Research Cruise to the Porcupine Abyssal Plain – Sustained Observatory: why we do it and love it and why we keep doing it and keep loving it. Corinne Pebody

I have just returned from our annual pilgrimage to the PAP-SO in the Northeast Atlantic, where we have somehow managed to cram 108 stations into 13 days!

The PAP-SO or Porcupine Abyssal Pain – Sustained Observatory, at 49⁰ North and 16⁰ West, is two days sailing west and a little south from the UK. Beloved and sampled for over 20 years, we have an amazing mix of year round moorings, short term deployments and sharp snapshots of processes and parameters. An April cruise can be at risk from bad weather, but the benefits of observing the start of the spring bloom are huge. This year we lucked out again and the weather didn’t blow up until our very last day. All credit to Captain Jo Cox’s incredible weather prediction, getting us off site within an hour of the blow, optimising our sampling effort without risking kit or limb.

corinne1PAP-SO image from Google Earth.

Swell aside, there are always ups and down on cruise, steel hearted scientist – we aint, knowing that these two weeks on site are the only chance for a whole year, adds pressure to the knowledge we either get it right or wrong, no in between and no second chance, just another year’s data lost. It makes us care and careful, applying our left brain to all the fine details and simultaneously, our right brain to put our big pictures together. Cruises are amazing adventures, motivating; totally immersive and both invigorating and exhausting.

corinne2PAP1 mooring being deployed.

The big buoy is PAP1, our surface to seabed mooring spans 4900 metres of water. Each year we change over instruments and calibrate both those incoming and outgoing, to get the best possible data sets; more and more of which are becoming available in real time. (http://projects.noc.ac.uk/pap/). In our pelagic team, we each take responsibility for two or three instruments and setting aside our logical brain, it’s always an emotional high to get our instruments back and take the data off, calibrate it and then make the most beautiful plots of seasonality. Now we’re able to synthesise more parameters together the picture becomes both more interesting and more complex, like each character telling their narrative in an unfolding story, some shout and some need encouraging to get their truth out. By putting them together we get the bigger tale, though tantalisingly never the full story, there is always an echo of another voice, another parameter to be included that would inform and explain more and better.

corinne3PAP1 frame being craned over the back of Discovery.

We know that we are truly challenging the instruments by deploying them for twelve months in a physically challenging, not to mention wet environment; but the results we do get just make us drive them harder for better resolution, better longevity, and better accuracy. Our data addiction makes us hard task masters but open oceans are complex systems and sometimes we have to throw the ‘assuming a steady state’ baseline right out of the window. This is where the PAP-SO really comes into its own, we keep adding new instruments (just ask the long suffering mooring technicians) as they become tough enough for us to use. Sometimes they fail, sometimes we have gaps, and the crushing sight of a fizzing end cap, or the total utter silence on application of power and coms, is a sight we have yet to get hardened to.

My personal highlights (other than the 5 birthday cakes that were provided by the fabulous Amy) are the particle flux and the zooplankton that are such major players in its production. ‘Green gold’ in the bottles from last year, occurred in incredibly high volumes in the spring and summer. Our quick ‘n’ dirty measurements and photos revealed a fantastic year and I’m looking forward to more focused analysis to tease apart what’s happening, when and who’s making/eating it?

corinne4

Bottles containing particle flux over the year. The full bottles of brown ‘stuff’ are from spring and summer months.

I’m more and more convinced that pteropods (large shelled zooplankton) are key players in downward particle flux and these large zooplankton have a complex tale that is still be told. However, their aragonite shells are potentially vulnerable to ocean acidification adding time pressures to getting their life story told. I just need to ask the right questions, not easy when the usual method of collecting them at the PAP-SO is by net and that brings up a stressed, half dead animal. Last year we were lucky enough to accidently collect a live animal. I managed to record rare swimming action of this beautiful animal, but it didn’t extrude a mucus web, which I want to collect, analyse and measure it’s contribution to downward particle flux.

Corinne taking photos (left) of the beautiful pteropods (right). This pteropod is called Clio pyramidata, showing the soft tissues retracting back inside the shell.

Luckily we have another collection method. The sediment traps that we use to collect the particle flux also captures occasional unfortunate zooplankton including pteropods. I can observe seasonal and inter annul distribution of pteropods in relation to flux material and this I think is my key – if I can only unlock the code. Again I need to ask the right questions to get the right answers and I am looking forward to a year that may be unravelled enough to reveal just a bit little more of the pteropod mystery.

Corinne Pebody is a particle flux technician at the National Oceanography Centre, Southampton.

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