An under‑ice bloom of mixotrophic haptophytes in low nutrient and freshwater‑influenced Arctic waters
The pelagic spring bloom is essential for Arctic marine food webs, and a crucial driver of carbon transport to the ocean depths. A critical challenge is understanding its timing and magnitude, to predict its changes in coming decades. Spring bloom onset is typically light-limited, beginning when irr...
| Published in: | Scientific Reports |
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| Main Authors: | , , , , , , , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
2021
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| Subjects: | |
| Online Access: | https://pure.au.dk/portal/en/publications/5199bc99-f85f-4670-a7db-174dc127ad75 https://doi.org/10.1038/s41598-021-82413-y |
| Summary: | The pelagic spring bloom is essential for Arctic marine food webs, and a crucial driver of carbon transport to the ocean depths. A critical challenge is understanding its timing and magnitude, to predict its changes in coming decades. Spring bloom onset is typically light-limited, beginning when irradiance increases or during ice breakup. Here we report an acute 9-day under-ice algal bloom in nutrient-poor, freshwater-influenced water under 1-m thick sea ice. It was dominated by mixotrophic brackish water haptophytes (Chrysochromulina/ Prymnesium) that produced 5.7 g C m −2 new production. This estimate represents about half the annual pelagic production, occurring below sea ice with a large contribution from the mixotrophic algae bloom. The freshwater-influenced, nutrient-dilute and low light environment combined with mixotrophic community dominance implies that phagotrophy played a critical role in the under-ice bloom. We argue that such blooms dominated by potentially toxic mixotrophic algae might become more common and widespread in the future Arctic Ocean. |
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