Resource limitation of phytoplankton growth in the Crozet Basin, Subantarctic Southern Ocean

Sedwick, Peter N.; Blain, Stéphane; Quéguiner, Bernard; Griffiths, F. Brian; Fiala, Michel; Bucciarelli, Eva; Denis, Michel

doi:10.1016/s0967-0645(02)00086-3

Cited by 67 publications

(32 citation statements)

References 63 publications

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“…Since similar trends were also found for bioavailable nutrients (Figure 2f-i), it is inferred that the spatial differences in levels of phytoplankton, and especially Cyanobacteria, were mainly governed by the levels of nutrients, as also reported by many other studies [31,38]. …”

Section: Phytoplankton Abundancesupporting

confidence: 87%

Spatial and Temporal Variations in Environmental Variables in Relation to Phytoplankton Community Structure in a Eutrophic River-Type Reservoir

Zhao

Jiao

et al. 2017

Water

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This study assesses spatial and temporal variation in environmental variables in relation to phytoplankton community size and composition in a typically eutrophic river reservoir (Hai River, northern China). The aim is to identify environmental parameters governing spatial and temporal differences in phytoplankton density and composition. Physicochemical parameters, including nutrient concentrations, were determined in monthly surface water samples from 2015. The average concentration of key eutrophication indexes (i.e., total phosphorous (TP: 0.24 ± 0.11 mg·L −1 ), total nitrogen (TN: 2.96 ± 1.60 mg·L −1 ), and Chlorophyll a (Chl a: 38.5 ± 11.5 mg·m −3 )) substantially exceeded threshold values for eutrophic streams. Moreover, the eutrophication increased significantly downstream along the river reservoir as a consequence of an increasing fraction of agricultural and industrial land-use in the watershed. 103 phytoplankton species were identified, of which Chlorophyta was the dominated phylum (47 species), followed by Bacillariophyta (23 species) and Cyanophyta (18 species). No spatial difference in species distribution (ANOVA, p > 0.05) were found, while the temporal differences in species composition exhibited significant heterogeneity (ANOVA, p < 0.001). Phytoplankton abundance was highest in early summer (June and July), with maximum values increasing from 1.78 × 10 8 and 2.80 × 10 8 cells·L −1 in upstream and middle reaches, respectively, to 4.18 × 10 8 cells·L −1 furthest downstream. Cyanophyta, also known as Cyanobacteria and commonly referred to as blue-green algal, are known to constitute algae bloom in eutrophic systems. Common species are Microcystis marginata, Microcystis flos-aquae, and Oscillatoria sp. This was the dominant phyla during summer months, especially in the middle and lower reaches of the stream reservoir where it accounted for 88.9% of the phytoplankton community. Shannon weaver index (H') and Pielous's evenness index (J') were extremely low (1.91-2.43 for H' and 0.39-0.45 for J') in samples collected from the lower part of the stream during the period of algal bloom, indicating an imbalance in the phytoplankton communities. Canonical correspondence analysis (CCA) indicated that water temperature (WT) and possible pH, along with nitrate (NO 3 -N) and nitrite (NO 2 -N), were the most important explanatory parameters in regard to phytoplankton composition. This research provides an understanding of the role of physicochemical water quality parameters in governing algal blooms and phytoplankton composition in river reservoirs.

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Section: Phytoplankton Abundancesupporting

confidence: 87%

Spatial and Temporal Variations in Environmental Variables in Relation to Phytoplankton Community Structure in a Eutrophic River-Type Reservoir

Zhao

Jiao

et al. 2017

Water

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“…Other less well-defined sources of iron may be through upwelling or lateral advection (de Baar et al, 1999;Hiscock et al, 2003;Martin et al, 1990;Bowie et al, 2009). The stimulation of phytoplankton production with iron additions has previously been demonstrated in the SAZ and PFZ zones during both spring and summer (Gervais et al, 2002;Sedwick et al, 2002). Low iron combined with low silicate availability in the SAZ has been shown to favour the growth of non-silicious, iron-efficient phytoplankton species such as eukaryotic picoplankton and cyanobacteria (Hutchins et al, 2001).…”

Section: Introductionmentioning

confidence: 92%

“…Nitrate concentrations are generally higher than silicate, with non-limitation previously demonstrated during summer (Sedwick et al, 2002). Possible reasons for high silicate depletion relative to nitrate include less efficient remineralisation (Cardinal et al, 2005a), or high silicate:nitrate uptake by phytoplankton due to iron limitation (Franck et al, 2000;Watson et al, 2000;Hutchins et al, 2001).…”

Section: Introductionmentioning

confidence: 98%

“…Sequestration of carbon from the atmosphere depends primarily on initial fixation rates during photosynthesis Sedwick et al, 2002;Westwood et al, 2010), with subsequent carbon transfer to the deep ocean dependent on biological recycling, remineralisation rates (Cardinal et al, 2005b), and the sinking/export rates of organic matter (Cardinal et al, 2001;Trull et al, 2001a;Richardson and Jackson, 2007). Optimal gross primary production generally occurs during spring and early summer, following the replenishment of nutrients to surface waters over winter, and coinciding with high light availability and the onset of stratification (Bradford-Grieve et al, 1997;Boyd et al, 1999;Lourey and Trull, 2001;Hiscock et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

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Primary production in the Sub-Antarctic and Polar Frontal Zones south of Tasmania, Australia; SAZ-Sense survey, 2007

Westwood

Griffiths

Webb

et al. 2011

Deep Sea Research Part II: Topical Studies in Oceanography

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The Sub-Antarctic Zone (SAZ) in the Southern Ocean provides a significant sink for atmospheric CO 2 and quantification of this sink is therefore important in models of climate change. During the SAZ-Sense (Sub-Antarctic Sensitivity to Environmental Change) survey conducted during austral summer 2007, we examined CO 2 sequestration through measurement of gross primary production rates using 14 C. Sampling was conducted in the SAZ to the south-west and south-east of Tasmania, and in the Polar Frontal Zone (PFZ) directly south of Tasmania. Despite higher chlorophyll biomass off the south-east of Tasmania, production measurements were similar to the south-west with rates

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“…Si(OH) 4 , nitrate and phosphate concentrations increased with latitude and with depth from the STZ to the PFZ in the present study. Nitrate and phosphate were expected to be nonlimiting (Sedwick et al 2002, Bowie et al 2009). Although the Si(OH) 4 concentration (<1 μmol l -1 ) was near or below the half-saturation constants for Siuptake (from 0.7 to 10 μmol l ) was independent of the Si(OH) 4 concentration (Fig.…”

Section: Production Ratesmentioning

confidence: 99%

Efficient silicon recycling in summer in both the Polar Frontal and Subantarctic Zones of the Southern Ocean

Fripiat¹,

Leblanc²,

Elskens³

et al. 2011

Mar. Ecol. Prog. Ser.

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We measured biogenic silica (bSiO 2 ) dissolution and production rates at 3 Southern Ocean sites with contrasting biogeochemical regimes (SAZ-Sense cruise, January to February 2007). Two sites were located in the Subantarctic Zone (SAZ) southeast and southwest of Tasmania, and 1 site was in the Polar Frontal Zone (PFZ). The measurements were repeated 3 times within a time frame of 4 to 7 d. In the PFZ and the western SAZ, the release of silicon from dissolving bSiO 2 , following a productive period, appeared sufficient to entirely sustain Si demand in surface waters. Biogenic silica dissolution was more efficient in the SAZ, likely owing to stronger microzooplankton grazing and bacterial activity. The degree of iron co-limitation correlated to bSiO 2 growth rates (V Si , d -1 ). Highest rates were observed in the SAZ, southeast of Tasmania, a region influenced by iron-enriched East Australian Current water advecting through the Subtropical Front. The diatom communities appeared differently adapted and conditioned, in terms of uptake ability, for growth under low Si(OH) 4 availability. Combining our results with existing bSiO 2 dissolution and production data, we estimate a spring to summer net bSiO 2 production for the circumpolar SAZ and PFZ regions of 7.4 and 3.6 Tmol yr -1 , respectively, representing 4.3 and 2.1% of the global net bSiO 2 production for each region. Furthermore, a clear seasonal pattern emerges with (1) higher bSiO 2 production in spring (0.9 to 12.7 and 6.8 to 60.7 mmol Si m -2 d -1 for the SAZ and PFZ, respectively) compared to summer (0.1 to 6.6 and 0.3 to 9.1 mmol Si m -2 d -1 for the SAZ and PFZ, respectively) and (2) a bSiO 2 dissolution to production ratio of <1 in spring (~0.4) and generally >1 in summer (~1.7).

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Resource limitation of phytoplankton growth in the Crozet Basin, Subantarctic Southern Ocean

Cited by 67 publications

References 63 publications

Spatial and Temporal Variations in Environmental Variables in Relation to Phytoplankton Community Structure in a Eutrophic River-Type Reservoir

Spatial and Temporal Variations in Environmental Variables in Relation to Phytoplankton Community Structure in a Eutrophic River-Type Reservoir

Primary production in the Sub-Antarctic and Polar Frontal Zones south of Tasmania, Australia; SAZ-Sense survey, 2007

Efficient silicon recycling in summer in both the Polar Frontal and Subantarctic Zones of the Southern Ocean

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