Contrasting Ice Algae and Snow‐Dependent Irradiance Relationships Between First‐Year and Multiyear Sea Ice. Issue 19 (10th October 2019)

• Record Type: Journal Article
• Authors: Lange, Benjamin A.; Haas, Christian; Charette, Joannie; Katlein, Christian; Campbell, Karley; Duerksen, Steve; Coupel, Pierre; Anhaus, Philipp; Jutila, Arttu; Tremblay, Pascal O. G.; Carlyle, Cody G.; Michel, Christine
• Is Part Of: Geophysical research letters. Volume 46:Issue 19(2019)
• Page Start: 10834
• Page End: 10843
• Publication Date: 2019-10-10
• Subjects: sea ice algae -- sea ice biophysics -- multiyear sea ice -- first year sea ice -- Last Ice Area -- climate change; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2019GL082873
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: During the 2018 Multidisciplinary Arctic Program‐Last Ice in the Lincoln Sea, we sampled 45 multiyear ice (MYI) and 34 first‐year ice (FYI) cores, combined with snow depth, ice thickness, and transmittance surveys from adjacent level FYI and undeformed MYI. FYI sites show a decoupling between bottom‐ice chlorophyll a (chl a) and snow depth; however, MYI showed a significant correlation between ice‐algal chl a biomass and snow depth. Topographic control of the snow cover resulted in greater spatiotemporal variability of the snow over the level FYI, and consequently transmittance, compared to MYI with an undulating surface. The coupled patterns of snow depth, transmittance, and chl a indicate that MYI provides an environment with more stable light conditions for ice algal growth. The importance of sea ice surface topography for ice algal habitat underpins the potential ecological changes associated with projected increased ice dynamics and deformation. Plain Language Summary: This study presents first results from the 2018 Multidisciplinary Arctic Program‐Last Ice, the most intensive ecologically focused research project ever conducted within the so‐called "Last Ice Area." This region is of key importance because it is the only place in the Arctic expected to retain summer sea ice by the year 2050. Continued changes to the sea ice environment will have ecological consequences because sea ice is an important habitat for many animals from microscopic ice algae, the base of the food chain, to seals and polar bears. Since the older ice is being replaced by younger ice, we compared older ice to younger ice in order to provide a glimpse into the future. We found that the older ice has a more stable light environment for ice algae due to snow depth patterns associated with surface topography. This can mean that as the older ice is replaced by newer ice, the availability of ice algae as a food source may become more unpredictable. The importance of surface topography for ice algae indicates that the projected acceleration in sea ice drift and increased ridging due to thinner ice will likely have an impact on key sea ice habitat properties. Key Points: Spatiotemporal changes in snow cover and transmittance were observed for FYI but remained stable for MYI due to differences in topography The spatial distribution of bottom‐ice chl a biomass was coupled to snow depth and transmittance in MYI but decoupled in FYI A projected shift to a more dynamic and deformed sea ice cover is likely to be a key driver of ice‐algal habitat variability in the future