Publication Date:
2018-01-11
Description:
Assessing the role of sea ice algal biomass and primary production for polar ecosystems
remains challenging due to the strong spatio-temporal variability of sea ice algae.
Therefore, the spatial representativeness of sea ice algal biomass and primary production
sampling remains a key issue in large-scale models and climate change predictions
of polar ecosystems. To address this issue, we presented two novel approaches to
up-scale ice algal chl a biomass and net primary production (NPP) estimates based
on profiles covering distances of 100 to 1,000 s of meters. This was accomplished
by combining ice core-based methods with horizontal under-ice spectral radiation
profiling conducted in the central Arctic Ocean during summer 2012. We conducted
a multi-scale comparison of ice-core based ice algal chl a biomass with two profiling
platforms: a remotely operated vehicle and surface and under ice trawl (SUIT). NPP
estimates were compared between ice cores and remotely operated vehicle surveys.
Our results showed that ice core-based estimates of ice algal chl a biomass and NPP
do not representatively capture the spatial variability compared to the remotely operated
vehicle-based estimates, implying considerable uncertainties for pan-Arctic estimates
based on ice core observations alone. Grouping sea ice cores based on region or ice
type improved the representativeness. With only a small sample size, however, a high
risk of obtaining non-representative estimates remains. Sea ice algal chl a biomass
estimates based on the dominant ice class alone showed a better agreement between
ice core and remotely operated vehicle estimates. Grouping ice core measurements
yielded no improvement in NPP estimates, highlighting the importance of accounting
for the spatial variability of both the chl a biomass and bottom-ice light in order to
get representative estimates. Profile-based measurements of ice algae chl a biomass
identified sea ice ridges as an underappreciated component of the Arctic ecosystem because chl a biomass was significantly greater in this unique habitat. Sea ice ridges
are not easily captured with ice coring methods and thus require more attention in future
studies. Based on our results, we provide recommendations for designing an efficient
and effective sea ice algal sampling program for the summer season.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
,
peerRev
Format:
application/pdf
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