Phytoplankton dynamics in a changing Arctic Ocean

Ardyna, Mathieu; Arrigo, Kevin R.

doi:10.1038/s41558-020-0905-y

Cited by 203 publications

(204 citation statements)

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“…As the sea ice cover in the Arctic Ocean is shrinking and thinning, blooms of phytoplankton are now beginning earlier and already partly below the consolidated ice cover (Kahru et al, 2011;Ardyna and Arrigo, 2020). Through a series of conceptual models, Wassmann and Reigstad (2011) suggested that the earlier onset of blooms would be reflected in the export of carbon, with the largest changes occurring in the northern portions of the SIZ.…”

Section: Earlier Phytoplankton Blooms Trigger Earlier Vertical Export Pulsesmentioning

confidence: 99%

“…Thus, the whole Arctic Ocean may eventually transition into a seasonally ice-covered ocean. As a result of the shorter, more transparent, and dynamic sea ice cover, large under-ice phytoplankton blooms in the Arctic have been reported (Fortier et al, 2002;Arrigo et al, 2012;Mundy et al, 2014;Assmy et al, 2017;Johnsen et al, 2018;Ardyna and Arrigo, 2020;. Recent studies have described the phytoplankton dynamics and environmental drivers of these under-ice blooms , but the fate of the carbon produced by these blooms is yet to be explored (Ardyna and Arrigo, 2020).…”

Section: Introductionmentioning

confidence: 99%

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Carbon Export in the Seasonal Sea Ice Zone North of Svalbard From Winter to Late Summer

et al. 2021

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Phytoplankton blooms in the Arctic Ocean's seasonal sea ice zone are expected to start earlier and occur further north with retreating and thinning sea ice cover. The current study is the first compilation of phytoplankton bloom development and fate in the seasonally variable sea ice zone north of Svalbard from winter to late summer, using short-term sediment trap deployments. Clear seasonal patterns were discovered, with low winter and pre-bloom phytoplankton standing stocks and export fluxes, a short and intense productive season in May and June, and low Chl a standing stocks but moderate carbon export fluxes in the autumn post-bloom conditions. We observed intense phytoplankton blooms with Chl a standing stocks of >350 mg m−2 below consolidated sea ice cover, dominated by the prymnesiophyte Phaeocystis pouchetii. The largest vertical organic carbon export fluxes to 100 m, of up to 513 mg C m−2 day−1, were recorded at stations dominated by diatoms, while those dominated by P. pouchetii recorded carbon export fluxes up to 310 mg C m−2 day−1. Fecal pellets from krill and copepods contributed a substantial fraction to carbon export in certain areas, especially where blooms of P. pouchetii dominated and Atlantic water advection was prominent. The interplay between the taxonomic composition of protist assemblages, large grazers, distance to open water, and Atlantic water advection was found to be crucial in determining the fate of the blooms and the magnitude of organic carbon exported out of the surface water column. Previously, the marginal ice zone was considered the most productive region in the area, but our study reveals intense blooms and high export events in ice-covered waters. This is the first comprehensive study on carbon export fluxes for under-ice phytoplankton blooms, a phenomenon suggested to have increased in importance under the new Arctic sea ice regime.

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Section: Earlier Phytoplankton Blooms Trigger Earlier Vertical Export Pulsesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Carbon Export in the Seasonal Sea Ice Zone North of Svalbard From Winter to Late Summer

et al. 2021

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“…The scarcity of nitrogen (N) and phosphorus (P) limits primary production across aquatic ecosystems (Moore et al , 2013; Ardyna & Arrigo, 2020) by regulating the growth and structure of phytoplankton communities (Arrigo, 2005; Follows et al , 2007; Harke et al , 2016). These communities consist of an extremely diverse group of phylogenetically and physiologically distinct phytoplankton (Keeling et al , 2014; Caron et al , 2017).…”

Section: Introductionmentioning

confidence: 99%

Harmful Algal Bloom-Forming Organism Responds to Nutrient Stress Distinctly From Model Phytoplankton

McLean

et al. 2021

Preprint

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Resources such as nitrogen (N) and phosphorus (P) play an important role in primary production and constraining phytoplankton bloom dynamics. Models to predict bloom dynamics require mechanistic knowledge of algal metabolic shifts in response to resource limitation. For well-studied model phytoplankton like diatoms, this information is plentiful. However, for less-studied groups such as the raphidophytes, there remain significant gaps in understanding metabolic changes associated with nutrient limitation. Using a novel combination of metabolomics and transcriptomics, we examined how the harmful algal bloom-forming raphidophyte Heterosigma akashiwo shifts its metabolism under N- and P-stress. We chose H. akashiwo because of its ubiquity within estuarine environments worldwide, where bloom dynamics are influenced by N and P availability. Our results show that each stress phenotype is distinct in both the allocation of carbon and the recycling of macromolecules. Further, we identified biomarkers of N- and P-stress that may be applied in situ to help modelers and stakeholders manage, predict, and prevent future blooms. These findings provide a mechanistic foundation to model the metabolic traits and trade-offs associated with N- and P-stress in H. akashiwo, and evaluate the extent to which these metabolic responses can be inferred in other phytoplankton groups.

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“…They also found that increased chlorophyll-a (Chl-a) was responsible for the sustained increase in annual NPP between 2009 and 2018, particularly along the interior shelf break. These results suggest that additional nutrients were supplied from increased vertical mixing near the shelf break into the nutrient-depleted upper euphotic zone (Arrigo & van Dijken, 2015;Lewis et al, 2020) and that the changes in ocean circulation in response to recent sea ice loss and increased wind mixing could significantly influence biological production (Ardyna & Arrigo, 2020).The Arctic Ocean is experiencing radical modifications in its hydrographic properties and in its overall circulation (Ardyna & Arrigo, 2020). For example, Polyakov et al (2017) reported that the recent increase in Abstract Atlantic-origin cold saline water has previously not been considered an important contributor to the nutrient supply in the Pacific Arctic due to the effective insulation by the overlying Pacific-origin waters that separate the surface mixed layer from the deeper Atlantic Water.…”

mentioning

confidence: 99%

Atlantic‐Origin Cold Saline Water Intrusion and Shoaling of the Nutricline in the Pacific Arctic

Jung

Cho

Park

et al. 2021

Geophysical Research Letters

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The warming (solar insolation) and freshening (sea ice melting and riverine water inputs) of the Arctic Ocean during summer increase stratification and suppress the upward mixing of nutrients into the euphotic zone (Codispoti et al., 2013). However, sea ice is now thinner and less compact (Kwok, 2018; Perovich et al., 2020); thus, the Arctic Ocean is more responsive to wind stress (Kwok et al., 2013), which enhances the nutrient supply (Bluhm et al., 2015). Shelf-break upwelling is becoming more prominent in the Arctic as the sea ice edge retreats poleward with ongoing climate change, exposing the shelf break to more direct wind forcing (Arrigo et al., 2014; Carmack & Chapman, 2003; Tremblay et al., 2011). Recently, Lewis et al. (2020) reported that annual net primary production (NPP) increased by 57% over the Arctic Ocean between 1998 and 2018. They also found that increased chlorophyll-a (Chl-a) was responsible for the sustained increase in annual NPP between 2009 and 2018, particularly along the interior shelf break. These results suggest that additional nutrients were supplied from increased vertical mixing near the shelf break into the nutrient-depleted upper euphotic zone (Arrigo & van Dijken, 2015; Lewis et al., 2020) and that the changes in ocean circulation in response to recent sea ice loss and increased wind mixing could significantly influence biological production (Ardyna & Arrigo, 2020). The Arctic Ocean is experiencing radical modifications in its hydrographic properties and in its overall circulation (Ardyna & Arrigo, 2020). For example, Polyakov et al. (2017) reported that the recent increase in Abstract Atlantic-origin cold saline water has previously not been considered an important contributor to the nutrient supply in the Pacific Arctic due to the effective insulation by the overlying Pacific-origin waters that separate the surface mixed layer from the deeper Atlantic Water. Based on hydrographic observations in the northwestern Chukchi Sea from 2015 to 2017, we demonstrate that the intrusion of Atlantic-origin cold saline water into the halocline boundary between Pacific and Atlanticorigin waters in 2017 lifted Pacific-origin nutrients up to the surface layer. We find that the cyclonic atmospheric circulation in 2017 was considerably strengthened, leading to lateral intrusions of two bodies of cold halocline water from the Eurasian marginal seas into the northwestern Chukchi Sea. Our results reveal that the intrusions of cold halocline waters caused unprecedented shoaling of the nutricline and anomalously high surface phytoplankton blooms in typically highly oligotrophic surface waters in the region during summer. Plain Language Summary Nutrient depletion, especially nitrogen, in Arctic surface waters during the summer is common due to biological uptake and intense stratification caused by sea ice melting and riverine water inputs, which restricts the upward mixing of nutrients into the euphotic zone. Although Atlantic-origin cold saline water has previously not been considered an important ...

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Phytoplankton dynamics in a changing Arctic Ocean

Cited by 203 publications

References 195 publications

Carbon Export in the Seasonal Sea Ice Zone North of Svalbard From Winter to Late Summer

Carbon Export in the Seasonal Sea Ice Zone North of Svalbard From Winter to Late Summer

Harmful Algal Bloom-Forming Organism Responds to Nutrient Stress Distinctly From Model Phytoplankton

Atlantic‐Origin Cold Saline Water Intrusion and Shoaling of the Nutricline in the Pacific Arctic

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