Spatial variability of the primary production and chlorophyll a concentration in the drake passage in the austral spring

Демидов, А. Б.; Мошаров, С. А.; Гагарин, В. И.; Romanova, N. D.

doi:10.1134/s0001437011020056

Cited by 10 publications

(7 citation statements)

References 51 publications

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“…Nevertheless, the DP is not considered an area of intensive phytoplankton growth, as illustrated by low chlorophyll a concentrations (Fig. 1; Demidov et al, 2011). Primary production is characterized by phytoplankton blooms in austral spring (Demidov et al, 2011), when Fe availability is the critical factor for the occurrence of the blooms (De Baar et al, 1995).…”

Section: Study Areamentioning

confidence: 99%

“…1; Demidov et al, 2011). Primary production is characterized by phytoplankton blooms in austral spring (Demidov et al, 2011), when Fe availability is the critical factor for the occurrence of the blooms (De Baar et al, 1995). Additionally, a lack of dissolved silica compared to phosphorus may limit the growth of siliceous phytoplankton species north of the PF (mainly diatoms, Demidov et al, 2011;Freeman et al, 2019).…”

Section: Study Areamentioning

confidence: 99%

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Variations in export production, lithogenic sediment transport and iron fertilization in the Pacific sector of the Drake Passage over the past 400 kyr

et al. 2022

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Abstract. Changes in Southern Ocean export production have broad biogeochemical and climatic implications. Specifically, iron fertilization likely increased subantarctic nutrient utilization and enhanced the efficiency of the biological pump during glacials. However, past export production in the subantarctic southeastern Pacific is poorly documented, and its connection to Fe fertilization, potentially related to Patagonian Ice Sheet dynamics, is unknown. We report biological productivity changes over the past 400 kyr, based on a combination of 230Thxs-normalized and stratigraphy-based mass accumulation rates of biogenic barium, organic carbon, biogenic opal and calcium carbonate as indicators of paleo-export production in a sediment core upstream of the Drake Passage (57.5∘ S, 70.3∘ W). In addition, we use fluxes of iron and lithogenic material as proxies for terrigenous input, and thus potential micronutrient supply. Stratigraphy-based mass accumulation rates are strongly influenced by bottom-current dynamics, which result in variable sediment focussing or winnowing at our site. Carbonate is virtually absent in the core, except during peak interglacial intervals of the Holocene, and Marine Isotope Stages (MIS) 5 and 11, likely caused by transient decreases in carbonate dissolution. All other proxies suggest that export production increased during most glacial periods, coinciding with high iron fluxes. Such augmented glacial iron fluxes at the core site were most likely derived from glaciogenic input from the Patagonian Ice Sheet promoting the growth of phytoplankton. Additionally, glacial export production peaks are also consistent with northward shifts of the Subantarctic and Polar Fronts, which positioned our site south of the Subantarctic Front and closer to silicic acid-rich waters of the Polar Frontal Zone. However, glacial export production near the Drake Passage was lower than in the Atlantic and Indian sectors of the Southern Ocean, which may relate to complete consumption of silicic acid in the study area. Our results underline the importance of micro-nutrient fertilization through lateral terrigenous input from South America rather than eolian transport and exemplify the role of frontal shifts and nutrient limitation for past productivity changes in the Pacific entrance to the Drake Passage.

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Section: Study Areamentioning

confidence: 99%

Section: Study Areamentioning

confidence: 99%

Variations in export production, lithogenic sediment transport and iron fertilization in the Pacific sector of the Drake Passage over the past 400 kyr

et al. 2022

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“…The DP is the region of the SO with the largest vertical velocities associated with topographically induced upwelling (Graham 115 et al, 2015). Nevertheless, the DP is not considered an area of intensive phytoplankton growth, as illustrated by low chlorophyll concentrations (Fig 1; Demidov et al, 2011). Primary production is characterized by phytoplankton blooms in austral spring (Demidov et al, 2011), when Fe availability is the critical factor for the occurrence of the blooms (De Baar et al, 1995).…”

Section: Study Areamentioning

confidence: 99%

“…Additionally, a lack of dissolved silica compared to phosphorous may limit the growth of siliceous phytoplankton species north of the PF (mainly diatoms, Demidov et al, 2011;Freeman et al, 2019). An analysis of the composition of the surface sediments 120…”

Section: Study Areamentioning

confidence: 99%

“…In contrast with this glacial scenario, increases in bottom current strength, usually during interglacials, indicate that the SAF was located south of our site, resulting in a production regime similar to present-day conditions. This area is characterized by low average chlorophyll-a concentrations (Fig 1b), where the lack of dissolved silica may limit the growth of diatoms (Demidov et al, 2011;Freeman et al, 2019), Fig 6a and 6b) and might cause coccolithophores and other phytoplankters to become the dominant group (Rigual Hernández et al, 2020;Saavedra-Pellitero et al, 2019). However, the absence of peaks 465 in the TOC and Ba xs MAR during the Holocene and MIS 5 suggest that the increased CaCO 3 export production did not impact significantly in the integrated proxies of export production, implying that export production by calcareous organisms was too small to have a noticeable impact on the total export during such intervals (Fig 3) Unlike other interglacials, during MIS 11, a prominent nannofossil ooze, primarily composed of Gephyrocapsa coccolithophore and foraminifera has been reported in the area (Lamy, 2016;Toyos et al, 2020) that is mirrored at our site by 470 CaCO 3 MARs one order of magnitude higher than in the Holocene and in MIS 5, and by increases in the Ba xs and TOC MARs (Fig 3).…”

Section: Drivers Of Local Export Production Patternsmentioning

confidence: 99%

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Variations in export production, lithogenic sediment transport and iron fertilization in the Pacific sector of the Drake Passage over the past 400 ka

Toyos

Winckler

Arz

et al. 2021

Preprint

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Abstract. Changes in Southern Ocean export production have broad biogeochemical and climatic implications. Specifically, iron fertilization likely increased subantarctic nutrient utilization and enhanced the efficiency of the biological pump during glacials. However, past export production in the subantarctic Southeast Pacific is poorly documented, and its connection to Fe fertilization, potentially related to Patagonian Ice Sheet dynamics is unknown. We report on biological productivity changes over the past 400 ka, based on a combination of 230Thxs-normalized and stratigraphy-based mass accumulation rates of biogenic barium, organic carbon, biogenic opal, and calcium carbonate as indicators of paleo-export production in a sediment core upstream of the Drake Passage. In addition, we use fluxes of iron and lithogenic material as proxies for terrigenous matter, and thus potential micronutrient supply. Stratigraphy-based mass accumulation rates are strongly influenced by bottom-current dynamics, which result in variable sediment focussing or winnowing at our site. Carbonate is virtually absent in the core, except during peak interglacial intervals of the Holocene, and Marine Isotope Stages (MIS) 5 and 11, likely caused by transient decreases in carbonate dissolution. All other proxies suggest that export production increased during most glacial periods, coinciding with high iron fluxes. Such augmented glacial iron fluxes at the core site were most likely derived from glaciogenic input from the Patagonian Ice Sheet promoting the growth of phytoplankton. Additionally, glacial export production peaks are also consistent with northward shifts of the Subantarctic and Polar Fronts, which positioned our site south of the Subantarctic Front and closer to silicic acid-rich waters of the Polar Frontal Zone, as well as a with a decrease in the diatom utilization of Si relative to nitrate under Fe-replete conditions. However, glacial export production near the Drake Passage was lower than in the Atlantic and Indian sectors of the Southern Ocean, which may relate to complete consumption of silicic acid in the study area. Our results underline the importance of micro-nutrient fertilization through lateral terrigenous input from South America rather than aeolian transport, and exemplify the role of frontal shifts and nutrient limitation for past productivity changes in the Pacific entrance to the Drake Passage.

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Drake passage-a bottleneck where spatial distribution of the planktonic Ostracoda reflects the dynamic hydrography well

et al. 2022

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Spatial variability of the primary production and chlorophyll a concentration in the drake passage in the austral spring

Cited by 10 publications

References 51 publications

Variations in export production, lithogenic sediment transport and iron fertilization in the Pacific sector of the Drake Passage over the past 400 kyr

Variations in export production, lithogenic sediment transport and iron fertilization in the Pacific sector of the Drake Passage over the past 400 kyr

Variations in export production, lithogenic sediment transport and iron fertilization in the Pacific sector of the Drake Passage over the past 400 ka

Drake passage-a bottleneck where spatial distribution of the planktonic Ostracoda reflects the dynamic hydrography well

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