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  • Writer's pictureAlexis bahl

Steaming to the Southern Ocean: Part 3

This blog is intended to capture the experience of the Macrozooplankton and Micronekton team led by Evgeny Pakhomov, comprising Lora Pakhomov, Florian Lüskow, and myself on board the Alfred Wegener Institute’s Polarstern research vessel. From October 1st – November 17th for the PS 133-1 Island Impact cruise to the South Atlantic sector of the Southern Ocean, we will record daily insights of the activities on board, with a personal perspective of what it’s like conducting science at sea. All thoughts are ours and are not to be taken for media use. This work is funded by Alexis Bahl's 2022 Explorer Grant with the National Geographic Society.

 

Day 21: Midnight krill

October 21, 2022


The last days have been busy with data processing and station planning. Last night, both CTDs were deployed, as well as the mesozooplankton’s two MultiNets, and finally our IKMT. At 12:03 am, I watched from the warm control room as Florian and Evgeny worked with the crew to deploy the IKMT off the back of the ship. Planned for a max. depth of 200 m, it did not take long for our net to reach its end point and exit the water. The net was pulled onto the deck and Lora rushed out with a bucket to retrieve the sample. As soon as the bucket was set onto the floor of the wet lab, people came in amazement to watch the jellies, krill, and polychaetes swim around before we began processing.


Surprisingly, this sample contained a few larvae forms of Euphausia superba, commonly known as Antarctic krill – a hot commodity for fishery harvesting – which must have drifted from the continent after a long winter of feeding on the ice algae. Despite working closely with my global colleagues on some Antarctic krill projects, I had yet to see it in person, so I was rather excited to get a close look. Pictured below are different species of Euphausiids, Pteropods, and Amphipods.

At 200 m in the peak of the night, we expected many zooplankton to be present in the surface layers due to their daily migratory behaviour. During the day, they seek refuge from visual predators in the deep, dark layers of the ocean, but at night, when the sun has set, they migrate in masses to the surface to feed.


As I sit in the wet lab writing this post, after having entered all the species we counted last night into our excel sheet, I look forward to our next process station which will occur in less than 24 hours. So much more to see!

 

Day 22: Long nights making new friends from the sea

October 22, 2022


Two days in a row the weather has allowed us the opportunity to sample the macrozooplankton and micronekton community of the South Atlantic sector. Similar to yesterday (Day 21), the IKMT was deployed, but before deploying the IKMT to ~200 m, Florian and Evgeny prepared the monster net (aka, RMT-8) to begin our midnight sampling efforts. As usual, I sat in the control room where I had a clear view of the net entering and exiting the water so I could write down details such as latitude, longitude, time, water temperature, salinity, and more. Our team, as well as the crew, has increased in efficiency to the point that the RMT-8 takes less than 50 minutes to sample an integrated tow to 600 m, and the IKMT only takes about 25 minutes to do an integrated tow to 200 m.


After pulling the RMT-8 net up from the water, Lora went out to the deck with a bucket to retrieve the sample found in the cod-end of the net where all the organisms filter to. Retrieving organisms from the deep is an interest to more than just our team! Pictured below are scientists from other teams that have come to see what peculiar-looking individuals we’ve managed to catch. Florian and Evgeny, all included in the photo, continue pulling out similar species from the catch to begin separating, which eventually required identifying, counting, and measuring.

 

Day 26: Zoop updates

October 26, 2022

On the 26th day of the cruise, our team leader, Evgeny Pakhomov, gave a wonderful presentation to all the scientists on the status of our work thus far, pictured here. Every night, all of the scientists group together in the Kino (cinema room) to hear about the weather forecast, station plans/changes, and most often, a presentation showing recently collected data, or simply a short overview of how this cruise is related to outside work. Today I sat eagerly in my go-to spot as I listened to Evgeny brief everyone on the types of macrozooplankton and micronekton groups we were coming across, as well as our initial findings on the salp community throughout the region. Any further details can be found in the manuscript that will come out of this cruise so keep your eyes open.


Photo credit: Florian Lüskow

 

Day 28: Mid-way celebration

October 28, 2022


Celebrating the mid-point of a cruise is important on every expedition. In Polarstern’s Germanic way, this celebration is referred to as the Bergfest, translating to the hard way up the hill has been managed and from now on the days will fly by as it goes downhill. However, it so happened that the Bergfest fell exactly at the time of an oncoming hurricane with a Beaufort scale of 12 (a wind strength scale – more information here). Before any celebration began, we, therefore, had to seek shelter from the massive storm that was affecting the entire Southwest Atlantic. When on a ship, this means hiding behind any close-by landmasses. Luckily, we found a protected bay in the Falkland Islands where we “weathered the storm” for about two days. In Port Stanley, close by we cannot dock due to Polarstern's deep draft, but the Falkland Islands provided a barrier from the wind, and therefore wave height was reduced compared to being out in the open ocean. Regardless, seeing and smelling land after four weeks at sea was a welcomed change. Protected by the desolate green island hills, the chef and crew prepared a magnificent BBQ to be served partly on the open deck. Treated with sunshine while grilling various meat sorts, including ostrich and kudu from South Africa, the Bergfest was a true celebration that everyone enjoyed. Long after nightfall when the crew and scientists had finished mingling outside, everyone grouped inside where the scientists manned the bar and the music. The dance floor came alive - during these hours, the ship’s belly made it possible to forget about the demanding work and the storm we had just braced. On the next morning, we left the Falkland Islands and returned to our sampling programme.

Weathering a hurricane in a sheltered bay at the Falklands Islands (left picture) and disappearing archipelago on the morning of 29 October (right picture). Photo credit: Florian Lüskow.


To be continued...

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