Iron is Limiting Factor to Algal Growth in Antarctic Ocean

28-09-2012   The amount of dissolved iron in the surface water of some parts of the Antarctic Ocean is so small that it limits algal growth. In the Arctic Ocean, iron concentrations are higher due to the influence of rivers. Maarten Klunder measured iron concentrations in various parts and at various depths of the Arctic Ocean. In addition, he ascertained where the iron came from. On 5 October 2012, Klunder will defend his PhD thesis on this research project at the University of Groningen.

About 80 years ago, scientists began to suspect that dissolved iron might well be the limiting factor to algal growth in the polar oceans. In the following decades, this possible correlation was studied, but doing research in the polar regions is complicated and it is also quite complex to accurately measure such low iron concentrations; it was only in recent decades that more data became available.

Klunder has studied iron concentrations at various depths in the polar oceans since November 2006. He also studied the source of iron and the role iron plays in algal growth. Using new, advanced equipment for taking samples and making long transects with many sampling points, he painted a complete picture of iron concentrations and many new insights into the distribution of iron have been gained from this. Some information on the distribution and availability of iron in the oceans may already be known, but Klunder is the first to have systematically studied the amount of iron in three areas of the Antarctic and Arctic Oceans across the depth of the oceans.

Combining these data with other chemical and biological parameters, he could put the distribution, origin and decrease of iron in a wider context. His most important finding suggests that in some parts of the Antarctic Ocean the amount of dissolved iron is so small that it affects algal growth. The amount of iron in the Arctic Ocean is higher due to input from Siberian rivers. The influence of submarine volcanoes, which also supply iron, has now been recorded accurately and is stronger than expected.

The research cruises were made aboard the Polarstern in 2007 and 2008 as part of the International Polar Year. This research project was part of the IPY-GEOTRACES project and was funded by the Netherlands Organisation for Scientific Research (NWO), the Royal Netherlands Institute for Sea Research (NIOZ) and GEOTRACES.

Klunder (1980) studied Hydrology and Water Quality at Wageningen University. From November 2006 to May 2011 he was a PhD student at NIOZ. He is currently employed by CTGB in Wageningen.

www.geotraces.org/cruises/cruise-summary
Dissertation

Picture above: RV Polarstern.








A CTD water sampler (conductivity, temperature, depth) with ultra-clean sampling bottles.