Factors controlling the distribution of diatoms and Phaeocystis in the Ross Sea

Goffart, Anne; Catalano, Guilio; Hecq, Jean-Henri

doi:10.1016/s0924-7963(00)00065-8

Cited by 89 publications

(69 citation statements)

References 40 publications

(43 reference statements)

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“…On this basis, it has been argued that the ability of P. antarctica to maintain high rates of photosynthesis at low or variable irradiance allows this species to dominate the poorly stratified waters of the southern Ross Sea during spring (Leventer & Dunbar 1996, Arrigo et al 1998b, 1999, Goffart et al 2000. This hypothesis can explain the observed spatial and temporal separation of P. antarctica and diatom blooms in the Ross Sea, if it is assumed that diatoms are better adapted to the stable higher irradiance of more stratified waters (Arrigo et al 1998b, 1999, 2003, Sedwick et al 2000.…”

Section: Abstract: Phaeocystis Antarctica · Growth · Iron · Light · mentioning

confidence: 99%

“…Here the phytoplankton community is typically dominated by blooms of colonial Phaeocystis antarctica in austral spring and early summer (October to December), followed by diatom blooms in mid-to late summer (Bunt & Wood 1963, El-Sayed et al 1983, Comiso et al 1993, DiTullio & Smith 1996, Smith & Gordon 1997, Arrigo et al 1998b, Goffart et al 2000, Arrigo & van Dijken 2004. P. antarctica is considered a keystone species in this region, because of its major role in the biogeochemical cycling of carbon, sulfur and nutrient elements (Gibson et al 1990, Smith et al 1991 , above which growth rates decreased to 0.27 d -1 at an irradiance of 314 µE m -2 s -1…”

Section: Introductionmentioning

confidence: 99%

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Influence of irradiance and iron on the growth of colonial Phaeocystis antarctica: implications for seasonal bloom dynamics in the Ross Sea, Antarctica

Garcia¹,

Sedwick²,

DiTullio³

2009

Aquat. Microb. Ecol.

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Laboratory culture experiments were used to investigate the growth rate of colonial Phaeocystis antarctica as a function of irradiance and dissolved iron concentration. The experiments were conducted with a P. antarctica strain isolated from the southern Ross Sea, Antarctica, and made use of natural, low-iron (< 0.2 nM dissolved Fe) filtered seawater as a growth medium, thereby avoiding the addition of synthetic organic ligands to regulate dissolved iron concentrations. Under ironand nutrient-replete conditions, colonial P. antarctica attained an average maximum cell-specific growth rate of 0.37 d -1 at an irradiance of 68 µE m -2 s -1, above which growth rates decreased to 0.27 d -1 at an irradiance of 314 µE m -2 s -1. The dependence of growth rate on ambient dissolved iron concentration was examined in dose-response type bioassay experiments using realistic subnanomolar additions of dissolved iron. The experimental results indicate significant changes in the iron requirements for growth of colonial P. antarctica as a function of irradiance, with our estimates of the half-saturation constant for growth with respect to dissolved iron (K μ ) ranging from 0.26 nM at 20 µE m -2 s -1 , to 0.045 nM at ~40 µE m -2 s -1 and to 0.19 nM at ~90 µE m -2 s -1. We interpret these variations in K μ as reflecting an increase in the cellular iron requirements of colonial P. antarctica at suboptimal and supraoptimal irradiance, such that the cells require higher ambient dissolved iron concentrations to attain maximum growth rates under such irradiance conditions. The experiments also provide evidence of a relationship between iron availability and the relative proportion of colonial versus solitary P. antarctica cells, whereby the colonial form appears to be favored by higher dissolved iron concentrations. Our experimental results suggest that the initiation and termination of colonial P. antarctica blooms in the Ross Sea are determined by the combined effects of irradiancedriven changes in cellular iron requirements and a seasonal decrease in dissolved iron availability. KEY WORDS: Phaeocystis antarctica · Growth · Iron · Light · Ross Sea · Bloom dynamicsResale or republication not permitted without written consent of the publisher Aquat Microb Ecol 57: 203-220, 2009 DiTullio & Smith 1995, Arrigo et al. 1999, Sweeney et al. 2000, Schoemann et al. 2005. The factors that control the spatial and temporal distribution of P. antarctica blooms in the southern Ross Sea are not well understood. Bottom-up controls by irradiance, iron and vitamin B 12 have been suggested (Arrigo et al. 1998b, Fitzwater et al. 2000, Sedwick et al. 2000, Smith et al. 2003a, Bertrand et al. 2007), whereas top-down control by grazing pressure is not thought to be significant (Caron et al. 2000, Tagliabue & Arrigo 2003. Field observations document a general decrease in the depth of the surface mixed layer, which allows an increase in mean irradiance during the growing season (Arrigo et al. 1998b, Smith et al. 2003a, Sweeney 2003. Over the same p...

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Section: Abstract: Phaeocystis Antarctica · Growth · Iron · Light · mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Influence of irradiance and iron on the growth of colonial Phaeocystis antarctica: implications for seasonal bloom dynamics in the Ross Sea, Antarctica

Garcia¹,

Sedwick²,

DiTullio³

2009

Aquat. Microb. Ecol.

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“…This study reveals remarkable differences in Phaeocystis and diatom dominance during the earliest stage of the growth season in the Ross Sea, whereby the governing physical conditions are largely determining the Ž . phytoplankton distribution Goffart et al, 2000 . The corresponding nitrogen utilisation evidences some small differences between Phaeocystis and diatom predominance, the overall trend being highly characteristic for the onset of the phytoplankton develop-Ž ment after ice melting though Cota et al, 1992; .…”

Section: Resultsmentioning

confidence: 99%

“…The HF stock is assumed to be indicative of the presence of Phaeocystis. This assumption is based on the reported predominance of Phaeocystis and minor contribution of other prymnesiophytes in the Ross Sea ŽPalmisano et al, 1986;DiTullio and Smith, 1995;. Goffart et al, 2000 . Samples for productivity incubations were obtained from depths corresponding to 100%, 50%, .…”

Section: Methodsmentioning

confidence: 99%

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Nutrient depletions in the Ross Sea and their relation with pigment stocks

Goeyens

Elskens

Catalano³

et al. 2000

Journal of Marine Systems

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The present article depicts a first attempt to relate the governing nutrient uptake regime and phytopigment signature of the Ross Sea. Based on nutrient and phytopigment data obtained during two cruises in the Ross Sea, two distinct groups Ž . were recognised. The first one was characterised by moderate nutrient nitrate and silicic acid depletions in combination with relatively high diatom and Phaeocystis abundance. The second group showed very low nutrient depletions and very poor diatom abundance. Average depth specific nitrate depletions were 8.1 and 1.1 mM and average silicic acid depletions were 21.5 and 1.3 mM, respectively. The nutrient consumption patterns did not match the conditions of silicic acid excess Ž . Ž . SEA or nitrate excess areas NEA , a clear trend being probably obscured by very poor seasonal maturity of several sampling stations.The contrast between both groups is largely explained by small differences in nitrogen uptake regime of the major phytoplankters. During early season, the diatoms meet the majority of their nitrogen requirements by nitrate uptake, with few exceptions where ammonium is the most important nitrogenous substrate. On average, their nitrate uptake capacity is lower Ž y1 than that of Phaeocystis average specific nitrate uptake rates were 0.021 and 0.036 day for diatoms and Phaeocystis, . respectively . The latter phytoplankton always shows predominance of nitrate uptake. Both groups are subject to inhibition of nitrate uptake when ammonium availability increases, and it is likely that the diatoms are more sensitive to the inhibitory effect of ammonium. q

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Net community production and carbon export during the late summer in the Ross Sea, Antarctica

DeJong

Dunbar

Koweek

et al. 2017

Global Biogeochemical Cycles

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The phytoplankton bloom in the Ross Sea is the largest in spatial extent and one of the most productive in Antarctica, yet the fate of the summer bloom remains poorly understood. Here we present carbon system data from the first biogeochemical process cruise to be conducted in both the western and central Ross Sea during late summer (February–March 2013). Using one‐dimensional carbon budgets, we found evidence for substantial positive net community production (425 ± 204 mmol C m−2 d−1) during the late summer in Terra Nova Bay (TNB) of the western Ross Sea, which was rapidly exported to below 200 m. In addition, seasonally integrated carbon export was higher in diatom‐dominated TNB (7.3 ± 0.9 mol C m−2) compared to the Phaeocystis antarctica‐dominated central Ross Sea (3.4 ± 0.8 mol C m−2). Substantial late summer productivity and export may be a widespread phenomenon in Antarctic coastal regions that is not accounted for in regional carbon models.

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Factors controlling the distribution of diatoms and Phaeocystis in the Ross Sea

Cited by 89 publications

References 40 publications

Influence of irradiance and iron on the growth of colonial Phaeocystis antarctica: implications for seasonal bloom dynamics in the Ross Sea, Antarctica

Influence of irradiance and iron on the growth of colonial Phaeocystis antarctica: implications for seasonal bloom dynamics in the Ross Sea, Antarctica

Nutrient depletions in the Ross Sea and their relation with pigment stocks

Net community production and carbon export during the late summer in the Ross Sea, Antarctica

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