title: Ocean acidification modulates the response of two Arctic kelps to ultraviolet radiation.
abstract: The combined effects of ocean acidification and ultraviolet radiation (UVR) have been studied in the kelps Alaria esculenta and Saccharina latissima from Kongsfjorden (Svalbard), two major components of the Arctic macroalgal community, in order to assess their potential to thrive in a changing environment. Overall results revealed synergistic effects, however with a different amplitude in the respective species. Changes in growth, internal N, C:N ratio, pigments, optimum quantum yield (Fv/Fm) and electron transport rates (ETR) following CO2 enrichment and/or UVR were generally more pronounced in S. latissima than in A. esculenta. The highest growth rates were recorded under simultaneous CO2 enrichment and UVR in both species. UVR-mediated changes in pigment content were partially prevented under elevated CO2 in both species. Similarly, UVR led to increased photosynthetic efficiency (α) and ETR only if CO2 was not elevated in A. esculenta and even under high CO2 in S. latissima. Increased CO2 did not inhibit external carbonic anhydrase (eCA) activity in the short-term but in the mid-term, indicating a control through acclimation of photosynthesis rather than a direct inhibition of eCA by CO2. The higher benefit of simultaneous CO2 enrichment and UVR for S. latissima respect to A. esculenta seems to involve higher C and N assimilation efficiency, as well as higher ETR, despite a more sensitive Fv/Fm. The differential responses shown by these two species indicate that ongoing ocean acidification and UVR could potentially change the dominance at lower depths (4-6m), which will eventually drive changes at the community level in the Arctic coastal ecosystem. These results support an existing consideration of S. latissima as a winner species in the global change scenario.
authors.affiliation: Departamento de Ecología, Facultad de Ciencias, Universidad de Málaga, Bulevar Louis Pasteur s/n, 29010 Málaga, Spain. Electronic address: gordillo@uma.es.
authors.forename: Francisco J L
authors.initials: FJ
authors.lastname: Gordillo
authors.affiliation: Departamento de Dermatología, Facultad de Medicina, Universidad de Málaga, Bulevar Louis Pasteur s/n, 29010 Málaga, Spain.
authors.forename: José
authors.initials: J
authors.lastname: Aguilera
authors.affiliation: Alfred Wegener Institute, Am Handelshafen 12, D-27570 Bremerhaven, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Wiencke
authors.affiliation: Departamento de Ecología, Facultad de Ciencias, Universidad de Málaga, Bulevar Louis Pasteur s/n, 29010 Málaga, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: Jiménez
mesh_terms: D000064:Acclimatization; D002244:Carbon / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism*; D017753:Ecosystem; D004579:Electron Transport / Q000528:radiation effects; D006863:Hydrogen-Ion Concentration; D009584:Nitrogen / Q000378:metabolism; D009792:Oceans and Seas; D000459:Phaeophyceae / Q000254:growth & development / Q000502:physiology* / Q000528:radiation effects; D010788:Photosynthesis / Q000528:radiation effects*; D013045:Species Specificity; D014466:Ultraviolet Rays
chemical_list: D002245:Carbon Dioxide; D002244:Carbon; D009584:Nitrogen
keywords: Alaria esculenta; Arctic; Ocean acidification; Saccharina latissima; Ultraviolet radiation