Photobiological Effects on Ice Algae of a Rapid Whole-Fjord Loss of Snow Cover during Spring Growth in Kangerlussuaq, a West Greenland Fjord

Journal of Marine Science and Engineering

Lars Chresten Lund-Hansen¹  Brian K. Sorrell¹  Ian Hawes²  Tanja Stratmann³ 

[1] Arctic Research Centre, Department of Biology, Aarhus University, Aarhus C., DK-8000 Aarhus, Denmark;Coastal Marine Field Station, Environmental Research Institute, University of Waikato, Sulphur Point, Tauranga 3110, New Zealand;Department of Earth Sciences, Utrecht University, 3584 CB Utrecht, The Netherlands;

关键词: ice algae;    Greenland;    optics;    photobiology;    snow cover;    stress;   

DOI  :  10.3390/jmse9080814

来源: DOAJ

【 摘 要 】

Snow cover on sea ice is the most important factor controlling light availability for sea ice algae, but it is predicted by climate models to become more variable and stochastic. Here, we document effects of a sudden, complete loss of the entire snow cover on first-year sea ice at Kangerlussuaq Fjord, West Greenland, due to a natural Föhn wind event that caused a ca. 17 °C air temperature increase over 36 h. We applied Imaging-PAM fluorometry to examine effects of snow cover on algal distribution and photobiology and observed a rapid decrease in algal biomass associated with loss of the skeletal ice crystal layer on the underside of the ice that had supported most of the visible algae. Furthermore, the remaining algae were photobiologically stressed, as seen in a significant decrease in the dark-acclimated fluorescence yield (Φ_{PSII_max}) from 0.55 before snow loss to 0.41 after. However, recovery in the dark suggested that non-photosynthetic quenching was successfully dissipating excess energy in the community and that there was little photodamage. An observed decrease in the photosynthetic efficiency α from 0.22 to 0.16 µmol é m⁻² s⁻¹ is therefore likely to be due to photoacclimation and the change in community composition. Centric diatoms and flagellates were the main taxa lost in the snow loss event, whereas the sea ice specialist Nitzschia frigida increased in numbers. These observations are similar to those seen in artificial snow-clearing experiments and consistent with snow clearing being a useful approach for investigating the complex interactions between snow cover, irradiance fluctuations, and ice algal performance.

【 授权许可】

Unknown