The Ross Sea Polynya Project: Diatom- and Phaeocystis-dominated phytoplankton assemblages in the Ross Sea, Antarctica, 1994–1996

Garrison, David L.; Gibson, Angela H.; Kunze, Holly; Gowing, Marcia M.; Vickers, Chrystal L.; Mathot, Sylvie; Bayre, Ross C.

doi:10.1029/078ars04

Cited by 17 publications

(5 citation statements)

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“…Surface properties were generally more homogeneous than during the preceding summer cruise, with a west‐to‐east decrease in surface salinity (Figure 6f), leading to greater stratification in the east of our study area. Macronutrients were replete at all stations sampled, with water column N + N concentrations generally in excess of 20 μ M. Phytoplankton assemblages were dominated by colonial Phaeocystis antarctica , which appears to be a typical situation for the Ross Sea polynya during spring [ Long et al , 2011a; Tortell et al , 2011; Arrigo and van Dijken , 2004; Garrison et al , 2004].…”

Section: Resultsmentioning

confidence: 99%

“…Rather, our field observations suggest that when irradiance‐mixing conditions are favorable for net primary production, dFe can be drawn down to growth‐limiting concentrations of ∼0.1 nM over a period of less than a month, barring significant iron inputs to surface waters during that time. This scenario implies that iron availability may exert a first‐order control on primary production rates in the Ross Sea polynya during both spring and summer, when the algal community is typically dominated by colonial Phaeocystis antarctica and by a mixed assemblage of P. antarctica and diatoms, respectively [ DiTullio and Smith , 1996; Smith et al , 2000; Arrigo and van Dijken , 2004; Garrison et al , 2004]. This hypothesis is supported by the results of shipboard iron‐addition experiments, which indicate that phytoplankton growth was limited by iron deficiency during both the summer 2005–2006 and spring 2006 cruises [ Bertrand et al , 2007, 2011; Feng et al , 2010; Rose et al , 2009].…”

Section: Discussionmentioning

confidence: 99%

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Early season depletion of dissolved iron in the Ross Sea polynya: Implications for iron dynamics on the Antarctic continental shelf

et al. 2011

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The Ross Sea polynya is among the most productive regions in the Southern Ocean and may constitute a significant oceanic CO2 sink. Based on results from several field studies, this region has been considered seasonally iron limited, whereby a “winter reserve” of dissolved iron (dFe) is progressively depleted during the growing season to low concentrations (∼0.1 nM) that limit phytoplankton growth in the austral summer (December–February). Here we report new iron data for the Ross Sea polynya during austral summer 2005–2006 (27 December–22 January) and the following austral spring 2006 (16 November–3 December). The summer 2005–2006 data show generally low dFe concentrations in polynya surface waters (0.10 ± 0.05 nM in upper 40 m, n = 175), consistent with previous observations. Surprisingly, our spring 2006 data reveal similar low surface dFe concentrations in the polynya (0.06 ± 0.04 nM in upper 40 m, n = 69), in association with relatively high rates of primary production (∼170–260 mmol C m−2 d−1). These results indicate that the winter reserve dFe may be consumed relatively early in the growing season, such that polynya surface waters can become “iron limited” as early as November; i.e., the seasonal depletion of dFe is not necessarily gradual. Satellite observations reveal significant biomass accumulation in the polynya during summer 2006–2007, implying significant sources of “new” dFe to surface waters during this period. Possible sources of this new dFe include episodic vertical exchange, lateral advection, aerosol input, and reductive dissolution of particulate iron.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Early season depletion of dissolved iron in the Ross Sea polynya: Implications for iron dynamics on the Antarctic continental shelf

et al. 2011

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“…Fragilariopsis spp., Pseudonitzschia spp.) form large blooms, particularly near ice edges during summer (Smith & Nelson 1985;Fonda Umani et al 2002;Garrison et al 2003), and contribute substantially to vertical flux of biogenic material either directly or after incorporation into faecal pellets (Smith & Dunbar 1998;Accornero & Gowing 2003). Centric diatoms (e.g.…”

Section: The Biological Settingmentioning

confidence: 99%

Trophic interactions within the Ross Sea continental shelf ecosystem

Smith

Ainley

Cattaneo‐Vietti

2006

Phil. Trans. R. Soc. B

168

120

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The continental shelf of the Ross Sea is one of the Antarctic's most intensively studied regions. We review the available data on the region's physical characteristics (currents and ice concentrations) and their spatial variations, as well as components of the neritic food web, including lower and middle levels (phytoplankton, zooplankton, krill, fishes), the upper trophic levels (seals, penguins, pelagic birds, whales) and benthic fauna. A hypothetical food web is presented. Biotic interactions, such as the role of Euphausia crystallorophias and Pleuragramma antarcticum as grazers of lower levels and food for higher trophic levels, are suggested as being critical. The neritic food web contrasts dramatically with others in the Antarctic that appear to be structured around the keystone species Euphausia superba. Similarly, we suggest that benthic-pelagic coupling is stronger in the Ross Sea than in most other Antarctic regions. We also highlight many of the unknowns within the food web, and discuss the impacts of a changing Ross Sea habitat on the ecosystem.

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“…antarctica have key roles in shaping the food web, and can impair the absorption and export of carbon to the bottom of the Ross Sea [ 16 – 19 ]. Diatoms usually comprise 90% of the phytoplankton along the western continental shelf and in the Terra Nova Bay polynya, where the stratification of the melting ice of the surface waters results in relatively shallow mixed layers (≤20 m) [ 20 , 21 ]. In contrast, in December, P .…”

Section: Introductionmentioning

confidence: 99%

Phytoplankton blooms during austral summer in the Ross Sea, Antarctica: Driving factors and trophic implications

et al. 2017

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During the austral summer of 2014, an oceanographic cruise was conducted in the Ross Sea in the framework of the RoME (Ross Sea Mesoscale Experiment) Project. Forty-three hydrological stations were sampled within three different areas: the northern Ross Sea (RoME 1), Terra Nova Bay (RoME 2), and the southern Ross Sea (RoME 3). The ecological and photophysiological characteristics of the phytoplankton were investigated (i.e., size structure, functional groups, PSII maximum quantum efficiency, photoprotective pigments), as related to hydrographic and chemical features. The aim was to identify the mechanisms that modulate phytoplankton blooms, and consequently, the fate of organic materials produced by the blooms. The observed biomass standing stocks were very high (e.g., integrated chlorophyll-a up to 371 mg m-2 in the top 100 m). Large differences in phytoplankton community composition, relative contribution of functional groups and photosynthetic parameters were observed among the three subsystems. The diatoms (in different physiological status) were the dominant taxa in RoME 1 and RoME 3; in RoME 1, a post-bloom phase was identified, whereas in RoME 3, an active phytoplankton bloom occurred. In RoME 2, diatoms co-occurred with Phaeocystis antarctica, but were vertically segregated by the upper mixed layer, with senescent diatoms dominating in the upper layer, and P. antarctica blooming in the deeper layer. The dominance of the phytoplankton micro-fraction over the whole area and the high Chl-a suggested the prevalence of non-grazed large cells, independent of the distribution of the two functional groups. These data emphasise the occurrence of significant temporal changes in the phytoplankton biomass in the Ross Sea during austral summer. The mechanisms that drive such changes and the fate of the carbon production are probably related to the variations in the limiting factors induced by the concurrent hydrological modifications to the Ross Sea, and they remain to be fully clarified. The comparison of conditions observed during summer 2014 and those reported for previous years reveal considerably different ecological assets that might be the result of current climate change. This suggests that further changes can be expected in the future, even at larger oceanic scales.

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The Ross Sea Polynya Project: Diatom- and Phaeocystis-dominated phytoplankton assemblages in the Ross Sea, Antarctica, 1994–1996

Cited by 17 publications

References 50 publications

Early season depletion of dissolved iron in the Ross Sea polynya: Implications for iron dynamics on the Antarctic continental shelf

Early season depletion of dissolved iron in the Ross Sea polynya: Implications for iron dynamics on the Antarctic continental shelf

Trophic interactions within the Ross Sea continental shelf ecosystem

Phytoplankton blooms during austral summer in the Ross Sea, Antarctica: Driving factors and trophic implications

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