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

DOI

The presence of snow on sea-ice can have dramatic effects on the photosynthetically available radiation (PAR) that reaches the ice algae. To better quantify this effect in the high Arctic, an experiment was conducted in Kangerlussuaq, west Greenland, throughout March 2013 where snow was cleared off the sea-ice and measured parameters were compared to a control area. Samples of under-ice algae were then taken to analyse the species composition. The bottom 30 mm of the sampled ice cores were used to determine the stress on the photosystems of the sea ice algae as they experienced the rapid irradiance via the variable fluorescence of photosystem II (PSII). PSII was measured using pulse amplitude modulated (PAM) fluorometry (Walz Imaging-PAM fluorometer). This provides the effective quantum yield of PSII (Φ_PSII), which is a unitless ratio of ambient (F) and maximum (F_m) fluorescence yields. These measurements were taken every 3 hours over the final day of the study. Periodically over the week of the study, similar measurements were taken (in triplicate) with a Phyto-PAM System II Emitter-Detector (Phyto-ED) to determine how F and F_m values changed at a courser temporal resolution. Also measured were rapid light curves (RLCs), which allowed for the derivation of the relative electron transfer rate (rETR and rETR_max; µmol é/m²/s), the slope of the light-limited portion of the RLC (α; mol é /mol photons), and the irradiance at which rETR was light-saturated (E_k; µmol photon/m²/s).100 ml samples of thawed sea-ice were also collected and stored in the dark to be used for species identification. This was done by first enumerating the ice algae to the Utermöhl method. A Zeiss Axiovert 135M (40×) inverted microscope was used to identify and count species/morphological groups via a total of four diagonals per sample. Relative abundances of algae were estimated as percent of total count, and the biomass was calculated according to the ALGESYS protocol.Throughout the experiment the following variables were collected at 5 minute intervals: Air temperature (°C; sun-screened Campbell 107 temperature probe), upwelling and downwelling PAR (µmol photons/m²s; Li-COR Li-191 PAR sensor) at 0.5 m above the sea-ice surface, and under-ice PAR (µmol photon/m²/s; Li-COR –Li-192 submersible PAR sensor). From these data, transmittance (τ) was calculated as the ratio between under-ice PAR and downwelling PAR at the surface, and albedo (0-1 scale) was calculated as the ratio between upwelling and downwelling PAR at the surface.

Identifier
DOI https://doi.org/10.1594/PANGAEA.963203
Related Identifier References https://doi.org/10.3390/jmse9080830
Related Identifier References https://doi.org/10.1594/PANGAEA.962926
Related Identifier References https://doi.org/10.1594/PANGAEA.962928
Related Identifier References https://doi.org/10.3390/jmse9080814
Metadata Access https://ws.pangaea.de/oai/provider?verb=GetRecord&metadataPrefix=datacite4&identifier=oai:pangaea.de:doi:10.1594/PANGAEA.963203
Provenance
Creator Sorrell, Brian K ORCID logo; Hawes, Ian ORCID logo; Stratmann, Tanja ORCID logo; Lund-Hansen, Lars Chresten (ORCID: 0000-0001-5925-322X)
Publisher PANGAEA
Publication Year 2023
Funding Reference Danish Council for Independent Research https://doi.org/10.13039/501100004836 Crossref Funder ID DFF - 1323-00335 ; Ministry of Business, Innovation and Employment https://doi.org/10.13039/501100003524 Crossref Funder ID ANTA1801
Rights Creative Commons Attribution 4.0 International; https://creativecommons.org/licenses/by/4.0/
OpenAccess true
Representation
Resource Type Bundled Publication of Datasets; Collection
Format application/zip
Size 4 datasets
Discipline Earth System Research
Spatial Coverage (-51.084 LON, 66.899 LAT); Greenland
Temporal Coverage Begin 2013-03-09T10:21:20Z
Temporal Coverage End 2013-03-19T17:35:00Z