Differential acclimation responses to irradiance and temperature in two co-occurring seaweed species in Arctic fjords

• Published in: Polar Research
• Main Authors: Marambio, Johanna, Bischof, Kai
• Format: Article in Journal/Newspaper
• Language: English
• Published: Norwegian Polar Institute 2021
• Subjects: Arctic; Desmarestia aculeata; Palmaria palmata; photosynthesis; temperature; irradiance; Svalbard; Kongsfjord*; Kongsfjorden; North Atlantic; Polar Research; Sea ice
• Online Access: https://polarresearch.net/index.php/polar/article/view/5702; https://doi.org/10.33265/polar.v40.5702

Arctic fjord systems experience large amplitudes of change in temperature and radiation regime due to climate warming and the related decrease in sea ice. The resultant increase in irradiance entering the water column influences photosynthetic activity of benthic and pelagic primary producers. The subtidal brown algaDesmarestia aculeataand the intertidal red algaPalmaria palmatapopulate the cold-temperate coasts of the North Atlantic, reaching the polar zone. To evaluate their acclimation potential, we collected both species in Kongsfjorden, Svalbard (78.9°N, 11.9°E), during the Arctic summer and exposed specimens to two different PAR levels (50 and 500 μmol photons m−2s−1) and temperatures (0, 4 and 8 °C) for 21 days. Photosynthetic parameters and biochemical features (pigment concentration and antioxidants) were assessed. In general, high irradiance was the factor that generated a negative effect forD. aculeataandP. palmatain the photosynthetic parameters of the photosynthesis–irradiance curve andFv/Fm. The pigment concentration in both species tended to decrease with increasing irradiance. Antioxidant level showed different trends for both species: inD. aculeata, antioxidant potential increased with high irradiance and temperature, while inP. palmata, it only increased with high irradiance. Both species showed responses to the interaction of irradiance and temperature, althoughD. aculeatawas more sensitive to high irradiance thanP. palmata. Our study shows how these species, which have similar geographical distribution in the North Atlantic and the Arctic but belong to different taxonomic lineages, have similar strategies of acclimation, although they respond differently to ecophysiological parameters.