As part of the Marie-Tharp Lecture Series of the Women’s Executive Board at GEOMAR, Prof. Antje Boetius of the Alfred Wegener Institute (AWI), Helmholtz Centre for Polar and Marine Research and the Max Planck Institute for Marine Microbiology in Bremen reported on her work on the impacts of climate change in the Arctic Ocean.
“It was very exciting in those days. We were explorers,” goes the familiar saying by oceanography pioneer Marie Tharp (1920-2006). But why “was”? And “were”? Even today the marine sciences are very exciting, and marine scientists are still real discoverers, as Prof. Antje Boetius from the Alfred Wegener Institute (AWI), Helmholtz Centre for Polar and Marine Research and the Max-Planck Institute for Marine Microbiology in Bremen knows from first-hand experience.
As part of the Marie-Tharp Lecture Series of the Women’s Executive Board at GEOMAR, the female German oceanographer with probably the most scientific awards reported on her work on the impacts of climate change in the Arctic Ocean. Her presentation in Kiel can be seen as a return to her roots: “Olaf Pfannkuche from GEOMAR selected me as a student assistant for my first METEOR expedition. Since then I have absolutely fallen in love with the work at sea,” the 47-year-old recalls.
During Antje Boetius’ latest Arctic journey, chain-forming ice algae created some excitement. Melosira arctica normally lives at the bottom of the ice floes. In coastal areas, where the ice is growing over several years, the diatoms can form several meters long strands.
“We found that Melosira was responsible for 45 percent of primary production in the central Arctic in 2012,” says Prof. Antje Boetius. There the ice is reproduced year after year – and with it the long strands of algae. At the seafloor, the researchers discovered a lot of Melosira clumps with a diameter of up to 50 centimeters. Only a few of them seemed to be eaten by sea cucumbers.
“It had to be a new food source that could not be processed by other organisms; otherwise there would have been a lot more going on,” concludes the microbiologist from Bremen. “But why do they sink down at all?” The reason for this could be an increased ice melt: More light penetrates through the ice and promotes the growth of algae. But with a thinning ice and warming water, the algae are more readily released from the ice and sink to the bottom of the deep sea – quite a rapid response of Arctic ecosystems to rising temperatures.
To determine whether this is really a new phenomenon, Prof. Boetius and some colleagues at the Alfred Wegener Institute now compare their new samples with historical samples from the Arctic before the big ice melt. In addition, the “discoverer” is already longing to go back to the pole.
“There are unexplored hydrothermal vents and a 4000-meter-high undersea volcano, with giant sponges on its slopes,” she says.