A biomarker-based investigation of the mid-winter ecosystem in Rijpfjorden, Svalbard
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- Brown, T.A., Hegseth, E.N. & Belt, S.T. Polar Biol (2015) 38: 37. doi:10.1007/s00300-013-1352-2
The seasonality of Arctic climate has a pronounced influence on marine ecosystems. The spring bloom is known to be especially important to the structure of Arctic marine ecosystems, yet comparatively little is known about activity during winter. Previously, analysis of diatom-derived highly branched isoprenoid (HBI) lipids has provided useful data on organic carbon inputs to Arctic ecosystems during spring and summer. Here, we aimed to determine whether these lipids and their sources could also be identified during winter and whether HBI distributions in heterotrophs could be linked to seasonal food supply. A selection of heterotrophs was obtained from the water column as part of the Polar Night Cruise in Rijpfjorden during January 2012, and the sea ice-specific biomarker IP25 and other HBIs were identified in the majority of these. IP25 and other HBIs were also detected in some sediments collected at the same time, but were absent from sea ice and seawater samples. However, analysis of algal cultures from each environment provided some information on the likely origin of the HBIs in sediments and heterotrophs. The similarity of the HBI distributions in sediments and some heterotrophs provides some evidence for benthic feeding during winter, although an alternative explanation involving retention of HBIs from previous spring/summer feeding cannot be discounted at this stage. More information on HBI residence times in heterotrophs is required before these two explanations can be distinguished. Nevertheless, the analysis of HBI lipids would appear to have potential in providing novel information regarding Arctic ecosystems during winter.