An under‑ice bloom of mixotrophic haptophytes in low nutrient and freshwater‑influenced Arctic waters

Research output: Contribution to journalJournal articleResearchpeer-review

  • Dorte H. Søgaard
  • Brian K. Sorrell
  • Mikael K. Sejr
  • Per Andersen
  • Søren Rysgaard
  • Hansen, Per Juel
  • Annaliina Skyttä
  • Signe Lemcke
  • Lars Chresten Lund-Hansen
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.
Original languageEnglish
Article number11:2915
JournalScientific Reports
Number of pages8
Publication statusPublished - 2021

ID: 256327624