Transfer of ice algae-based energy in a summerly Arctic Ocean: Food web insights revealed by state-of-the-art biomarker approaches

• Main Authors: Kohlbach, Doreen, Graeve, Martin, David, Carmen, Lange, Benjamin, Flores, Hauke
• Format: Conference Object
• Language: unknown
• Published: 2015
• Subjects: Arctic; Arctic Ocean; Calanus glacialis; Calanus hyperboreus; Climate change; ice algae; Phytoplankton; Sea ice; Zooplankton; Copepods
• Online Access: https://epic.awi.de/id/eprint/37562/; https://hdl.handle.net/10013/epic.50439

Polar ecosystems thrive significantly on carbon synthesized by sea ice-associated microalgae. The underside of sea ice in polar regions represents a natural habitat for heterotrophic organisms, e. g. copepods and amphipods. The under-ice fauna plays a key role in transferring ice algae-produced carbon into pelagic and benthic food webs of polar ecosystems. The under-ice community and the associated pelagic food webs are largely affected by climate change accompanied by the reduction of sea ice coverage and increase in the duration of the melt season. Until now, the degree to which Arctic marine food webs depend on sea ice-derived carbon is still unclear. In order to improve our understanding of the potential ecological consequences of a changing sea ice environment, we aimed to quantify the transfer of ice algae-produced carbon into the under-ice community and from there into pelagic food webs. Sample collection was carried out during the RV Polarstern expedition of ARK XXVII-3 (August-September 2012) throughout the Eastern Central Arctic Ocean north of 80°N. The carbon sources of abundant under-ice zooplankton species were studied using stable isotope analysis (SIA) of natural abundance carbon and nitrogen, and lipid fingerprinting.Compound-specific SIA (CSIA) of fatty acid trophic markers (FATM) was used to separate the trophic signal of phytoplankton FATM from those of ice algae. Mixing models were used to determine the relative contribution of FATM of the two carbon sources. We found the Arctic copepods Calanus glacialis and Calanus hyperboreus feeding on both, ice algae and pelagic phytoplankton. Several amphipod species demonstrated a high dietary dependency on ice algae.