Role of environmental factors on phytoplankton bloom initiation under landfast sea ice in Resolute Passage, Canada.

Mundy, Christopher John; Gosselin, Michel; Gratton, Yves; Brown, Kristina; Galindo, Virginie; Campbell, Kaley; Levasseur, Maurice; Barber, David G.; Papakyriakou, Tim N. et Bélanger, Simon (2014). Role of environmental factors on phytoplankton bloom initiation under landfast sea ice in Resolute Passage, Canada. Marine Ecology Progress Series , vol. 497 . pp. 39-49. DOI: 10.3354/meps10587.

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Résumé

It has been common practice in scientific studies to assume negligible phytoplankton production when the ocean is ice-covered, due to the strong light attenuation properties of snow, sea ice, and ice algae. Recent observations of massive under-ice blooms in the Arctic challenge this concept and call for a re-evaluation of light conditions prevailing under ice during the melt period. Using hydrographic data collected under landfast ice cover in Resolute Passage, Nunavut, Canada between 9 May and 21 June 2010, we documented the exponential growth phase of a substantial under-ice phytoplankton bloom. Numerous factors appeared to influence bloom initiation: (1) transmitted light increased with the onset of snowmelt and termination of the ice algal bloom; (2) initial phytoplankton growth resulted in the accumulation of biomass below the developing surface melt layer where nutrient concentrations were high and turbulent mixing was relatively low; and (3) melt pond formation rapidly increased light transmission, while spring-tidal energy helped form a surface mixed layer influenced by ice melt—both were believed to influence the final rapid increase in phytoplankton growth. By the end of the study, nitrate+nitrite was depleted in the upper 10 m of the water column and the under-ice bloom had accumulated 508 mg chl a m^-2 with a new production estimate of 17.5 g C m^-2 over the upper 50 m of the water column. The timing of bloom initiation with melt onset suggests a strong link to climate change where sea ice is both thinning and melting earlier, the implication being an earlier and more ubiquitous phytoplankton bloom in Arctic ice-covered regions.

Type de document:	Article
Mots-clés libres:	under-ice bloom; phytoplankton; arctic; sea ice melt; transmitted PAR
Centre:	Centre Eau Terre Environnement
Date de dépôt:	11 avr. 2018 13:42
Dernière modification:	25 nov. 2020 14:16
URI:	https://espace.inrs.ca/id/eprint/3641

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