New article in the SANCOOP newsletter, December 2016:
Read the full story by Wiida Fourie-Basson in Stellenbosch University News: http://www.sun.ac.za/english/Lists/news/DispForm.aspx?ID=2071
Stellenbosch University will have a large contingent of young researchers from earth sciences and engineering on board the SA Agulhas II’s roundtrip to Antarctica this year.
Eight postgraduate students from the Department of Earth Sciences, and three postgraduates from the Department of Mechanical and Mechatronic Engineering, will investigate a range of topics. This includes motion sickness and the impact of wave slamming on the ship’s hull, as well as the genetics of algae and mapping bacterial communities in the Southern Ocean.
While the students are obviously very excited about this once-in-a-lifetime opportunity to travel to the South Pole, Prof Roy Roychoudhury warns that there will be very little time to gaze at the ice bergs on this cruise: “We get this chance only once a year. These students are often going to have to work 14 to 16 hour days.”
The team from the Department of Earth Sciences (five honours, one MSc student and a postdoc) will be tackling aspects of the same problem, and that is to understand the link between the growth of algae in the Southern Ocean, the cycling of essential chemical elements and how that impacts on the levels of CO2 in the ocean and the atmosphere. The students are Ms Natasha van Horsten (30), Ms Leigh-Anne Palmer (21), Ms Gillian Trollope (22), Mr Ryan Cloete (23), Mr Jean Loock (23), Ms Mari Scott (22) and Dr Raissa Philibert (27).
The link between iron, algae and CO2
This will be the third year in a row that MSc-student Natasha van Horsten (30), currently an intern at the CSIR in Stellenbosch, will be on board to collect samples. She has already established that algae grows faster when there is more light and more iron available, but it seems as if some algae communities are able to utilise iron much more effectively, despite low light and low iron conditions. Natasha is now collecting data for her PhD, where she will be looking at how much light the different algae need to effectively use iron. A postdoc from the University of Cape Town, Dr Raissa Philibert (27), will take samples to investigate the genetics of the different algae communities in order to help finding the gene responsible for the difference that Natasha finds in how they use iron.
But iron may not be the only factor influencing the growth of algae and photosynthesis, explains Prof. Roychoudhoury. “We are trying to simulate real life conditions. It is one thing to study algae growth under controlled conditions in a lab. It is much more difficult to understand what is happening out there in the real ocean. That is why we are following an integrated approach”.
Honours student Leigh-Anne Palmer (21) will therefore be sampling for macro nutrients like nitrogen, phosphate and silicate, while Ryan Cloete (23) will sample for micronutrients like iron and other trace metals (such as zinc, cadmium, copper and manganese). All of these nutrients are important, in varying amounts, for the growth of plankton.
So far it has been assumed that iron is the main limiting factor for plankton growth in the Southern Ocean. But depending on the site and algal and microbial communities, other macro- and micronutrients may be equally or even more important limiting factors.
Another honours student, Jean Loock (23), will be hunting for nano-sized iron particles at the different sampling sites en route. A previous study showed that there are different kinds of iron in the ocean, and that plankton grows best when the more easy-to-use iron, called Fe(II), are available. But Fe(II) seems to be in short supply, while the not-so-easy-to use iron, Fe(III), are much more abundant. Jean’s research will look at the molecular structure and character of these different types of iron.
Prof Roychoudhury says that iron (after zinc) is probably one of the most difficult metals to sample due to its low concentrations in the ocean, but also because of its ubiquitousness as a contaminant: “Iron is literally everywhere on the ship itself and on the instruments or containers we use to sample. A few decades ago scientists believed there was loads of iron in the oceans, because they did not realise that their samples were contaminated by outside factors. Today we use extremely sensitive analytical methods to sample, filtrate and store the samples.”
An important aspect of Ryan and Jean’s job will be to demonstrate that their method for collecting, filtering, storing and analysing the samples are on par with the rest of the world’s clean labs.
“Our samples will also be sent to labs in the US and the UK for calibration to ensure that no contamination occurred either during sampling or at the lab. Only when we can show that all protocols were adhered to, can we share our results with the rest of the world,” says Prof Roychoudhury.
Another major research question is to understand where the iron originates from in an ocean as vast and far away from land masses as the Southern Ocean. For this reason Ms Mari Scott (22) will study whether the dust deposited in the Southern Ocean leads directly to stimulated algal growth or more efficient photosynthesis. Most of the dust in the middle region of the Southern Ocean is blown there from Patagonia by the notorious Westerlies.
The students and junior researchers will also be sampling for bacteria in order to figure out which species, and how many different species, there are. It seems that some phytoplankton and bacteria species are able to excrete substances that convert unsuitable iron into iron ready for uptake. Knowing who lives where and who’s doing what with iron, may change current perceptions about the availability of iron in the SO. Back on land next year, the microbiologists will be called in to investigate whether some of the species sampled have special genes designed to convert iron into a form more suitable for algae growth.
Ms Gillian Trollope (22) has the task of collecting ocean water samples from different depths as part of another South African National Antarctic Programme project which will run from 2015 to 2017. Dr Susanne Fietz, an environmental biogeochemist at SU and project leader, says they want to find out if modern molecules, which will become geochemical fossils once they settle down onto the seafloor in a few thousand years, reflect current sea water temperature changes in the Southern and Antarctic Ocean. In a recent study, researchers found that geochemical fossils have preserved the chemical signal of specific environmental conditions in the Arctic as far back as 2.6 million years. They are now using that information to reconstruct past climates. Dr Fietz wants to investigate whether the same method can be applied to modern sea water in the Southern Ocean.
The last student from the Department of Earth Sciences to get on board is MSc student and geologist Hendrik Smith. He will be going down as part of a Council for Geosciences team run by Dr Geoff Grantham. Based on his experience in geological mapping and his expertise as an avid rock climber, Hendrik will provide training in ropework, self rescue techniques and assist with geological mapping and sampling.
We thank Wiida Fourie-Basson for the interviews!!
Find out more about wave slamming, motion thickness and ice crushing at http://www.sun.ac.za/english/Lists/news/DispForm.aspx?ID=2071