Büdenbender, Jan (2009) Impacts of ocean acidification on the calcification of arctic coralline red algae (Lithothamnion spec.). (Diploma thesis), Christian-Albrechts-Universität zu Kiel, Kiel, Germany, 90 pp.

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Abstract

The present anthropogenic C02 production causes an acidification of the world's oceans. Experimental evidence showes that ocean acidification induced effects in the water chemistry inhibit biogenic calcification. The here presented work focuses on ocean acidification effects on Arctic coralline red algal calcification, a vital process for algal growth and survival. Coralline red algae are very abundant organisms in both Polar Regions and are important as habitat provider for the local ecosystem. Future development of coralline algal calcification rates was studied on the coralline red alga Lithothamnion tophiforme in laboratory experiments simulating predicted atmospheric C02 concentrations. Since the Arctic provides extreme conditions due to a highly seasonal annual light-cycle to photosynthetic organisms, experiments imaged Arctic summer and winter conditions separately. Ocean acidification was simulated through increasing the C02 concentration in the supplied air with gas mixing pumps. Experiments showed a significant effect on calcification rates of Lithothamnion tophiforme by ocean acidification. At elevated pC02 levels, calcification was reduced in all experiments. Net dissolution of CaC03 was measured at a pC02 of 980 respectively 1880 ppm during the "winter" and "summer" experiment. Furthermore, a low annual CaC03 production rate of 235 - 391 g CaC03 m-2 y-1 and a during four weeks ongoing dark calcification are shown in this work.

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