Douglas Hamilton, University of East Anglia

Water chemistry is employed during cruises to look for various things of interest to Oceanographers like temperature, salinity, dissolved oxygen and chlorophyll.

Temperature and salinity can be used to tell us something about where the water comes from, for example warmer water originates from the hotter equator and colder water from the poles. Salinity is a measure of how “salty” the water is; new fresh water from ice melting for example lowers this, whereas evaporating water at the tropics raises this value. Salty water is of particular interest in understanding global ocean movements as it is heavier than fresh water and sinks, helping to create an ocean transport system around the world.

Dissolved oxygen and chlorophyll can be used as a measure of how biologically productive an area is. Levels of chlorophyll are related to microscopic phytoplankton (tiny plants) that live near the surface of the ocean.

Phytoplankton create their own food much the same as their larger relatives on the land, using photosynthesis to harvest the power of the sun to create sugars. Chlorophyll levels are of interest to researchers in many fields, both biological and chemical. In areas of upwelling, where water is brought up from the depths of the ocean, it carries with it essential nutrients for the phytoplankton to grow. A high chlorophyll count can help show where these nutrient upwelling regions are, or alternatively where nutrients from the atmosphere are entering through the surface of the ocean. As photosynthesis uses up carbon dioxide, the phytoplankton could help in a small way to lowering global warming if there is enough of them in the right area. Polar regions have some the highest chlorophyll levels in the world, helping to provide a strong start to the food chain and feed the large range of life living below the surface. Oxygen in the oceans is an essential part of animal life in the seas as much as on land, low levels can be potentially dangerous to many species. It is important for the safe future of all Oceans that we keep recording all these things and further develop our understanding of how these great blue oceans work.

The water to be analysed is collected using a piece of apparatus called a “CTD” which is lowered on a steel wire to the ocean depths. This consists of thick grey plastic tubes called Niskins that are mounted on a steel frame called a Rosette. A maximum of 24 Niskins can be “fired” at any given depth from a chosen location. Each Niskin collects the sample of the water traversing through it by snapping shut two water tight bungs at either end.  It is common practice to collect the water as the Rosette is ascending to the surface, this is because areas of interest spotted on the descent can be the ones captured. This water is then analysed onboard the ship using different techniques. Oxygen is measured by titration using the Winkler method which traps all the oxygen in the water. Chlorophyll is measured by filtering the water through filter paper and measuring the green bits in leftover cells with a fluorometer. Salinity is tested with a clever instrument that measures all the various salts within the water.

Sending the Conductivity-Temperature-Depth (CTD) recorder into the Weddell Sea to collect oceanography data. Photo: Melanie Mackenzie, Museum Victoria

Douglas Hamilton (University of East Anglia) doing some water chemistry. Photo: Jim Rudd.

Position Report for Entry

Melanie Mackenzie – Museum Victoria

Now that we’ve finished collecting specimens, the EVOLHIST biology team on board the James Clark Ross is busily working away in the ship’s labs. Dr Jen Jackson has been working with the British Antarctic Survey (BAS) for the past two years, using her skills in molecular science to help build a ‘big picture’ of animal evolution in Antarctica. For this cruise Jen has been focussing mainly on jellyfish and sea cucumbers and is hoping that the DNA sequences she gains from these will eventually will help to give us a better idea of how species from the Weddell Sea relate to those from other parts of Antarctica.

Dr Jen Jackson extracting jellyfish DNA on board the James Clark Ross. Photo: Melanie Mackenzie - Museum Victoria.

Dr Jen Jackson explaining DNA extraction techniques to Stuart McMillan of BAS. Photo: Melanie Mackenzie - Museum Victoria.

Stu McMillan of BAS is helping Jen out with her DNA extractions today.  Together they are placing tiny pieces of animal tissue in small plastic vials, then pipetting, lysing (using enzymes to break the material down) and spinning these samples until their DNA is in an appropriate form for testing back in the BAS lab in Cambridge.  While Stu has a background in zoology this is the first time he’s been ‘back in the lab’ for quite a while – kept busy as the cook/dustman from UK’s Antarctic Halley Base where we recently picked up a very happy (and mostly bearded) group of 21.

The crew hard at work at Halley creek 3. Photo: Melanie Mackenzie - Museum Victoria

Waving off the Halley 6 winterers. Photo: Melanie Mackenzie - Museum Victoria

The summer crew have been busy readying the new Halley 6 for its first winter. While we were not able to visit the ‘big blue caterpillar’ ourselves, we had the amazing experience of being allowed off the ship for a couple of hours on the ice-shelf as the crew busily loaded gear onto the James Clark Ross.

After the requisite safety-briefings from 2^nd Mate Tim, Captain Jerry happily waved us off from the Bridge and we were free to run around like school-kids on a snow day – extremely happy to ‘stretch our legs’ after a month and a half on board.  Marine geologist Alex Tate took this to another level, running a lazy 10 kms as the rest of us wrote messages home in the snow.

Team photo at Halley creek 3. Photo: Richard Turner - British Antarctic Survey

Rachel Downey (British Antarctic Survey)

We have been working in some amazingly calm waters for the last two weeks, and are now breaking through the sea ice again as we leave this part of the eastern Weddell sea for a rendezvous with our Halley base colleagues. We have been sailing close to the Antarctic ice shelf, and have been able to see not only how impressive they look close up but also how colossal they are too! We have been getting this close to the ice shelf in order to map the shelf break, as Antarctica has some of the steepest shelves in the world, which can plunge from 400 m to 2000 m in just 2 kms. We have also found some really interesting gully features too, which will help our colleagues back at BAS to understand underwater sediment processes in this area.

Swath Bathymetry images of the shelf break in the Weddell Sea. Image by Alex Tate

Our journey through the sea ice towards the ice shelf has also given us dozens of wildlife spotting opportunities. Groups of Emperor penguins and Crabeater seals can be seen resting on many of the icebergs we pass. Large groups of Minke whales are also fond of feeding in this area, so there are plenty of opportunities during our working day to snap a couple of photos for the folks at home. Birds are surprisingly common round here as well, with petrels and terns often seen flying with the ship or resting on sea ice around us.

Two Crabeater seals on the ice

Snow Petrel. Photo by Huw Griffiths (BAS)

Emperor Penguin. Photo by Huw Griffiths (BAS)

In just over 2 weeks we have nearly completed our biology sampling of a wide selection of sea floor environments. Our trawls and underwater camera footage have shown us just how incredibly diverse and colourful Antarctic sea floor life really is. We have come across muddy sea cucumber ‘cities’, bryozoa (moss animals) reefs that are as impressive as any tropical coral reef, and rocky sponge gardens jam-packed full of animals.

Different habitats from the Weddell Sea captured on underwater video. Photo by Huw Grifiths (BAS)

Excitingly brittle stars of all different shapes, sizes, and colours were found in great numbers this week. We all took turns to climb into the nets to get them out carefully with tweezers! BAS are currently heading the largest brittle star DNA bar-coding project of the Southern Ocean, using this abundant group to help us understand the evolution of Antarctic sea floor life. The southern Weddell Sea is a completely new sampling area for this project, and me and my colleagues, Chester Sands and Huw Griffiths, hope to learn lots of new facts about this charismatic group.

Antarctic Brittlestars. Photo: Camille Moreau (BAS)

Working and living on a ship has been an incredible experience for all of us scientists on this cruise. All the crew have been superb in helping us complete our scientific work. Even though we are on a moving ship in one of the remotest areas you can find on the globe, we still enjoy some of the everyday touches of normal life, such as regular circuit training in the bowels of the ship to keep us in shape, and even a pub quiz after a hard day’s work. During this cruise, we have successfully gained our sea legs in some of the roughest oceans in the world, become expert whale and penguin spotters, and have got firsthand experience of just how amazing and unique Antarctic marine life really is.

JR275 Biology team