Journal Article

Increased pCO sub(2) and temperature reveal ecotypic differences in growth and photosynthetic performance of temperate and Arctic populations of Saccharina latissima

Wiencke, Christian, Iniguez, Concepcion, Olischlaeger, Mark, Gordillo, Francisco Javier Lopez, Koch, Kristina

2017

Overview

The Arctic population of the kelp Saccharina latissima differs from the Helgoland population in its sensitivity to changing temperature and CO sub( 2 ) levels. 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 CO sub(2) (380, 800, and 1500 mu atm pCO sub(2)) and temperature levels (SP population: 4, 10 degree C; HL population: 10, 17 degree C) on the photophysiology (O sub(2) production, pigment composition, D1-protein content) and carbon assimilation [Rubisco content, carbon concentrating mechanisms (CCMs), growth rate] of both ecotypes. Elevated temperatures stimulated O sub(2) production in both populations, and also led to an increase in pigment content and a deactivation of CCMs, as indicated by super(13)C isotopic discrimination of algal biomass ( epsilon sub(p)) in the HL population, which was not observed in SP thalli. In general, pCO sub(2) effects were less pronounced than temperature effects. High pCO sub(2) deactivated 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 pCO sub(2) and higher temperatures and it remained unchanged in the HL population. Ecotypic differentiation was revealed by a significantly higher O sub(2) production 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.

• Subject: Saccharina latissima