Contrasting physiological responses to future ocean acidification among Arctic copepod populations

Abstract

Widespread ocean acidification (OA) is modifying the chemistry of the global ocean, and the Arctic is recognized as the region where the changes will progress at the fastest rate. Moreover, Arctic species show lower capacity for cellular homeostasis and acid-base regulation rendering them particularly vulnerable to OA. In the present study, we found physiological differences in OA response across geographically separated populations of the keystone Arctic copepod Calanus glacialis. In copepodites stage CIV, measured reaction norms of ingestion rate and metabolic rate showed severe reductions in ingestion and increased metabolic expenses in two populations from Svalbard (Kongsfjord and Billefjord) whereas no effects were observed in a population from the Disko Bay, West Greenland. At pH T 7.87, which has been predicted for the Svalbard west coast by year 2100, these changes resulted in reductions in scope for growth of 19% in the Kongsfjord and a staggering 50% in the Billefjord. Interestingly, these effects were not observed in stage CV copepodites from any of the three locations. It seems that CVs may be more tolerant to OA perhaps due to a general physiological reorganization to meet low intracellular pH during hibernation. Needless to say, the observed changes in the CIV stage will have serious implications for the C. glacialis population health status and growth around Svalbard. However, OA tolerant populations such as the one in the Disko Bay could help to alleviate severe effects in C. glacialis as a species. K E Y W O R D SArctic, ingestion rate, metabolic rate, ocean acidification, pCO2, pH, reaction norm, zooplankton

Effects of Elevated CO2 on a Natural Diatom Community in the Subtropical NE Atlantic

“…Such experiments exist for Temora longicornis but it is unclear whether the Temora species in our experiments would show the same insensitivity to high CO 2 as the individuals from the English Channel investigated by McConville et al (2013). Recent OA experiments with Calanus glacialis revealed population-specific CO 2 responses with more robust populations found in naturally CO 2 -rich habitats (Thor et al, 2018). These findings suggest that local carbonate chemistry conditions may be a better predictor to assess CO 2 sensitivities of copepods than their taxonomic affiliation (Thor et al, 2018;Zhang et al, 2018).…”

“…Recent OA experiments with Calanus glacialis revealed population-specific CO 2 responses with more robust populations found in naturally CO 2 -rich habitats (Thor et al, 2018). These findings suggest that local carbonate chemistry conditions may be a better predictor to assess CO 2 sensitivities of copepods than their taxonomic affiliation (Thor et al, 2018;Zhang et al, 2018). They also suggest that laboratory-based results can only reliably be used to interpret responses observed in experiments with natural assemblages when both experiments were done with individuals from the same population.…”

Pelagic Ecosystem Characteristics Across the Atlantic Water Boundary Current From Rijpfjorden, Svalbard, to the Arctic Ocean During Summer (2010–2014)

“…Weydmann et al (2012) also found that CO 2 -induced seawater acidification had no significant effect on egg production of C. glacialis. However, Thor et al (2018a) detected negative effects of OA on scope for growth in C. glacialis copepodid stage IV at pH 7.87, and Weydmann et al (2012) noted delayed hatching and possibly reduced overall hatching success for this species at lower pH of 6.9. Opstad et al (2018) showed little effect of ocean acidification (high CO 2 levels, low pH) on the northern krill T. inermis.…”

Impacts of the Changing Ocean-Sea Ice System on the Key Forage Fish Arctic Cod (Boreogadus Saida) and Subsistence Fisheries in the Western Canadian Arctic—Evaluating Linked Climate, Ecosystem and Economic (CEE) Models

“…E.g., Arctic pteropods are suggested to be negatively impacted by temperature and ocean acidification (Comeau et al, 2010(Comeau et al, , 2012Bednaršek et al, 2012;Lischka and Riebesell, 2012) and for the Arctic copepod Calanus glacialis ocean acidification effects seem to vary with developmental stage. Earlier copepodite stages show increases in metabolic rates and decreased scope for growth at high pCO 2 levels (Thor et al, 2017).…”