Trans-life Cycle Impacts of Ocean Acidification on the Green Sea Urchin Strongylocentrotus droebachiensis
This thesis studies the impacts of ocean acidification on an ecologically and economically important invertebrate of the Nordic waters: the green sea urchin Strongylocentrotus droebachiensis. Acidification affects the different life stages and transitions composing the life-cycle. Paper I establishes the robustness of the larval stage to a broad range of acidification (-1.5 pHT units) covering present, projected near-future variability and beyond. Development of normal, although showing morphological plasticity, swimming larvae was possible as low as pHT ≥ 7.0. Acidification increased mortality and respiration and decreased growth rate. Paper II focuses on the impacts of a decreased pH (-0.4 and -0.8 units) on the transitions phases between the larval and juvenile stages and on juveniles’ survival. Lowered pH induced both direct effects of (e.g. juvenile spine amount) and carry-over effects (e.g. increased settlement rates). Paper III deals with juvenile and adult stages. While adult fecundity was reduced after a 4-months exposure to low pH (-0.4 units), it was not affected anymore after 16-months. On the other hand, juveniles experienced a 95% mortality when grown at low pH since fertilization. Paper IV is a meta-analysis based on the available experimental data available on echinoderms in 2010 revealing differing sensitivities of the stages and processes studied to near-future predictions. Paper V reveals, from in vivo measurements on S. droebachiensis pluteus larvae, that the extracellular compartment surrounding the calcifying cells conforms to the surrounding seawater with respect to pH. Under ocean acidification, maintaining constant intracellular pH for calcium precipitation probably causes enhanced metabolic costs.
Parts of work
I. Dorey N, Lançon P, Thorndyke M & Dupont S (2013) Assessing physiological tipping point of sea urchin larvae exposed to a broad range of pH. Global Change Biology ::doi::10.1111/gcb.12276II. Dorey N, Butera E & Dupont S (manuscript) Ocean acidification affects transition between life-history stages in sea urchin.III. Dupont S, Dorey N, Stumpp M, Melzner F & Thorndyke MC (2012) Long-term and trans-life-cycle effects of exposure to ocean acidification in the green sea urchin Strongylocentrotus droebachiensis. Marine Biology, 160 (8), 1835- 1843 ::doi::10.1007/s00227-012-1921-xIV. Dupont S, Dorey N & Thorndyke MC (2010) What meta-analysis can tell us about vulnerability of marine biodiversity to ocean acidification? Estuarine, Coastal and Shelf Science: 89, 182–185 ::doi::10.1016/j.ecss.2010.06.013V. Stumpp M, Hu MY, Melzner F, Gutowska MA, Dorey N, Himmerkus N, Holtmann WC, Dupont S, Thorndyke MC & Bleich M (2012) Acidified seawater impacts sea urchin larvae pH regulatory systems relevant for calcification. Proceedings of the National Academy of Sciences of the United States of America, 109, 18192–7 ::doi::10.1073/pnas.1209174109
Doctor of Philosophy
University of Gothenburg. Faculty of Science
Department of Biological and Environmental Sciences ; Institutionen för biologi och miljövetenskap
fredag den 04 oktober 2013 kl. 10:30 i Hörsalen, Institutionen för biologi och miljövetenskap, Sven Lovèn Centrum för marina vetenskaper, Kristineberg, Fiskebäckskil.
Date of defence