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

Gaining experience on the high seas!

If someone had told me in May of 2016 that in two years time I’d be on a research cruise to the PAP-SO, I would not have had a clue what they were talking about. At that time I’d been working for 4 years on commercial fishing boats as a fisheries biologist in Alaska and only just starting to look for other opportunities, particularly in higher education.

I hadn’t even heard of NOC, the James Cook, or the University of Southampton. Yet here I stand, an inexperienced masters student with the deep seas benthic group taking full advantage of every opportunity; slicing megacore samples, cutting through fish for amphipods, putting together traps, sieving zooplankton, labeling everything, asking questions, and peering over other people’s shoulders.

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Blessed with inexperience, every moment is a learning opportunity. Even at the birthday celebration onboard I had a discussion that pertained to my masters thesis and European conservation efforts. The easiest way to start a conversation is asking someone about their day, and in doing so learn the many aspects of studies being conducted onboard. Lunch topics have included individual projects (who knew there was deep sea fungus?), HyBIS, how courses work in different countries, funding, the CTD sensors, amphipods, holothurians, tardigrades, abyssal fishes, writing proposals, the prospective trawls, and how everyone has gotten to being a part of the cruise. Just walking down the hall yesterday I peered into a bucket containing a portion of a deep zooplankton tow and saw a chaetognath and a very active amphipod. I helped with a zooplankton night tow and saw a couple hundred active amphipods, copepods, glowing blue flashes, and even a few pteropods!

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Going through the cores every night could become monotonous, but the benthic gang turns up some tunes and most nights there is something to investigate at the top of a core. The excitement of seeing something, really anything from those depths, instantly has all of us crowd a core. Is it a foram? A polychaete? More green fluff? In the past day we’ve added pteropod test, large xenophyophore, and unknown ascidean to the list! Just this morning the group collected two unknown items from the top of the sediment, including the unknown ascidean, which looks like a beautiful, nearly blooming flower under the microscope.JC165

Surrounded by interesting equipment, samples, and people aboard the RRS James Cook, I’m soaking it all in and enjoying.

 

Written by Virginia Biede.

 

 

2018 Cruise - JC165

Baited beasties, or the scavengers of the deep.

Our first amphipod trap was deployed on Sunday morning and left to ‘soak’ on the PAP seafloor for about 40 hours before recovery. Amphipods are small crustaceans, shrimp-like in form but without a carapace, bearing different kinds of appendages on their thorax and abdomen, with impressive claw-like structures that can grip almost anything. The amphipods we collect at PAP are bentho-pelagic; they live on or close to the seabed and they are particularly ferocious! In fact, like piranha in the Amazon River, they can devour any ‘attractive’ prey, whether alive or dead. To attract these little deep-sea beasts, we use four dead mackerel as bait placed in funnels inside large cylindrical tubes mounted on a sampler that we simply call the “Amphipod Trap”. Deep seas are usually food-limited environments; benthic fauna relies mostly on the particulate organic matter that originates in surface waters and degrades through the water column before reaching the seafloor. We use the mackerel to simulate a natural food-fall that will appeal to scavengers.

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Figure 1. Scientists waiting for the Amphipod Trap to come up to surface (left), and crew members trying to catch the trap with a hooked rope (right).

The trap is deployed from the afterdeck and sinks down to the Porcupine Abyssal Plain. A pair of bottom tubes containing the mackerel sits about 50 cm above the seafloor, and a top pair sits about 1 m above. When they smell the dead fish, the amphipods, many of the genus Eurythenes, swim into the funnels where they end up sampled. Depending on how many amphipods are trapped in the funnels and how long we leave the trap in the water, we sometimes only recover the bones of the fish (see DY077 Discovery 2017-cruise), and observe the largest specimens already eating the smallest ones. As if a whole mackerel was not enough!

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Figure 2. Amphipod trap recovery on the after deck. A mackerel was placed as bait inside each of the four funnels to attract the deep-sea amphipods.

To recover the trap scientists release a trigger that ‘calls’ the sampler to come up to the surface. Crew members then catch the trap using a hooked rope before it can be brought back on the afterdeck. It is then our turn, were we process the samples; we collect all individuals caught in the trap and preserve them in ethanol. This will allow morphological and genetic analysis once back at NOC in Southampton.

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Figure 3. Scientists part of the ‘Benthic Team’ picking out all amphipods trapped in the funnels before preservation with ethanol (top).
Example of deep-sea amphipods (bottom), many of the genus Eurythenes, collected on the PAP seafloor. Note the broad body-size range and morphologies of these little, necrophagous, creatures.

During this first deployment, the fish were not completely eaten, yet we collected a few hundreds of individuals. We aim at deploying at least two sets of samples during the cruise. NOC scientists have been collecting these deep-sea amphipods at PAP for over 30 years in order to assess any change in species abundance, diversity, and composition over time. These biological data are then related to local environmental factors such as food supply to the seabed and temperature that may explain the observed patterns of the baited beasties.

 

Written by Noëlie Benoist.