Arctic mid-winter phytoplankton growth revealed by autonomous profilers

Area of Science:

• Marine Biology
• Oceanography
• Polar Science

Background:

• The prevailing view is that Arctic marine phytoplankton growth requires sea ice melt for sufficient light.
• Observational evidence supporting this paradigm, especially during winter and spring, is limited.

Purpose of the Study:

• To investigate phytoplankton dynamics and ocean optics in the Arctic during and after the polar night.
• To challenge the traditional understanding of Arctic phytoplankton bloom initiation.

Main Methods:

• Utilized autonomous, ice-avoiding profiling floats for continuous data collection over two annual cycles.
• Measured ocean optics and phytoplankton characteristics in Baffin Bay, an ice-covered Arctic sea.

Main Results:

• Demonstrated net phytoplankton growth occurring under 100% ice cover as early as February.
• Confirmed that this growth is, at least partly, a result of photosynthesis.
• Observed phytoplankton adaptation to extreme low-light conditions.

Conclusions:

• Arctic phytoplankton exhibit significant adaptation to low-light environments, enabling growth before the spring bloom.
• Phytoplankton can initiate growth under conditions previously thought prohibitive, impacting Arctic marine ecosystem dynamics.