Cellular metabolism of different life stages of marine teleosts during Ocean Acidification and Warming

• Main Author: Leo, Elettra
• Other Authors: Sokolova, Inna, Poertner, Hans-Otto, Mark, Felix C.
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Universität Bremen 2021
• Subjects: ocean acidification and warming; mitochondrial respiration; fish; embryos; 570; 570 Life sciences; biology; ddc:570; Arctic; Svalbard; Øresund; Arctic Population; atlantic cod; Boreogadus saida; Gadus morhua; Ocean acidification; polar cod
• Online Access: https://media.suub.uni-bremen.de/handle/elib/5264; https://doi.org/10.26092/elib/1060; https://nbn-resolving.org/urn:nbn:de:gbv:46-elib52645

The anthropogenic emissions of greenhouse gases are causing an increase in atmospheric and oceanic temperatures. In the oceans, seawater temperature rises in parallel to the decrease in pH caused by the reaction of rising atmospheric CO2 with water. The combined phenomenon is known as Ocean Acidification and Warming (OAW). Rising temperatures and decreased water pH may induce adjustments in the energy budget of fish, requiring more energy for protein turnover and for ion and acid-base balance. Since most of these processes depend on the mitochondrial provision of ATP, this PhD project investigated if rising temperature and PCO2 affect the mitochondrial functioning with consequences for the energy budget and acclimation potential of the animals to climate changes. Mitochondria are specialised cellular organelles and their degree of specialisation may vary according to species and life-stage. To cover a broad range of this variability, this thesis analysed firstly the mitochondria of juvenile polar cod (Boreogadus saida) as polar fish and of juvenile Atlantic cod (Gadus morhua) from the Northeast Arctic population (NEAC) as temperate fish, which presently co- occur in the waters around Svalbard. Secondly, the mitochondria of juvenile NEAC were compared with the mitochondria of embryos of the same species (Øresund population) to assess the differences between life-stages. Lastly, mitochondria of Atlantic cod embryos were analysed together with the ones of Atlantic herring embryos (Clupea harengus) because of the different spawning behaviour of the two species (pelagic for Atlantic cod, benthic for herring). Polar cod and NEAC were acclimated for four months at combinations of temperature (polar cod: 0, 3, 6, 8°C; NEAC: 3, 8, 12, 16°C) and PCO2 (400 and 1170 μatm) at the end of which their cardiac mitochondrial respiration was tested. In addition, the lipid class composition in pooled cellular membranes and the capacity of a number of mitochondrial enzymes were analysed. Embryos of Atlantic cod and herring were ...