35. Evolutionary rescue from ocean acidification?

Peter Thor (1)*, Allison Bailey (1), Sam Dupont (2), Piero Calosi (3), Pierre De Wit (4), Torkel Gissel Nielsen (5), Janne Søreide (6), Haakon Hop (1)

1 Norwegian Polar Institute, Framcentre, Tromsø, NO-9296, Norway
2 University of Gothenburg, Dept. of Marine Sciences – Kristineberg, Fiskebäckskil, SE-451 78, Sweden
3 University of Quebec, Rimouski, QC G5L 3A1, Canada
4 University of Gothenburg, Dept. of Marine Sciences – Tjärnö, Strömstad, SE-452 96, Sweden
5 Danish Technical University, DTU-Aqua, Charlottenlund, DK-2920, Denmark
6 University Centre in Svalbard, Longyearbyen, NO-9171, Norway

Background
Animals’ ability to counter effects of ocean acidification (OA) will be enhanced by any present day adaptations to local environments in different geographic regions. Such differences in local adaptation may enable separated populations to complement each other if affected populations are re-populated from neighbouring populations.

Methods
pH reaction norms (pH 8.2 to 7.0) of prey ingestion rate, metabolic rate, as well as gene expression (investigated by transcriptomics analysis) were established and compared among three geographically isolated populations of the pelagic copepod Calanus glacialis.

Findings
Populations from Kongsfjorden and Billefjorden (Svalbard) seemed more severely affected by decreasing pH than the population from Disko Bay (Davis Strait). While individuals from Svalbard showed significant pH reaction norms of ingestion rate and metabolic rate, individuals from the Disko Bay were comparably unaffected. These differences related to genetic distance and transcriptome dissimilarities among the three populations.

Conclusions
Geographically isolated Arctic copepod populations of C. glacialis are genetically seperated. This extant separation allow differentiated responses to OA. Repopulation by Davis Strait C. glacialis could alleviate severe effects of OA in the Svalbard area.