Always ready? Primary production of Arctic phytoplankton at the end of the polar night

Abstract

The end of the polar night with the concurrent onset of photosynthetic biomass production ultimately leads to the spring bloom, which represents the most important event of primary production for the Arctic marine ecosystem. This dataset shows, for the first time, significant in situ biomass accumulation during the dark–light transition in the high Arctic, as well as the earliest recorded positive net primary production rates together with constant chlorophyll a‐normalized potential for primary production through winter and spring. The results indicate a high physiological capacity to perform photosynthesis upon re‐illumination, which is in the same range as that observed during the spring bloom. Put in context with other data, the results of this study indicate that also active cells originating from the low winter standing stock in the water column, rather than solely resting stages from the sediment, can seed early spring bloom assemblages.

A story of resilience: Arctic diatom Chaetoceros gelidus exhibited high physiological plasticity to changing CO2 and light levels

“…Arctic phytoplankton, particularly diatoms (Lacour et al, 2019) are highly efficient in adjusting to fluctuating light and are capable of keeping their photosynthetic apparatus functional over the dark winter period (Hoppe, 2021). In the present study, the comparable Fv/Fm values under variable light and CO 2 levels s u g g e s t e d t h a t C .…”

“…Croteau et al (2022) observed that the spring bloom succession is controlled by the shift in growth light optima among the bloom-forming Arctic diatom species. However, the experimental studies revealed that Arctic diatoms possess high photophysiological plasticity to adjust to such fluctuating light levels (Lacour et al, 2018;Lacour et al, 2019;Hoppe, 2021). However, other stress factors like increasing CO 2 levels in combination with variable irradiance may affect the carbon capture potential of the bloom-forming diatoms in the Arctic, and such studies on multiple stressors are scarce from this region.…”

Controls on Polar Southern Ocean Deep Chlorophyll Maxima: Viewpoints From Multiple Observational Platforms

“…However, the perturbation experiments by Latour et al. (2023) strongly suggest that these cells remain primed for more optimal conditions (such as nutrient replete and high light, where they could grow faster (Table S1 in Supporting Information S1)), as observed in high‐latitude polar regions of the Arctic (Hoppe, 2021) and Antarctic (Kennedy et al., 2019).…”

“…Thus, diatoms probably exist in the DCM/DBM with sufficient resources for low rates of NPP (Figure 3) in a subsurface niche that enables them to continue to be productive for months. However, the perturbation experiments by Latour et al (2023) strongly suggest that these cells remain primed for more optimal conditions (such as nutrient replete and high light, where they could grow faster (Table S1 in Supporting Information S1)), as observed in high-latitude polar regions of the Arctic (Hoppe, 2021) and Antarctic (Kennedy et al, 2019).…”

Biogeochemical River Runoff Drives Intense Coastal Arctic Ocean CO2 Outgassing

“…In addition, the ED-SBS has four key plankton functional types (PFTs) characteristic of the western AO: diatoms, large eukaryotes, and small and large zooplankton. To represent the observed phytoplankton biomass that is maintained under sea ice in winter, no mortality or grazing occur when phytoplankton biomass is below 0.05 mmolC m −3 (Hoppe, 2022;Randelhoff et al, 2020). ED-SBS also includes terrestrial inputs from the Mackenzie River.…”