Temperate and cold water sea urchin species in an acidifying world: coping with change?

• Main Author: Dos Ramos Catarino, Ana Isabel
• Other Authors: De Ridder, Chantal, Dubois, Philippe, Chou, Lei, Josens, Guy, Allemand, Denis, Grosjean, Philippe
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: Universite Libre de Bruxelles 2011
• Subjects: Biologie; Sciences exactes et naturelles; Chemical oceanography; Sea-urchins > Effect of water acidification on; Water acidification; Océanographie chimique; Oursins; Effets de l'acidification de l'eau sur les; Eau > Acidification; adult; larvae; acid base balance; calcification; physiology; sea urchin; Ocean acidification
• Online Access: http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209914; https://dipot.ulb.ac.be/dspace/bitstream/2013/209914/1/0d0f2a26-9e7d-4c61-9238-598146e99231.txt; https://dipot.ulb.ac.be/dspace/bitstream/2013/209914/4/9e184a11-7315-4d91-872f-28473111c161.txt

Anthropogenic carbon dioxide (CO2) emissions are increasing the atmospheric CO2 concentration and the oceans are absorbing around 1/3 them. The CO2 hydrolysis increases the H+ concentration, decreasing the pH, while the proportions of the HCO3- and CO32- ions are also affected. This process already led to a decrease of 0.1 pH units in surface seawater. According to "business-as-usual" models, provided by the Intergovernmental Panel on Climate Change (IPCC), the pH is expected to decrease 0.3-0.5 units by 2100 and 0.7-0.8 by 2300. As a result the surface ocean carbonates chemistry will also change: with increasing pCO2, dissolved inorganic carbon will increase and the equilibrium of the carbonate system will shift to higher CO2 and HCO3– levels, while CO32– concentration will decrease. Surface seawaters will progressively become less saturated towards calcite and aragonite saturation state and some particular polar and cold water regions could even become completely undersaturated within the next 50 years. Responses of marine organisms to environmental hypercapnia, i.e. to an excess of CO2 in the aquatic environment, can be extremely variable and the degree of sensitivity varies between species and life stages. Sea urchins are key stone species in many marine ecosystems. They are considered to be particularly vulnerable to ocean acidification effects not only due to the nature of their skeleton (magnesium calcite) whose solubility is similar or higher than that of aragonite, but also because they lack an efficient ion regulatory machinery, being therefore considered poor acid-base regulators. Populations from polar regions are expected to be at an even higher risk since the carbonate chemical changes in surface ocean waters are happening there at a faster rate. The goal of this work was to study the effects of low seawater pH exposure of different life stages of sea urchins, in order to better understand how species from different environments and/or geographic origins would respond and if there would be scope ...