Blog weeks 17, 18 & 19: The Season is coming to an End

The ice patrol ship HMS Protector came to visit the Station and we were all invited on board for a curry lunch! It was great to go out for lunch after several months sitting at the same dining tables. The inside of the ship is cosy and the social rooms are quite spacious. The Navy crew was very welcoming and gave us a tour around the ship. It is an ocean survey vessel which looks at the topography of the seabed along parts of the Southern Ocean. Unfortunately due to poor weather conditions (a snow storm with 30+ knot winds) the Rothera Olympics did not take place and the HMS Protector left a day earlier than planned.

Luckily the weather got better over time and allowed us to keep on with our sampling routine of water collection and net deployments in Ryder Bay.

Us doing a net profile at RaTS station on board of Sea Rover.

One of the experiments we perform is called Mesozooplankton grazing. Meso-zooplankton consist of all planktonic grazers bigger than 200 µm which feed on phytoplankton or smaller zooplankton. As soon as we have taken our last net haul we rush back to the lab, split this last haul into 5 portions and incubate in filtered seawater taking samples over an hour. The idea is that the gut throughput rate is a measure of feeding rate. 

As soon as you place the zooplankton population into filtered seawater they no longer have any food and so a decrease in chlorophyll is observed as feeding stops, but they continue to evacuate their guts. After a short period of time (less than an hour) the zooplankton realise that there is no food in the water and gut evacuation stops. The aim is to measure the decrease in chlorophyll content of these grazers over the time period with the initial rate of decrease being the feeding rate. This not only gives us a total gut chlorophyll content (an estimate for how much phytoplankton has been eaten) but also a gut throughput rate which gives us a grazing rate.

One of the biggest planktonic grazers to be collected, Krill

Whilst we were out boating we spotted one of the most veracious predators in the Antarctic waters, the leopard seal. Every time the divers go for a dive there is a designated person on seal watch. This person is on the lookout for leopard seals in the area. If a leopard seal is spotted, the dive is aborted and postponed for at least four hours after the sighting. Experience showed this is necessary.

Leopard seal, a 3 metre long voracious predator!

For the sake of adventure and being outdoors we had the opportunity to explore a new crevasse that has opened up on the flag line that connects the base to the recreational area. The crevasse is very narrow and is about ten to fifteen meters deep. After abseiling down into the crevasse we spent some time admiring the interior covered with ice stalactites, absolutely astonishing. To get out, we climbed up the steep ice wall using a pair of ice axes always connected to a rope, wearing a helmet and crampons. It was challenging getting out of the tight ice hole but extremely rewarding.

Exploring the recently formed crevasse near the base

Packing up all of the samples from this busy season into boxes and filling in all the Bols (Bill of Lading) made us somehow melancholic by realising that we just have one week left until the RRS Ernest Shackleton berths on the wharf, ready to take us on a five day journey North to the Falkland Islands where our flight home begins.
Rothera base has been our home for the past five months. We have had such a great time thanks to everyone being so friendly and helpful. It all contributes to make us feel just like being at home.

Home sweet home. Overview of Rothera research station, less than a kilometre in length and not more than a dozen buildings.

View from Stork Bowl (skiing hill) over Ryder Bay and the sampling station RaTS.

Before snowboarding back down the glacier I had a really enjoyable moment looking over Ryder Bay where we have been sampling almost daily over the Summer season. What a spectacular view across the bay with sea ice drifting through, islands in the background populated by seals, and distant snowy mountains.