Impact of ocean acidification and elevated temperatures on early juveniles of the polar shelled pteropod iLimacina helicina/i: mortality, shell degradation, and shell growth

摘要

Due to their aragonitic shell, thecosome pteropods may be particularlyvulnerable to ocean acidification driven by anthropogenic CO₂emissions. This applies specifically to species inhabiting Arctic surfacewaters that are projected to become temporarily and locally undersaturatedwith respect to aragonite as early as 2016. This study investigated theeffects of rising partial pressure of CO₂ (pCO₂) and elevatedtemperature on pre-winter juveniles of the polar pteropod Limacina helicina. After a 29 dayexperiment in September/October 2009 at three different temperatures and underpCO₂ scenarios projected for this century, mortality, shell degradation,shell diameter and shell increment were investigated. Temperature andpCO₂ had a significant effect on mortality, but temperature was theoverriding factor. Shell diameter, shell increment and shell degradationwere significantly impacted by pCO₂ but not by temperature. Mortalitywas 46% higher at 8 °C than at in situ temperature (3 °C), and 14%higher at 1100 μatm than at 230 μatm. Shell diameter and incrementwere reduced by 10 and 12% at 1100 μatm and 230 μatm,respectively, and shell degradation was 41% higher at elevated comparedto ambient pCO₂. We conclude that pre-winter juveniles will benegatively affected by both rising temperature and pCO₂ which may resultin a possible decline in abundance of the overwintering population, thebasis for next year's reproduction.