The physiological response to increased temperature in over-wintering sea ice algae and phytoplankton in McMurdo Sound, Antarctica and Tromsø Sound, Norway

• Published in: Journal of Experimental Marine Biology and Ecology
• Main Authors: Martin, A, McMinn, A, Heath, M, Hegseth, EN, Ryan, KG
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier Science Bv 2012
• Subjects: Biological Sciences; Ecology; Marine and Estuarine Ecology (incl. Marine Ichthyology); Antarctic; Arctic; McMurdo Sound; Norway; Tromsø; Antarc*; Antarctica; ice algae; Phytoplankton; Sea ice; Troms
• Online Access: https://doi.org/10.1016/j.jembe.2012.06.006; http://ecite.utas.edu.au/79227

The physiological response to increased temperature during dark exposure was examined in phytoplankton and sea ice algae that had overwintered in McMurdo Sound, Antarctica and Troms Sound, Norway. Under ice phytoplankton and sea ice algae from McMurdo Sound were incubated in the dark for 22days and 23days respectively at −2, 4 and 10C, while phytoplankton from Troms Sound were incubated for 35days at 4, 10 and 20C. A fluorescence approach was used to examine algal photophysiology (Fv/Fm, rETRmax and α) and changes in the concentration of chlorophyll a , while the spectrophotometric 2,4,6-tripyridyl- s -triazine (TPTZ) assay was used to quantify water-extractable carbohydrates. Prior to incubation, the photosynthetic parameters documented relatively healthy overwintering communities for both polar regions. Elevated temperature had a considerable impact on the dark survival of Arctic phytoplankton, and, to a lesser extent, Antarctic sea ice algae: photosynthetic health and stored monosaccharides declined during the incubation period, particularly at the warmest temperature regimes. In contrast, the concentration of chlorophyll a and polysaccharides remained relatively constant. When Antarctic sea ice algae were subsequently exposed to low light (~20μmol photons m −2 s −1 ), significant photosynthetic recovery was only observed in cultures maintained at −2C. A more robust response to increased temperature was observed in Antarctic phytoplankton and in general, variability between the −2C and 4C (Antarctic) and 4C and 10C (Arctic) temperature regimes was minimal, which suggests that increasing temperature will not limit the ability of phytoplankton to survive the polar winter and provide the inocula for bloom events.