Antarctic Waters Yielding up Their Secrets
10 Jul 2006 - Interviews
Filip Volckaert - Copyright: Katholieke Universiteit Leuven
© KUL / KUL
Filip Volckaert is Associate Professor of Evolutionary Biology and Marine Biology at the Katholieke Universiteit Leuven in Belgium. He is co-coordinating an international research effort, PELAGANT, which looks to better understand the ecology and unusual biodiversity of the Antarctic marine waters. Involving participants from other Belgian universities and researchers across Europe, in Canada and Japan, PELAGANT is examining how severe climate and millions of years of isolation from other marine systems has created some intriguing eocsystems, species and populations.
Professor Volckaert presented PELAGANT's work in the March BEPOLES workshop in Brussels. SciencePoles recently interviewed him about the project.
Why is biodiversity in the Southern Ocean important?
In terms of the big picture, the Southern Ocean is a crucial part of our climate system. The micro-organisms there act as a vast biological pump, drawing carbon dioxide from the atmosphere and storing it in the ocean's ecosystems. Conversely, it's also important to know about what happens to carbon storage as it moves from lower trophic levels (the micro-organisms) up through the food chain.
The other major reason for our work is the sheer opportunity of documenting a very little known part of the globe's biodiversity. While there are fewer species in the Antarctic compared to other marine environments (only 300 fishes or so compared with 600 in the Mediterranean and around 1,000 in the North Atlantic) these are some of the most intriguing marine species on the planet. Pelagic (or sea-based) diversity in the Antarctic waters has evolved in relative isolation for the last 20 million years. We try to understand how these extraordinary fish and other marine organisms have come about.
So how unique is Antarctic marine life?
Consider for example the nothothenioids, or ice fishes. These have a very high glycol content in their blood to keep it liquid at sub-zero temperatures (as the salty ocean keeps liquid down to -1.5 degrees). The glycol has applications in freezing processes (delaying the formation of water crystals) and hence in food technology. Perhaps most curiously, they have no haemoglobin in their blood. This then requires that their hearts be twice as big as other species, in order to be able to oxygenate their body sufficiently. Looking at their huge cardio-vascular systems, we've learned more about the limits of heart performance.
What is PELAGANT's approach to analysing Antarctic marine ecosystems?
Our research is in two major areas. One group, centred in Liège, is focused on documenting and modelling the dynamics and numbers of marine organisms across time and space. This work looks to document phytoplankton productivity and nutrients as well as zooplankton diversity, particularly the smaller components. Those data are then used in models, linked to physical oceanography, that predict marine species' behaviour under varying conditions.
Here in Leuven we are focused on trying to understand and document the differences between and within Antarctic fishes (particularly in the younger stages), including looking at "barcoding" fish and improving knowledge of phylogeography and genome evolution.
What is "barcoding"?
After species have been identified with a good physical description and information about their distribution, there can still be confusion about their true identity. Some "cryptic species" look very similar but belong in fact to very different species. "Barcoding" uses the DNA code (like barcodes found on retailing goods) to pinpoint and catalogue particular species to solve cases of "mistaken identity". It is being used in other parts of the globe (as part of the FishBOL project) and is now being adopted in the Antarctic.
For each of 50 species collected so far, PELAGANT is taking a fragment of DNA and looking at its sequencing. Eventually, we'll document all 300 Antarctic species. Then we can really use the database in interesting ways. One example would be testing fish caught by commercial fishing vessels to assess whether they've been caught in approved fishing zones.
And phylogeography and genome evolution?
After completion of the human genome project, funding became available to do some very significant research into genetic information. This has enabled further insights into what has happened where (and when) to differentiate one species from another. Interestingly, there are sometimes cases of separate evolution, where the same species has developed along slightly different paths in isolation from each other. We use genome (DNA) evolution to help us map the "phylogeography" - the where and when of species evolution and differentiation.
Is it possible to see the history of a species in its DNA?
Physical environments have impacts on the reproductive output of animals, which can be traced through its genome. We can see this most clearly over the last 3 million years " in the Pleistocene and the Pliocene - enabling us to see how particular populations within a species, in differing geographic areas, have been affected over time by their circumstances.
What's fascinating is that a lot of the evidence from the genome can be correlated with what climatologists are finding out about changes in climate over this period - for example CO2 concentration fluctuations, levels of atmospheric dust or chlorophyll productivity. This work has been done fairly authoritatively for the North Atlantic and the same kind of findings are now emerging in the Antarctic.
PELAGANT is developing computer modelling to forecast ecosystem behaviour?
For example, we have a successful model emulating the behaviour of the Antarctic Silverfish (a nothothenioid), linked to a physical model of the water column. This is helping explain why smaller Silverfish occur in deeper waters and larger ones in shallower waters. For the Southern Ocean, these modelling approaches are still in their relative infancy. Working together with international colleagues, we are trying to develop that capacity further.
By: Richard de Ferranti
