Ecophysiological responses of the cold-water coral Lophelia pertusa from the North Atlantic under projected future climate change conditions.

Büscher, Janina Vanessa (2012) Ecophysiological responses of the cold-water coral Lophelia pertusa from the North Atlantic under projected future climate change conditions. (Master thesis), Christian-Albrechts-Universität zu Kiel, Kiel, Germany, 86 pp.

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Abstract

The azooxanthellate scleractinian cold-water coral Lophelia pertusa is an abundant and widespread distributed coral that builds large reef-framework structures along the continental shelves. These huge and extended reefs are habitat and nursery grounds for a variety of organisms and, hence, form so-called biodiversity hot-spots. Ocean acidification caused by anthropogenic C02 uptake is projected to expose 70% of the presently known cold-water coral bioherms to waters corrosive for their carbonate structures by the end of this century, if C02 emissions proceed unabated. The oceans' surface temperature is expected to increase globally for about 3°C and there is growing evidence that the oceans are warming even in the deeper water layers between 700 and 3 000 m. Despite their critical role as bioengineers and importance as living environment for a diverse associated community, very little is known about the sensitivity of reef-building deep-sea scleractinians towards ocean acidification and global warming. This thesis comprises ecophysiological responses of Lophelia pertusa to climate change related future scenarios expected by 2100 in a short-term experiment. Samples of this species from the Scottish Mingulay Reef Complex were investigated with respect to respiration (oxygen consumption rates) and fitness (RNA/DNA ratios). Considering the simultaneous appearance of increasing carbon dioxide (C02) conditions and warming of the oceans, impacts were not only examined on separate, but also on the combined effect of both factors. The fitness was analysed fluorometrically by measuring the amount of RNA and DNA in the polyp. Short-term incubation under all treatment conditions led to decreased metabolic activity (protein biosynthesis) in the cells, where the pC02 had a more pronounced effect that seemed to have up-regulated under the additional influence of increased temperature. Respiration rates were measured using advanced optode technology and revealed an increase in all treatments after ten days of incubation compared to ambient conditions. An increase in temperature of + 3°C had the most severe impact on oxygen consumption, whereas under combined conditions the effect was less pronounced. Although L. pertusa is a rather good regulator, it was found that the respiratory regulation ability decreased significantly (~22 %) under elevated temperatures. These results indicate that although still negatively affected the interactive impact of enhanced C02 concentrations and elevated temperature appears not to be exacerbating but demonstrating the complexity of interactions of physiological processes.

Document Type: Thesis (Master thesis)
Subjects: Course of study: MSc Biological Oceanography
Research affiliation: OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-BI Biological Oceanography
Kiel University
Open Access Journal?: No
Date Deposited: 15 Jan 2013 12:30
Last Modified: 10 Jan 2022 08:08
URI: https://oceanrep.geomar.de/id/eprint/20122

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