PICCOLO
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Gareth, Gethyn and Kate alongside the recovered scientific samples. Image: Sophie Fielding (British Antarctic Survey)27–28 January 2024
On 28 January 2024, the PICCOLO expedition dramatically recovered a mooring they deployed on the Antarctic seabed in March 2023.
Professor Tom Bell from the Plymouth Marine Laboratory explains:
The PICCOLO mooring is a set of equipment on a wire attached to the seabed. It is designed to periodically make measurements and collect samples from the surrounding seawater. It is about 80m long and was deployed on the seabed in 400m deep water in March 2023. The mooring has sat on the seabed throughout the Antarctic winter, narrowly avoiding getting smashed to pieces by various icebergs, including A23 (which is twice the size of London!).
The data that has been collected is invaluable as it gives information about the processes that take place during winter, when this area is completely covered with ice. These processes affect the flow of water into the deep ocean and the amount of carbon that the water contains. This is a crucial element of the PICCOLO project, and a major scientific win.
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UEA's Karen Heywood recounts this dramatic recovery:
So, early on Saturday (27 Jan) we set off in trepidation from the Seymour islands, and we were pleased to find that the sea ice wasn’t too thick for the ship to reach the site where we had left our PICCOLO mooring. The first thing is to send a “ping” – a short pulse of sound to see whether the gadget that releases the mooring is there. It’s called an acoustic release. Here are British Antarctic Survey’s (BAS) Sophie Fielding and Gareth Flint (UEA) listening carefully to see if the acoustic release answers.
And yes! The mooring replies! It’s there! Everyone celebrates! But Sophie says we shouldn’t celebrate until the mooring is safely onboard the ship. She’s right of course.
We get ready to recover the mooring and its precious year of data. But bad news. We discuss with the captain and the crew and it’s agreed that it’s too risky to send the mooring up to the surface – the sea ice is closing in and drifting quite fast with the currents, so we are afraid the mooring might come up under the sea ice. Visibility is poor as well, so we might not spot it. No point taking a risk at this stage. We decide to wait until the next day.
On Sunday morning the conditions are better – it’s not as foggy, and there is a suitable gap in the sea ice for releasing the mooring into. We agree to release the mooring, and send the acoustic signal. It should be on its way to the surface. Then we wait, for what seems like ages. Everyone is up on the ship’s bridge looking out, waiting to see a small orange blob in a large expanse of blue and white. After about 5 minutes there’s a shout of “there it is!” and everyone shouts and cheers.
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Now the ship’s crew get into action like a well-oiled machine, carefully grappling for the buoy floating at the surface, and then moving it painstakingly to the back of the ship. It wouldn’t do for the ship to run it over now and lose it. Then they start to winch in the instruments one by one. As each one comes onboard we breathe another sigh of relief. The big orange buoy has instruments on it to measure the ocean currents.
We’re particularly excited about this instrument – it captured a bagful of seawater near the seabed every few weeks, and we’re going to analyse this to see how much carbon is in the water.
Once everything was safely onboard, we celebrate! But Sophie says, don’t celebrate yet until we see whether all the instruments actually measured anything during the year. Maybe they stopped working on the first day. She’s right, of course.
The next few hours are spent checking the instruments, and it’s good news! We managed to collect some water in the bags. We don’t think anyone has ever done this before in the Antarctic. And there are some exciting data sets that we’re now itching to get analysing.
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We learn that our mooring did indeed have an eventful year – one of the sensors is full of mud! We’ll have to see how close the mooring came to that pesky iceberg. But luckily the mooring survived. What a day! Everyone is elated, but no time to rest – the mooring team get busy preparing all the instruments to put the mooring back in the water the next day. We want to get another few weeks of science data, this time more frequently. But maybe time for a celebratory iced doughnut?