Seasonal environmental transitions and metabolic plasticity in a sea-ice alga from an individual cell perspective.

Sea-ice microalgae are a key source of energy and nutrient supply to polar marine food webs, particularly during spring, prior to open-water phytoplankton blooms. The nutritional quality of microalgae as a food source depends on their biomolecular (lipid:protein:carbohydrate) composition. In this st...

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Bibliographic Details
Published in:Scientific Reports
Main Authors: Duncan, Rebecca J, Søreide, Janne E, Nielsen, Daniel A, Varpe, Øystein, Wiktor, Józef, Tobin, Mark J, Pitusi, Vanessa, Petrou, Katherina
Format: Article in Journal/Newspaper
Language:English
Published: Nature Publishing Group 2024
Subjects:
Nitzschia frigida
Arctic
Biogeochemical cycling
Microalgae
Sea ice
Svalbard
Climate change
Phytoplankton
Online Access:https://doi.org/10.1038/s41598-024-65273-0
https://pubmed.ncbi.nlm.nih.gov/38951587
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11217269/
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Summary:Sea-ice microalgae are a key source of energy and nutrient supply to polar marine food webs, particularly during spring, prior to open-water phytoplankton blooms. The nutritional quality of microalgae as a food source depends on their biomolecular (lipid:protein:carbohydrate) composition. In this study, we used synchrotron-based Fourier transform infra-red microspectroscopy (s-FTIR) to measure the biomolecular content of a dominant sea-ice taxa, Nitzschia frigida, from natural land-fast ice communities throughout the Arctic spring season. Repeated sampling over six weeks from an inner (relatively stable) and an outer (relatively dynamic) fjord site revealed high intra-specific variability in biomolecular content, elucidating the plasticity of N. frigida to adjust to the dynamic sea ice and water conditions. Environmental triggers indicating the end of productivity in the ice and onset of ice melt, including nitrogen limitation and increased water temperature, drove an increase in lipid and fatty acids stores, and a decline in protein and carbohydrate content. In the context of climate change and the predicted Atlantification of the Arctic, dynamic mixing and abrupt warmer water advection could truncate these important end-of-season environmental shifts, causing the algae to be released from the ice prior to adequate lipid storage, influencing carbon transfer through the polar marine system.

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