the phytoplankton community: will there be a clear progression from large cells to smaller cells which needs less nutrients for growth, will the diatoms be succeeded by another phytoplankton group? How these changes are reflected in the rest of the ecosystem is a key question we will address over the next two weeks. For example, how will changes in which type of phytoplankton is present influence the different nutrients needed for their growth (nitrogen, phosphorus, silica), and will we see changes in the dominant types of zooplankton (tiny animals that eat the phytoplankton) across the Celtic Sea.

The ever present fog viewed from the bow of the RRS Discovery. Photo: Chata Seguro.

Though the bloom has arrived, we have lost the sun - a dense sea fog has descended on us over the last few days which means we can only see a hundred to two hundred metres in any direction (see image). The eerie silence that this has brought to the ship is broken up at regular intervals by the ear shattering sound of the ships horn announcing our presence. If the spring bloom didn’t know we were here before, you can be sure that it does now.

The Mysterious NMF Fellows on DY029

Jon Short, National Marine Facilities Sea Systems, National Oceanography Centre

In other blog posts, both from this cruise and from previous cruises in the SSB programme, there have been references to the National Marine Facilities technicians but few added details. So just who are these mysterious fellows and what do they do?

National Marine Facilities Sea Systems (NMFSS) is the organisation who manage the RRS James Cook and the RRS Discovery and the National Marine Equipment Pool as well as providing technicians and engineers providing specialist support to NERC research cruises on both the NMFSS ships and other vessels.

Jon Short preparing the trace metal rosette and Niskin sampling bottles. Photo: Callum Whyte.

There are seven technicians from NMFSS on board Discovery for DY029; Rob (who looks after the mooring deployments and instrumentation), Alan (our mechanical engineer who looks after equipment ranging from deck winches to the machine that produces liquid nitrogen at -300^oC), Jon (our IT expert, who makes sure that all of the vital data, from numerous instruments, is logged and recorded), Sam (who prepares and deploys the autonomous gliders) Robin and Colin (who are learning how to operate and maintain the two CTD systems on board) and me, another Jon (also looking after the CTD systems and, very loosely, in charge of the team).

The NMF team preparing to deploy a mooring. Photo: Alex Poulton.

For each cruise supported by NMFSS the preparation starts at least six months before the sail date when we meet with the senior scientists involved and discuss with them what they want to achieve and which pieces of equipment from the pool are best suited to gather the data. This equipment is then prepared for use on the required research cruise. For DY029 this involved the design of moorings and the procurement of hardware for these moorings, payloads for the autonomous gliders to be identified and fitted, laboratory containers to be fitted out to the specification of the scientists involved and instruments, fitted to the CTD frame and on the moorings, to be calibrated to very precise standards.

The NMF team and deck crew recovering a glider. Photo: Callum Whyte.

Once this is all complete the technical team and the ship's crew "mobilise" the vessel. This involves loading all of the equipment required (including everything the scientists bring), installing it on board and commissioning it for use. After the ship sails we provide 24 hour support, operating, maintaining and deploying equipment and making sure the scientific team have everything they need for a successful cruise.

The NMF team preparing the anchor chains for the moorings. Photo: Callum Whyte.

The breath of the ocean

My name is Jose Lozano and I am a PhD student from the University of Vigo, Spain. In this cruise (DY029), I work with  Elena Garcia, post-doc at the University of East Anglia, taking samples and doing  measurements of oxygen (O₂) respiration in the Celtic Sea (Candyfloss) by using different methods, Optodes (optical sensor devices, which is designed to measure absolute oxygen concentration and % saturation), Electron Transport System and Winkler (a test used to determine the concentration of dissolved oxygen in water samples).

Net community production (NCP) is a measure of the net amount of carbon removed from the atmosphere, which represents the difference between Gross Primary Production (carried out by phytoplankton through the photosynthesis) and Dark Community Respiration (from both phyto and zooplankton). Plankton found in the world’s oceans are crucial to much of life on Earth. They are the foundation of the bountiful marine food web, produce half the world’s oxygen and suck up harmful carbon dioxide.  It is therefore vital for scientists to closely observe the oceanographic and biological variables related with these little buoyant organisms, temperature, nutrient content, light extinction or partial pressure existing in the water column.

During the cruise we have very busy schedules, not only the scientists but also the crew and  the technicians. They all work constantly, making the practice of science much easier, by cleaning, cooking, creating tools, or fixing devices. We, the scientists, couldn't make it without their support.

Dolphins, Photo: Jose Lozano

When you spend 24 hours a day in an oceanographic vessel, even in hours of rest, you feel very tempted to go on deck to chill out and breathe the fresh air at the stern. In a good day you can feel the ocean breathing gently and musically through the waves, the cool wind blowing on your face, you can observe the wildlife, the terns and the gannets flying over your head and families of common dolphins jumping playful just few meters away from the vessel. You can even see some land animals, such as owls, garden birds or little spiders, which are travelling with us on the ship. All these organisms, from the smallest diatom to the biggest marine mammal, breathe oxygen (though in the case of archaea or bacteria, other molecules may be used) in order to obtain energy from organic matter, so to be able to keep going.
        

Sandwich tern. Photo: Jose Lozano

DY029 Fe transect trilogy: The return of the Team Iron

Metal contamination free science on a metal ship: trace metal saga

Main characters:  The Incredible Team Iron

Protagonists:

Maeve Lohan (University of Plymouth)

Antony Birchill (University of Plymouth)

Dagmara Rusiecka (University of Southampton/Geomar, Kiel)

Amber Annett (University of Edinburgh)

Antagonists:

Metal contamination (Everywhere)

 . / . 

 DY029 Fe transect trilogy by Dagmara Rusiecka (University of Southampton/Geomar, Kiel): The return of the Team Iron 

It’s been less than four months since DY018 and ‘Team Iron’ is back on board RRS Discovery waiting with excitement for the first cast of the first iron transect…

Encouraging message from the Team Iron fan club onboard. Photo by Chata

April the 7^th, 11PM, kick off: Team Iron is all dressed up in clean white Tyvek suits and white mop hats rushing around in the clean sampling lab. 24 grey bottles designed specifically for the trace metal sampling returned from 2500m and with gloved taps were very quickly transferred from the deck to the clean lab to minimize the risk of metal contamination. Now, they’re racked on the wall, safe, secured and ready for a solid 4 hour sampling session. Team Iron wearing ‘dirty’ gloves is tackling through sample bottles for other scientists; DOM (dissolved organic matter), SPM (suspended particulate matter), alkalinity, flow cytometry, chlorophyll a, oxygen, salinity. Finally, it’s time for the ‘clean’ gloves and the ‘clean’ samples!

In meantime, outside of the clean lab, Amber Annett is already waiting for the stainless steel rosette to return on deck with 480L of seawater just for Ra (Radium) isotope measurements at only a few depths! In plastic cubic containers she’s carrying 20L of seawater one by one on her shoulder to her container. She’s not only strong but also a lucky girl. No need to worry about the metal contamination but hey, she needs liters of seawater to detect the short-lived Ra 224 isotope! Therefore, the rosette is deployed again for another round and more water for Amber.

Team Iron in the zone of discussing results from DY018. Photo by Jose Lorenzo

1AM: All geared up with clean sampling clothing. Team Iron is tackling through ‘clean’ sample bottles.  5 liters for chromium isotopes, 1 liter for iron isotopes, 500 ml for copper speciation ……. It’s time for their own samples. 250 ml for iron speciation, one 125ml bottle for trace metals and one 125ml bottle for iron.

3 AM: Team Iron is packing samples from the first cast whilst the ship is already at the next station and the crew is ready for the next cast. “Here we go again guys! 6 stations to go!” and the process is starting all over again.

Rare and short appearance of 'Rosie' the trace metal clean titanium rosette with bottles on deck. Still with gloved taps, almost ready for the deployment. Photo by Dagmara Rusiecka

Coming up soon:

Volume two: The Two transects

Volume three: The Fellowship of the Iron: Final transect

So why do we do what we do?

As some of you may know, iron is an essential micronutrient to marine organisms present at very low concentration. It influences phytoplankton productivity, community structure and ecosystems and is a limiting factor on primary production in some regions. Our aim is to capture the mechanisms of iron off-shore transport to the open ocean that currently are unknown.

Three, two, one … go! .... Welcome to the Central Celtic Sea!

Chata Seguro, PhD student,  University of East Anglia

It is 4^th of April, 10 am and we have just finished almost all of the work for the day. Many of the SSB (Shelf Sea Biochemistry) scientists had a very early morning, rising at 2:30am for the first pre-dawn CTD of the cruise. 

Why we are doing all the work so early in the morning? 

Because we need to catch the phytoplankton while they are not fully active, so that we can start our measurements and experiments early and follow their activity throughout the day. There was a bit  of confusion and “moving in slow motion" at the first CTD, but  the usual pre-dawn rhythm quickly set in, followed by two glider deployments, and then another CTD after that. 

The last rays of sunlight disappear behind the clouds the night before the first pre-dawn.
Sunset was quickly followed by many scientists disappearing as well to rest a few hours
 before the early CTD. Photo: Chata Seguro

The deployment of the sea-gliders later in the morning, appeared to act as a big colourful toy for the local dolphins as a large school of them, including baby dolphins, appeared on the horizon just after the glider deployment. They remained around during breakfast, but unfortunately, I did not manage to take any photos. Soon after breakfast, I decided to try a  trick that worked well one night during the cruise last November - to whistle to them! And .... they came! But once the large yellow toy disappeared under the waves, the dolphins  couldn't find anything interesting to play with, so they left as fast as they came. To my disappointment, no photos, but still great to see them coming after just a few whistles! It is thanks to Charlotte Williams, a physical oceanographer, that I am able to post a picture of dolphins playing around during the glider deployment (picture below)

 

Dophins playing around the Seaglider and ship. Photo by: Charlotte Williams.

Dophins playing around the RRS Discovery. Photo by: Charlotte Williams.

Apart from seeing the playful dolphins, it is always great to see scientists in action. James Fox and myself (both PhD students) enjoy comparing how our daily peaks of photosynthesis and oxygen production match on our instruments, which are set up next to one another in the main laboratory of the ship.

A few minutes ago, there was another call for another CTD and scientists were already queuing to sample the CTD. Suddenly, Robin (our NMF technician) shouted: "three, two, one … go!" It is the Central Celtic Sea and we were ready!