Biological characteristics modulating the sensitivity of calcification under Ocean Acidification: A comparative approach in adult echinoderms
The uptake of CO2 by the ocean is causing major changes in its chemistry. These changes are likely to have detrimental effects on many organisms with a severe impact on calcifying species. With future OA, marine organisms will be submitted to hypercapnia (increased pCO2) and acidosis (decreased pH)....
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| Other Authors: | , , , , |
| Format: | Doctoral or Postdoctoral Thesis |
| Language: | English |
| Published: |
Universite Libre de Bruxelles
2020
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| Online Access: | http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/302980 https://dipot.ulb.ac.be/dspace/bitstream/2013/302980/7/ContratDiGiglio.pdf https://dipot.ulb.ac.be/dspace/bitstream/2013/302980/5/Di_Giglio_2020_Availableparts.pdf https://dipot.ulb.ac.be/dspace/bitstream/2013/302980/4/Di_Giglio_2020_CH_IV_Echinometra.pdf https://dipot.ulb.ac.be/dspace/bitstream/2013/302980/6/Table_of_content.pdf https://dipot.ulb.ac.be/dspace/bitstream/2013/302980/3/Di_Giglio_2020_CH_VI_Antarctica.pdf |
| Summary: | The uptake of CO2 by the ocean is causing major changes in its chemistry. These changes are likely to have detrimental effects on many organisms with a severe impact on calcifying species. With future OA, marine organisms will be submitted to hypercapnia (increased pCO2) and acidosis (decreased pH). Skeleton production and maintenance could be impacted due to the increased energetic cost to calcify in less favourable conditions and direct corrosive effect of undersaturated seawater resulting in dissolution of calcium-carbonate unprotected structures. Postmetamorphic echinoderms (juveniles and adults) endoskeleton is made of high magnesium-calcite, one of the most soluble form of CaCO3. Because of their low metabolism and their heavily calcified skeleton, echinoderms were designated as species particularly at risk under OA. However, the effects of OA on calcification and on skeleton maintenance vary among closely related taxa. Hypotheses explaining these contrasted tolerance to OA were stated: (1) regulation of the acid-base balance, which occurs in some echinoderms taxa and not others, plays a major role; (2) populations living in highly fluctuating habitats are adapted or selected, which may confer them a better resistance to acidified conditions. The goal of this thesis was to evaluate these hypotheses using a comparative approach in asteroids (two species) and regular euechinoids (five species). The chosen species differ by their ability to regulate their acid-base physiology and by the amplitude of fluctuations in their habitats. The impacts of OA on corrosion and mechanical properties of their skeletal elements as well as, in selected species, the expression of biomineralization-related genes were investigated. All samples were obtained from individuals exposed to acidified conditions during long-term aquarium experiments or in situ exposures (CO2 vents).Bending and compression mechanical tests analysed by Weibull statistics and expression of biomineralization-related genes appeared particularly unitive ... |
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