title: Increased pCO2and temperature reveal ecotypic differences in growth and photosynthetic performance of temperate and Arctic populations of Saccharina latissima.
abstract: The Arctic population of the kelp Saccharina latissima differs from the Helgoland population in its sensitivity to changing temperature and CO2levels. The Arctic population does more likely benefit from the upcoming environmental scenario than its Atlantic counterpart. The previous research demonstrated that warming and ocean acidification (OA) affect the biochemical composition of Arctic (Spitsbergen; SP) and cold-temperate (Helgoland; HL) Saccharina latissima differently, suggesting ecotypic differentiation. This study analyses the responses to different partial pressures of CO2(380, 800, and 1500 µatm pCO2) and temperature levels (SP population: 4, 10 °C; HL population: 10, 17 °C) on the photophysiology (O2production, pigment composition, D1-protein content) and carbon assimilation [Rubisco content, carbon concentrating mechanisms (CCMs), growth rate] of both ecotypes. Elevated temperatures stimulated O2production in both populations, and also led to an increase in pigment content and a deactivation of CCMs, as indicated by13C isotopic discrimination of algal biomass (εp) in the HL population, which was not observed in SP thalli. In general, pCO2effects were less pronounced than temperature effects. High pCO2deactivated CCMs in both populations and produced a decrease in the Rubisco content of HL thalli, while it was unaltered in SP population. As a result, the growth rate of the Arctic ecotype increased at elevated pCO2and higher temperatures and it remained unchanged in the HL population. Ecotypic differentiation was revealed by a significantly higher O2production rate and an increase in Chl a, Rubisco, and D1 protein content in SP thalli, but a lower growth rate, in comparison to the HL population. We conclude that both populations differ in their sensitivity to changing temperatures and OA and that the Arctic population is more likely to benefit from the upcoming environmental scenario than its Atlantic counterpart.
authors.affiliation: Department of Functional Ecology, Alfred-Wegener-Institute, Helmholtz Center for Marine and Polar Research, Am Handelshafen 12, 27570, Bremerhaven, Germany. Mark.Olischlaeger@awi.de.
authors.forename: Mark
authors.identifier: http://orcid.org/0000-0003-4004-0819
authors.initials: M
authors.lastname: Olischläger
authors.affiliation: Department of Ecology, Faculty of Sciences, University of Malaga, Bulevar Louis Pasteur s/n, 29010, Malaga, Spain.
authors.forename: Concepción
authors.initials: C
authors.lastname: Iñiguez
authors.affiliation: Marine Botany and Bremen Marine Ecology-Center for Research and Education (BreMarE), University of Bremen, LeobenerStr. NW2, 28359, Bremen, Germany.
authors.forename: Kristina
authors.initials: K
authors.lastname: Koch
authors.affiliation: Department of Functional Ecology, Alfred-Wegener-Institute, Helmholtz Center for Marine and Polar Research, Am Handelshafen 12, 27570, Bremerhaven, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Wiencke
authors.affiliation: Department of Ecology, Faculty of Sciences, University of Malaga, Bulevar Louis Pasteur s/n, 29010, Malaga, Spain.
authors.forename: Francisco Javier López
authors.initials: FJ
authors.lastname: Gordillo
mesh_terms: D001110:Arctic Regions; D002245:Carbon Dioxide / Q000494:pharmacology*; D060146:Ecotype; D010313:Partial Pressure; D000459:Phaeophyceae / Q000187:drug effects / Q000254:growth & development* / Q000502:physiology*; D010788:Photosynthesis / Q000187:drug effects*; D010860:Pigments, Biological / Q000378:metabolism; D013696:Temperature
chemical_list: D010860:Pigments, Biological; D002245:Carbon Dioxide
keywords: Arctic; Carbon concentrating mechanisms; Kelp; Ocean acidification; Photosynthesis; Pigment; Seaweed