Seasonal modulation of phytoplankton biomass in the Southern Ocean

Arteaga, Lionel; Boss, Emmanuel; Behrenfeld, Michael J.; Westberry, T. K.; Sarmiento, Jorge L.

doi:10.1038/s41467-020-19157-2

Cited by 81 publications

(84 citation statements)

References 53 publications

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“…A recent study concentrating on Maud Rise also concludes that sea ice retreat controls the bloom climax timing (von Berg et al, 2020). Whereas other studies using BGC Argo floats show that bloom onset (Arteaga et al, 2020) or growth initiation (approximately corresponding to the bloom onset described here, thus preceding bloom initiation and climax; Hague and Vichi, 2021) can occur well before sea ice retreat (possibly due to unconsolidated ice relieving light limitation; Hague and Vichi, 2021).…”

Section: Environmental Control: Sea Ice Concentrationmentioning

confidence: 47%

“…As blooms happen rather late in the season in our study area because of the sea ice cover and compared to the rest of the Southern Ocean (Ardyna et al, 2017), we can characterize our study area as having summer blooms rather than spring blooms. Indeed, a study based on BGC Argo floats concerning the Southern Ocean (but with very limited float coverage in our study area) suggests that the extremely low light levels under the sea ice prevented the early winter onset of the blooms in the seasonal ice zone, as opposed to the other zones (Arteaga et al, 2020).…”

Section: Environmental Control: Mixed Layer Depthmentioning

confidence: 84%

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Phenology and Environmental Control of Phytoplankton Blooms in the Kong Håkon VII Hav in the Southern Ocean

et al. 2021

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Knowing the magnitude and timing of pelagic primary production is important for ecosystem and carbon sequestration studies, in addition to providing basic understanding of phytoplankton functioning. In this study we use data from an ecosystem cruise to Kong Håkon VII Hav, in the Atlantic sector of the Southern Ocean, in March 2019 and more than two decades of satellite-derived ocean color to study phytoplankton bloom phenology. During the cruise we observed phytoplankton blooms in different bloom phases. By correlating bloom phenology indices (i.e., bloom initiation and end) based on satellite remote sensing to the timing of changes in environmental conditions (i.e., sea ice, light, and mixed layer depth) we studied the environmental factors that seemingly drive phytoplankton blooms in the area. Our results show that blooms mainly take place in January and February, consistent with previous studies that include the area. Sea ice retreat controls the bloom initiation in particular along the coast and the western part of the study area, whereas bloom end is not primarily connected to sea ice advance. Light availability in general is not appearing to control the bloom termination, neither is nutrient availability based on the autumn cruise where we observed non-depleted macronutrient reservoirs in the surface. Instead, we surmise that zooplankton grazing plays a potentially large role to end the bloom, and thus controls its duration. The spatial correlation of the highest bloom magnitude with marked topographic features indicate that the interaction of ocean currents with sea floor topography enhances primary productivity in this area, probably by natural fertilization. Based on the bloom timing and magnitude patterns, we identified five different bloom regimes in the area. A more detailed understanding of the region will help to highlight areas with the highest relevance for the carbon cycle, the marine ecosystem and spatial management. With this gained understanding of bloom phenology, it will also be possible to study potential shifts in bloom timing and associated trophic mismatch caused by environmental changes.

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Section: Environmental Control: Sea Ice Concentrationmentioning

confidence: 47%

Section: Environmental Control: Mixed Layer Depthmentioning

confidence: 84%

Phenology and Environmental Control of Phytoplankton Blooms in the Kong Håkon VII Hav in the Southern Ocean

et al. 2021

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“…Although not a focus of the present study, we note that tracking and anticipating changes to primary production in the Southern Ocean should include that within sea ice (Arrigo, 2014;Saenz and Arrigo, 2014;van Leeuwe et al, 2018) and beneath it (Arteaga et al, 2020). Although sea ice algae only contribute ∼1% of total Southern Ocean primary production, and 12-50% of total primary production in the sea ice zone (Kottmeier et al, 1987;Grossi et al, 1987;Saenz and Arrigo, 2014;van Leeuwe et al, 2018), sea ice algae are of disproportionate ecological importance because their production occurs in locations and at times when production in the water column is low (Quetin et al, 1996;Saenz and Arrigo, 2014;McCormack et al, in review).…”

Section: Primary Production By Sea Ice Algaementioning

confidence: 99%

Evidence for the Impact of Climate Change on Primary Producers in the Southern Ocean

et al. 2021

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Within the framework of the Marine Ecosystem Assessment for the Southern Ocean (MEASO), this paper brings together analyses of recent trends in phytoplankton biomass, primary production and irradiance at the base of the mixed layer in the Southern Ocean and summarises future projections. Satellite observations suggest that phytoplankton biomass in the mixed-layer has increased over the last 20 years in most (but not all) parts of the Southern Ocean, whereas primary production at the base of the mixed-layer has likely decreased over the same period. Different satellite models of primary production (Vertically Generalised versus Carbon Based Production Models) give different patterns and directions of recent change in net primary production (NPP). At present, the satellite record is not long enough to distinguish between trends and climate-related cycles in primary production. Over the next 100 years, Earth system models project increasing NPP in the water column in the MEASO northern and Antarctic zones but decreases in the Subantarctic zone. Low confidence in these projections arises from: (1) the difficulty in mapping supply mechanisms for key nutrients (silicate, iron); and (2) understanding the effects of multiple stressors (including irradiance, nutrients, temperature, pCO2, pH, grazing) on different species of Antarctic phytoplankton. Notwithstanding these uncertainties, there are likely to be changes to the seasonal patterns of production and the microbial community present over the next 50–100 years and these changes will have ecological consequences across Southern Ocean food-webs, especially on key species such as Antarctic krill and silverfish.

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“…Biogeochemical processes in the interior of EB are apparently of minor importance for the oxygen dynamics within EB. issue Behrenfeld, 2010;Arteaga et al, 2020;Smetacek, 1985). The biomass eventually sinks to depth where it degrades and issues oxygen consumption.…”

Section: Residence and Ventilation Timesmentioning

confidence: 99%

Retracing Hypoxia in Eckernförde Bight (Baltic Sea)

Dietze¹,

Löptien²

2021

Preprint

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Abstract. In recent years, upwelling events of low-oxygenated deep water have been repeatedly observed in Eckernförde Bight (EB) situated in the Baltic Sea, Germany. Many of these events were related to massive fish-kill incidents – with negative consequences for commercial fisheries and tourism. The aim of this study is to dissect underlying mechanisms and to explore the potential of existing monitoring programs to predict these events. Our main tool is an ultra-high spatially resolved general ocean circulation model which drives an elementary representation of the biogeochemical dynamics of dissolved oxygen (dubbed MOMBE and EckO2, respectively). In addition, we integrate artificial clocks that measure the residence time of the water in EB along with timescales of (surface) ventilation. We present an ensemble of hind cast model simulations, covering the period from 2000 up to 2018, designed to cover a range of poorly known model parameters for vertical background mixing (diffusivity) and local oxygen consumption within EB. Our results indicate that the dynamics of low (hypoxic) oxygen concentrations in bottom waters deep inside EB is, to first order, determined by the following antagonistic processes: (1) the inflow of low-oxygenated water from the Kiel Bight (KB) – especially from July to October and (2) the local ventilation of bottom waters by local (within EB) subduction and vertical mixing. Biogeochemical processes that consume oxygen locally, are apparently of minor importance for the development of hypoxic events. Reverse reasoning suggests that subduction and mixing processes in EB contribute, under certain environmental conditions, to the ventilation of the KB by exporting recently-ventilated waters enriched in oxygen. A detailed analysis of the 2017 fish-kill incident highlights the interplay between westerly winds importing hypoxia from KB and ventilating easterly winds which subduct oxygenated water. Finally, we explore the capabilities of – comparably computationally cheap – feed-forward artificial neuronal networks to forecast hypoxia deep in EB based on data at a monitoring site at the entrance of EB.

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Seasonal modulation of phytoplankton biomass in the Southern Ocean

Cited by 81 publications

References 53 publications

Phenology and Environmental Control of Phytoplankton Blooms in the Kong Håkon VII Hav in the Southern Ocean

Phenology and Environmental Control of Phytoplankton Blooms in the Kong Håkon VII Hav in the Southern Ocean

Evidence for the Impact of Climate Change on Primary Producers in the Southern Ocean

Retracing Hypoxia in Eckernförde Bight (Baltic Sea)

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