University of Tasmania, Australia

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Interview with Cathryn Wynn–Edwards

Cathryn Wynn–Edwards: Ocean acidification and its effect on Krill diet.

Despite the Tasmanian summer, Cathryn is bundled up in thick clothes and overalls. Well into the second year of a PhD, her experiments are in full swing and Cathryn spends most of her time bathed in the coloured light of the phytoplankton tanks. Cathryn's project brings together expertise from UTAS, CSIRO, and also the Australian Antarctic Division - where she works in the Krill Aquarium. - Keeping Antarctic species alive, and the krill in breeding condition, requires refrigeration at Antarctic temperatures – hence the padding.



 Cathryn has to monitor the carbon dioxide being pumped into the tanks, at the Krill aquarium.

The phytoplankton is being grown to feed the krill and the difference in colours – bright, almost fluorescent- green, orange and red are due in part to the different species which are being cultured in the transparent cylindrical tanks. The different shades of these colours are due to the concentrations of phytoplankton, Cathryn's phytoplankton are kept at low densities, they give the tank a faint yellow tinge. Her tasks are to monitor the dissolved carbon dioxide levels in the tanks and keep them at specific levels. This requires that she keeps the phytoplankton concentrations low too; high concentrations of phytoplankton can rapidly reduce carbon dioxide levels in the water.

The goal of your PhD is to contribute to models predicting krill biomass, why the Phytoplankton tanks?

"Everyone is concentrating on the direct effects of ocean acidification on the krill, such as potential effects of increased acidity on embryonic and larval development, but not many are thinking about the indirect effects. What is going on with their food? My project brings two things together, the phytoplankton ocean acidification side of things and krill and ocean acidification and I need to try and bring the two together."

"Increased levels of carbon dioxide, and the accompanying increased ocean acidification, have been shown to affect the composition and nutritional quality of primary producers". Growing Antarctic phytoplankton at different carbon dioxide levels will allow Cathryn to analyse the effects on larval krill which are fed the phytoplankton.

"Krill are really topical at the moment; we get heaps of 'tourists' visiting the lab and aquarium, by whom I mean important AAD guests, like Antarctic expeditioners, and even the Mayor of Hobart. I am low level for now; I am sort of quietly working, until I can go 'Ta da' with my results!" (laughs)

What got you interested in this project?

"Well to start with it was just a fictional idea. I was already studying ocean acidification, but the idea of this project came from an honours assessment to produce a fictional grant proposal. Looking at the effects of ocean acidification on a single phytoplankton species, Emiliania huxleyi, I read a lot of papers and then I thought, well, it would be tragic if one species goes extinct, but looking at an entire ecosystem it would be even more disastrous if all the phytoplankton changed somewhat in their nutritional composition. What would happen to all the animals that feed on it?"

"That was how I got the idea, and after I had written up the proposal I decided to send it to Dr So Kawaguchi: I knew he was doing this kind of work right here at the AAD. He thought it was a good idea, and it went from there."

Tasmania is a long way from Germany. How did you end up on the QMS programme?
"I was actually already in Hobart, doing an honours degree in the plant science department at UTAS. After completing a diploma in Marine Biology at the University of Bremen I wanted to travel to somewhere new."

"After I developed my project proposal the QMS programme was an obvious choice for a PhD."

What most attracted you to QMS?

"My brain is not mathematically orientated, but I really enjoy it. It is a challenge, but modelling is one of the main reasons I chose to do a PhD with QMS. It's a skill you really need these days, at every conference most of the talks have some sort of modelling aspect in the project. The QMS courses provided a useful introduction to modelling."

"Also QMS, being an inter-institution programme means I have a supervisor for every aspect of the project. I have six supervisors. Six is really a lot and I would not recommend that to everyone, but it is great to have several points of view. I have realised the more people you talk to the better off you are."

It may be early, but have you got any ideas for what happens after the PhD?
"I don't want to be too focused on one thing and get stuck with krill for the rest of my life, but I definitely want to carry on with the ocean acidification side of science. I would like to go back to Europe for a little while and work, but I would not mind coming back and working here in Hobart."

"I really like Hobart, it has all this nature that is so close by, you just jump in your car and in half an hour you are in a national Park, or on an amazing beach, listed in the top ten in the world, and there is no one else there. In Germany, you have to really travel to get to any pristine nature."

"And importantly career-wise I think Hobart is actually a good spot to be. Hobart with institutions like with IMAS, CSIRO and AAD is a hub, especially for marine science and for Antarctic studies."


Nicholas Jones