2018 Cruise - JC165

JC165 returns to Southampton!

As we head from the Porcupine Abyssal Plain to Southampton the seas turn from a crystal blue to ever increasing shades of green. The seas calm and our pace changes from going from station to station over to cleaning, organizing, packing and thinking of what we will do next time.

One of my main areas of interest is tracing the influence of climate through the upper ocean. This includes production of algae and plankton at the sun-lit surface and the sinking of some of this carbon-rich material (marine snow) through the water column and onto the seafloor. Because this sinking marine snow is a key food source for life on the seafloor, climate variation can have a close connection to abyssal marine life even though it’s separated from the atmosphere by three miles of cold dark water.

The PAP- Sustained Observatory systems have one of the most comprehensive sets of tools in the world to address this climate to seafloor connection. On this research cruise we have been able to take extensive sets of seafloor samples and photographs that will be used to make some of the most detailed estimates of the amount of life found on the abyssal seafloor. Accurate estimates of the sinking marine snow and the mass of seafloor life help track the stock and flow of carbon in the ocean. Estimates of how climate change might alter seafloor life in the Northeast Atlantic suggest that the mass of life at the PAP-SO could decrease by nearly 50% in a century (https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.13680). So making accurate estimates now is critical to understanding how this globally important change might occur.

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The effort is only possible because of the efforts of the officers, crew, technical support and science teams working together and this trip had some unusual challenges. These included servicing one of the tallest moorings in the world as well as running one of the deepest trawl tows still done today. Thanks very much to them, only some of whom are pictured below.

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So now it’s back to our labs, workshops and offices to look at what we have found and what the observatory will tell us as it reports data back to shore throughout the year (http://projects.noc.ac.uk/pap/data). And back to life ashore with family, friends and summer coming right along.

 

Written by Henry Ruhl.

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2018 Cruise - JC165

RRS James Cook Ship Systems

I am regularly asked “How did you go from oceanography research to becoming an IT technician?” … well. Let me explain. As one of the Scientific Ship Systems tech’s on the James Cook I don’t just look after computers. We support all of the scientific instrumentation that is physically fitted to the ship, and all the infrastructure to enable data acquisition, storage and transmission.

Each deployment to the sea bed is reliant on instruments that we support. I can tell you that the current depth is 4728 metres (m). This is provided by two echo sounders which are built into the hull; one is a single beam, and the other is a multibeam which we use for sea floor mapping. The surface water temperature is 12.8 °C and salinity is 35.54, as measured by instruments in the underway sampling system. The air temperature is 11.4 °C and the wind speed is 19.8 knots. These measurements come from the meteorological instruments that we look after on the bow of the ship.

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Figure 1. The screen bank of RRS James Cook

At the moment the megacore is on its way to the sea bed and is currently at a depth of 1755 m and is descending at a rate of 50 m per min. On the core frame is a USBL beacon so we can provide high accuracy positioning of the instrument, knowing exactly where the sediment samples came from.

We record all these data and transmit this information all over the ship which means that although I’m in my cabin, I know what’s going on by checking the intranet live data feed. Some of the data is transmitted off the ship, feeding into weather and ocean forecasting models. Our data feeds support so many other operations onboard, such as the CTD and HyBIS.

All the data is synchronised into a file storage system and made accessible through the internal network for the scientists to work with. The network brings us back to IT because computers are a central part in data acquisition and processing. In between the computers and the instruments are several kilometres of wiring that we have to navigate; if an instrument isn’t getting the data feed it needs, we work out how to fix it. So yes, there is a lot of IT, but it is mainly understanding numerous scientific systems which are central in supporting oceanographic research.

I will end this post here by placing it in the public drive for the blog master to pick up over the network, and then upload via the satellite internet (yes, another system we look after!). If you want to know more about the RRS James Cook, read on here: http://noc.ac.uk/facilities/ships/rrs-james-cook

Date: 31/05/18 J151 20:48:42 << From a precision network clock

Position: 48° 58.94′ N 016° 33.03′ W << From one of scientific GPS’s. Copy into google to see in a map for yourself.

 

Written by Eleanor Darlington

2018 Cruise - JC165

Sediment Trap Recovery

27 May, 2018.

Today we recovered the Sediment Trap Mooring that we deployed on our cruise last year on the RRS Discovery (DY077).

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Figure 1. Recovery of a sediment trap on board JC165.

Sediment traps collect particles that sink through the water column from the surface to the seabed – which at the PAP-SO is 4850 metres down, just over three miles deep. The particles, sometimes referred to as marine snow, fall inside the yellow funnel into the bottle underneath. The trap is programmed to rotate the bottles so collects a sequence of bottle samples over the years’ deployment. We deploy traps at different depths from 100 metres above the bottom to 2000 metres above the bottom. This means that the top of the mooring is still 3000 metres deep so completely invisible from the surface. When we come back to collect the mooring, we send an acoustic signal, which then brings the whole mooring to the surface. It is so deep that it takes almost an hour for the top floats to reach the surface where we can see them. The bottom of the mooring takes even longer.

 

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Figure 2. Control box sending the acoustic signal to the sediment traps.

We use four different traps so that we can measure the marine snow at different depths in the water column. When we bring the samples back to the National Oceanography Centre (NOC), we measure the collected material in many different ways (such as Volume, Dry weight and Organic Carbon) so we can understand what the marine snow is made up of and how it changes as it sinks through the open ocean waters.

 

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Figure 3. Tubes collect the falling particles over the whole year.

The phytoplankton (microscopic plants) in the surface waters draw down carbon dioxide from the atmosphere so that they can grow. Zooplankton (microscopic animals) feed on the phytoplankton and in turn are fed upon by nekton (bigger animals such as fish). Together the phytoplankton, zooplankton and nekton create marine snow from their cells, moults, feeding and faeces, forming what scientist call the Biological Carbon Pump. It is called a pump because it moves the carbon from the atmosphere down into the deep ocean. If the oceans didn’t have a Biological Pump there would be much more carbon dioxide in the atmosphere.

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Shown above is the Estimated Volume Flux (EVF) over the most recent deployment. In the coming weeks we will analyse the samples in more detail to include estimates of the amount of carbon being transferred down to the oceans depths.

When we measure marine snow each month and each year, we build up a picture of how much carbon the North East Atlantic is removing. This is important because although we want to measure climate change, the oceans have their own natural variation and we must understand this and be able to separate it from any human induced change.

Written by Corinne Pebody.