New adventures

By Stefan Gary

The last several days have been a buzz of activity at the King George V docks in Glasgow; the RRS Discovery arrived to unload people and equipment after the end of the Extended Ellett Line cruise and take on new people and equipment for the first of this year’s UK OSNAP cruises.

This year’s Extended Ellett Line went well.  We completed all the work we set out to do, didn’t have any major interruptions to our work, and even had time to collect even more data.  Many thanks to the crew of the Discovery; these excellent results hinged on the close community, great conditions for life aboard, and clear communication between the crew and scientists.  As we approached land, we were greeted by the sight of whales and dolphins feeding at Stanton Banks and had the opportunity to take a photo of the science team enjoying the sun on the Forecastle Deck.

In the coming months we will carefully analyze our last samples, cross check the data, produce a cruise report, and write papers.  One preliminary result is that the surface waters of the Extended Ellett Line are slightly cooler and less salty than previous years.  Year-to-year changes in temperature and salinity occur as the currents in this region shift position and/or strength with possible impacts on the creatures that live here and maybe even the local climate.

One way to see both the extent of the data collected as well as the interaction between the atmosphere, the ocean, and life in the ocean is the oxygen we measured below the track of the ship from Iceland (left) to Scotland (right); each black dot is a water sample (image below).  The low oxygen at mid depths is created through the interplay between deep mixing caused by winter storms “renewing” the oxygen at depth and the breathing (consumption) of oxygen by animals.

The data collected during the Extended Ellett Line is an exceptionally detailed snapshot of the ocean.  The ocean is ever flowing and changing so another observational tactic is to place moorings at key locations in the ocean and record data over the course of a year or more.  Servicing moorings in the water is the goal of the next cruise of the Discovery – stay tuned!

Image credits: Winnie Courtene-Jones and Rich Abell.

EEL2016 science team

EEL2016 oxygen section

Listening for Sperm Whales in the North Atlantic

By Leah Trigg

Sperm whales are the largest of the toothed whales and can grow up to 18 m in length. Their most prominent feature is their head, which makes up approximately one third of their total size. They live in stable mother-led families and are thought to live up to seventy years. They are famous in the whale world for being particularly deep divers – venturing into the depths for their favourite food, the Giant Squid.

Recently, sperm whales have been raised from the deep and brought to the forefront of human consciousness by the sad sight of these ocean giants ailing on the beaches of the North Sea. Our dismay and inability to understand what had brought these magnificent animals to an untimely end serves to highlight how little we still know about life in the ocean. Observing the surface of the ocean leads to only rudimentary insights into how its inhabitants live. We are often left to wonder about what lies beneath the waves. Or are we…?

If you have been reading the blog you probably already know that, among many other oceanographic pursuits, we have spent the last three weeks using underwater sound to understand the number and distribution of sperm whales in the North Atlantic. We have been towing a hydrophone, which gives us a rare window into the ocean deep and has allowed us to record some amazing examples of sperm whale clicks. Take a listen for yourself here. The sperm whale makes regular clicks that sound very much like the blows of a hammer. If you listen carefully you can also hear the regular slap of the ship’s propeller.

The underwater world is one of sound. Very little light penetrates into the depths of the ocean making it difficult for the organisms that live there to rely on sight. Sound, however, propagates very efficiently in seawater and sperm whales have mastered the use of sound for vital life processes such as communication, navigation and prey detection. We can use the sounds produced by sperm whales to count the number of individual whales, pin point their location relative to the ship and even estimate their size.

Initial observations suggest that we have recorded the most sperm whale clicks between the shelf break and a seamount called Anton Dohrn. It will be interesting to put together our final data and discover if this really is the case. Not surprisingly, this observation gives rise to important questions for the future such as, what is it that makes this area particularly attractive to sperm whales.

So while the work continues to unravel the mysteries that the sperm whale and its fellow oceanic inhabitants hold close, next time you find yourself gazing out to sea, try to imagine the bustling oceanic metropolis that is out of sight and just what it might sound like…


Rare earth Ellettments

By Emily Hill

I’m aboard the 2016 Extended Ellett Line collecting water samples for trace metal analysis, specifically the rare earth elements. This sampling was also done last year and formed my final year project at SAMS. We’re building on that work this year to assess the applicability of rare earth elements as water mass tracers. The Extended Ellett Line provides a good test bed for this research as the different water types of this area, also known as water masses, are well documented. These samples will help us understand how rare earth elements can be used for reconstructing the ocean currents of the past.

After I take my samples from the bottles on the CTD, I need to filter and acidify them on the ship. Then, the samples will be analysed back at SAMS.
It’s pretty straight forward providing you’ve got everything you need! We made sure this year that we have everything in abundance, 6 boxes of gloves, 200 filters etc. At some stations I am also collecting 10L samples for analysis, which takes quite a long time.

We’ve got a great team on board this year and everyone seems to be in good spirits and getting along with what needs to be done. When I’m not sampling my own stations, I help out with the CTD casts where I can and reading books from the extensive library on board. I’ve also learnt some new card games and we often play some rather interesting board games too!

Sights at sea

By Liz Comer

The views from Discovery have been plentiful over the last two weeks, consisting of a very muddy back deck, rocks poking out of the water, many birds and a passing of our very own RRS James Cook on its steam back to Southampton. This has provided us with much entertainment and excitement.

Over the last two days the Benthic team have been deploying bottom trawling sleds that collect muddy sediment from around 2000 m depth. When it gets hauled onto the back deck the muddy sediment that is caught in the nets needs to be transferred into buckets, ready for filtering. The team will then analyse the creatures that are living on the sea bed (see previous blog entries, below).

Birds have been the most abundant type of wildlife that we have seen, particularly fulmers. The fulmers seem to think we are a fishing boat and hang around in large numbers around the back deck. They haven’t seemed to cotton on to the fact that we are only pulling up mud and water samples from the ocean. I think these, along with the gannets, have been a favourite for everyone on board. I have learnt that the fulmers can be distinguished by their black nostrils, gliding close to the waves and the gannets have an obviously yellow head, long wings with black tips. Leaving Scotland some of my fellow scientist spotted Puffins and I saw an arctic skewer when we were nearing Iceland (photo in previous blog). We have passed Rockall which is a large rock sticking poking out the water, however, it has a covering of bird droppings on the top making it look like an ice frosted cake or a snowy mountain.

Microplastics: Small things causing big problems

By Winnie Courtene-Jones

Pictures: Winnie Courtene-Jones and Peter Lamont

Microplastics are small fragments of plastic, typically smaller than 5mm in size. They are found in different shapes and colours (pictures below). Microplastics occur as larger plastics fragment into ever smaller pieces or are intentionally manufactured to be small, for example in some exfolianting washes and toothpastes. Plastic is a durable material so when it enters the environment it persists and doesn’t just go away.

Microplastics can be found in vast quantities in the world’s oceans; in some surface waters microplastics can outnumber plankton! Plankton are the small organisms that support life in our oceans. This poses a threat to marine animals which can accidentally eat microplastics. Once eaten by an animal, microplastics can be retained inside that animal and are passed up the food chain and may ultimately reach humans.

The deep sea has long been considered a pristine environment, an area which is ‘out of sight out of mind’. However the deep sea faces a number of human impacts, including plastic and microplastic pollution. Have microplastics made it down into the deep sea? Have they been accidentally eaten by the animals living there? How do the amounts of microplastics eaten vary between different types of animals? For example, brittle stars are scavengers but bivalves filter the water to extract food.

We hope to start addressing these questions using the creatures collected during this research trip (see earlier post about collecting samples from the deep sea). The oceanographic data from the Extended Ellett Line and other measurements in the North Atlantic will also help to assess how long it takes for microplastics to make it down to the deep sea floor and how the ocean currents distribute microplastics.

Bobbing along at the bottom of the sea

By Martin Foley

The Extended Ellett Line, our cruise track, runs over Rockall Trough, a cradle of deep sea biology. In Rockall Trough, we go to a place about 2200m deep, just off Anton Dohrn seamount, named Station M (pictured). By reaching down and bringing a load of sediment up, we can look at the animals that live at the bottom and see how their numbers change in time. It is not a static environment by any stretch of the imagination!

As I write this, I am sitting in the belly of the RRS Discovery half-way through a three week cruise and our epibenthic sleds are strapped to the deck and ready to be deployed when we reach Station M. The sled is basically a metal cage with a closable door in which we lash a net to the inside. It is is lowered off the back of the ship until it reaches the bottom of the Trough and dragged for around 2km along the seabed.

As it skims the bottom, the sled disturbs the top layer (the epi in epibenthic) of the sediment and collects the creatures that live there. All manner of beasts live there, from bivalve molluscs to tube dwelling crustaceans, polychaete worms to tiny starfish, and bundles of nematode worms. These are all then hauled up on deck, sediment and all, and are sieved.

Everything bigger than 4mm is classed as megafauna, this gets caught in the first sieve; next comes macrofauna, everything between 0.5 and 4mm; and then finally the meiofauna, anything that has eluded the first two sieves but cant squeeze through a 420m gap.

Finally, the samples get fixed in formalin to stop the soft tissue from turning to mush and they are ready for their journey back to dry land where it is sifted and sorted into taxonomic groups by anyone up to the challenge.

Julian Daze

By Stacey Felgate

Photo credit: Liz Comer

We are a week into the cruise, and the newbie sailors have just about got a handle on things! Some things were pretty easy to acclimatise to (being constantly fed seems to suit us quite well) but others are still a bit of a challenge, perhaps best demonstrated when someone asked the question “who is Julian Day?”

Considering that timing is everything on a cruise, it is remarkably tricky to get the hang of. We left Scotland in BST. 3 days in, our mobile phones (and defacto alarm clocks) automatically switched to Iceland time (UTC) in the middle of the night, but ship’s time stuck with Scotland to avoid any confusion and almost every first timer missed breakfast in true ironic fashion. Fast forward a few hours, and we were introduced to the Julian Day.

Julian days run numerically on a 365 day cycle, and are what all ETAs are given in on-board. Day 1 of the cruise corresponded to day 158 in the Julian calendar, and so today is day 167. It is a decimalised system, and so times are quoted numerically: 167.5 would equate to 12PM today, for example. Except it doesn’t, because Julian days are synced with UTC, not BST, and so you have to subtract an hour, making it 11AM. Still with me? Good.

On which note, I may or may not be due for sampling on deck… wish me luck!

Under pressure

By Emma Slater

Photo credit: Ashlie McIvor

During the Extended Ellett line cruise, it is a tradition to attach polystyrene cups to the CTD frame on the deepest cast. Our 19th CTD was going to be the deepest cast so drawing nautical themes on polystyrene cups could commence. The cast was going to drop down to ~2700 m which is about 270 times surface air pressure.

The effect on the polystyrene cups was quite staggering. What makes polystyrene useful is that it is filled with air pockets. This makes it a good insulator, but when put under such high pressure those air pockets are forced out giving us the miniaturised versions you see in the photos. You’ll also notice from one of the photographs how we’ve been doing our laundry…

Unfortunately, during the upcast, the computer in the main lab had trouble firing the Niskin bottles. Once on deck we realised none of the Niskins had closed and so no sampling could be done. After further investigation, the mechanism that releases the bottle endcaps and allows the bottles to close had to be completely replaced for the next station. Thanks to all the preparation ahead of the cruise, we had a spare!

Going, going, gone…

By Robert King

Picture credit: Emma Slater

In the early hours of this morning, we dropped some expensive kit overboard. Not to worry: we meant to. This event was the deployment of two Argo floats. These are autonomous ocean profilers which have been deployed all over the world’s oceans as part of an international effort to measure below the surface of the global ocean.

The photograph below shows one of the two floats being lowered carefully into the water and then floating away as we steam towards our next CTD station. This float should now spend the next 3 years or so (more if we’re lucky) making measurements of temperature and salinity as it travels where ever the currents take it.

Much like the CTD measurements we have been making, Argo floats are used to measure the temperature and salinity of the ocean sub-surface. They spend most of their time waiting at a depth of around 1000 m, then every 10 days they first descend to 2000 m before measuring temperature and salinity on their way back toward the surface. Once at the surface, they send data back via satellite and drop back down again to 1000 m.

By ‘parking’ at 1000 m, the Argo float can avoid the stronger surface currents and so remain closer to where it was deployed. This allows the global array of Argo floats to better sample the whole ocean. If they were allowed to drift freely at the surface, we would likely end up with uneven coverage.

Today there are around 3900 Argo floats distributed over all the Earth’s oceans. The observations from this array are used by scientists in many countries. For instance, at the Met Office we ‘assimilate’ the observations of temperature and salinity into our operational ocean forecasting models. These in turn are used in a number of applications, including ship routing, offshore operations, search and rescue, and fisheries management. They are also used in climate research to monitor large-scale changes in the ocean.

Unlike the CTD measurements described by Liz yesterday, we won’t be pulling the Argo floats back on-board. This plunge into the ocean wakes them up as they start their missions.

A day in the life of a blob of ocean water

By Liz Comer

There was once a blob of water milling around in the ocean minding its own business until a bunch of scientists came along in a research vessel (us on Discovery) and sampled it. To sample water, scientists lower instruments and bottles over the side on a rosette frame (as shown in the picture below). The instruments contain sensors to measure pressure, temperature, salinity, oxygen, the available light for algae to live in the ocean and the murkiness and colour of the water. The water flows through these sensors (red arrow in picture) or is trapped in the bottles (yellow arrow in picture). Last year a fish even managed to get stuck in one of the sensors which offset the measurements. These two forms of sampling are then analysed separately; the sensor measurements are processed on a computer and bottle samples in lab based instruments. The images below show these lab instruments; imagine the confusion in setting up the nutrient analyser! The salinity is analysed in a separate room, nicknamed the salt mine, due to the need for a stable temperature for the instruments to work reliably.

The two separate measurement streams, bottles and sensors, are then compared. The result of this process is a calibration where the sensor measurements are corrected using the bottle sample measurements. With this step complete, the blob of ocean water has been observed and its properties are ready to be recorded in a database back on dry land.