Nitrate use by plankton in the eastern subtropical North Atlantic, March‐April 1989

Eppley, Richard W.; Koeve, Wolfgang

doi:10.4319/lo.1990.35.8.1781

Cited by 37 publications

(12 citation statements)

References 11 publications

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“…À uptake with depth, are a common observation in subtropical waters [e.g., Eppley and Koeve, 1990;Eppley and Renger, 1992;Allen et al, 1996;Varela et al, 2005]. However, as light-dependent photosynthetic rates are typically highest in surface waters [Maranon et al, 2000;Poulton et al, 2006], there is a vertical separation between the region of the water column primarily involved in NO 3 À uptake and that involved in carbon fixation.…”

Section: Nitrate Uptakementioning

confidence: 99%

“…[15] Previous examples of high NO 3 À uptake, or uptake in excess of local production requirements, at the nitracline are known [Eppley and Renger, 1986;Eppley and Koeve, 1990;Eppley and Renger, 1992;Allen et al, 1996;Varela et al, 2005]. Suggested causes for this observation include (1) heterotrophic bacterial uptake [Eppley and Renger, 1992], (2) transiently or permanently decoupled algal C:N uptake ratios [Eppley and Renger, 1986;Banse, 1994;Anderson and Pondaven, 2003;Falkowski and Davis, 2004;Christian, 2005], (3) uptake by vertically migrating species of phytoplankton such as Rhizosolenia spp.…”

Section: Deep Nitrate Uptakementioning

confidence: 99%

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Nitrate uptake at photic zone depths is not important for export in the subtropical ocean

Painter

Sanders

Poulton

et al. 2007

Global Biogeochemical Cycles

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[1] Observations of nitrate (NO 3 À ) uptake across the photic zone of the tropical and subtropical Atlantic Ocean are described. High NO 3 À uptake rates were commonly found at depth (>75 m), coincident with the deep chlorophyll maximum and the nitracline, whereas highest rates of carbon fixation were found in near-surface waters (0À50 m). Thus NO 3 À based estimates of in situ new production (NO 3 À uptake Â 6.6) at depth are in excess of in situ measurements of carbon fixation implying NO 3 À uptake exceeds production requirements. Such surplus NO 3 À uptake may ultimately result in the production of dissolved organic nitrogen with its measurement within the particulate phase representing a transient enrichment. When only upper euphotic zone (to 14% irradiance depth) rates of NO 3 À uptake and carbon fixation are considered, new production is less than total carbon fixation, suggesting, as expected, that additional nitrogen sources are required to support the observed production levels. Comparison of the deep NO 3 À uptake rates with literature estimates of seasonal NO 3 À drawdown within the nitracline suggests that the drawdown observed represents only 1% of the actual NO 3 À uptake occurring in this region of the water column, and hence most NO 3 À uptake must be recycled locally rather than exported.

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Section: Nitrate Uptakementioning

confidence: 99%

Section: Deep Nitrate Uptakementioning

confidence: 99%

Nitrate uptake at photic zone depths is not important for export in the subtropical ocean

Painter

Sanders

Poulton

et al. 2007

Global Biogeochemical Cycles

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“…At the base of the euphotic zone, however, a number of studies have reported enhanced rates of nitrate uptake indicative of algal growth on a deep nitrate (NO 3 − ) reservoir (King & Devol 1979, Le Bouteiller 1986, Lewis et al 1986, Eppley & Koeve 1990, Painter et al 2007). Infrequent observation of this NO 3 − uptake maximum has not prevented recognition of a deep perennial layer of new production in the subtropical ocean (Ward et al 1989, Harrison 1990).…”

Section: Introductionmentioning

confidence: 99%

Picoeukaryote distribution in relation to nitrate uptake in the oceanic nitracline

Painter¹,

Patey²,

Tarran³

et al. 2014

Aquat. Microb. Ecol.

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We investigated the relationship between picoeukaryote phytoplankton (< 2 µm) and the deep layer of new production (NO 3 − uptake) in the nitracline of the eastern subtropical North Atlantic Ocean. Indices of NO 3 − uptake kinetics obtained within the lower 15% of the euphotic zone demonstrate that subsurface NO 3 − uptake maxima are coincident with localised peaks in maximum uptake rates (V max ) and, crucially, with maximum picoeukaryote abundance. The mean rate of NO 3 − utilization at the nitracline is typically 10-fold higher than in surface waters despite much lower in situ irradiance. These observations confirm a high affinity for NO 3 − , most likely by the resident picoeukaryote community, and we conservatively estimate mean cellular uptake rates of between 0.27 and 1.96 fmol NO 3 − cell −1 h −1. Greater scrutiny of the taxonomic composition of the picoeukaryote group is required to further understand this deep layer of new production and its importance for nitrogen cycling and export production, given longstanding assumptions that picoplankton do not contribute directly to export fluxes.

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“…A recently reported unexpected nitrate distribution in the euphotic zone (EPPLEY and KOEVE, 1990) at 18°N, 30°W has been related to the occurrence of subsurface salinity maximum water at the base of the euphotic zone (PODEWSKI et al, 1993). In this paper wc attempt to relate observed variability in new production rates in the area (EPPEEY el a[.. 1990;EPPLEY and KOEVE, 1990) to hydrographical and chemical patterns within the uppe, r 200 m which were influenced by the frequent occurrence of Sm~ × water.…”

mentioning

confidence: 99%

“…In this paper wc attempt to relate observed variability in new production rates in the area (EPPEEY el a[.. 1990;EPPLEY and KOEVE, 1990) to hydrographical and chemical patterns within the uppe, r 200 m which were influenced by the frequent occurrence of Sm~ × water.…”

mentioning

confidence: 99%

An unexpected nitrate distribution in the tropical North Atlantic at 18°N, 30°W—implications for new production

Koeve

Eppley²,

Podewski

et al. 1993

Deep Sea Research Part II: Topical Studies in Oceanography

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Abstract--During a R.V. Meteor JGOFS-NABE cruise to a tropical site in the northeast Atlantic in spring 1989, three different vertical regimes with respect to nitrate distribution and availability within the euphotic zone were observed. Besides dramatic variations in the depth of the nitractine. a previously undescribed nose-like nitrate maximum within the euphotic zone was the most prominent feature during this study. Both the vertical structure of phytoplankton biomass and the degree of absolute and relative new production were related to the depth of the nitracline, which in turn was dependent on the occurrence/non-occurrence of the subsurface subtropical salinity maximum (Sm,~x). The mesoscale variability of the nitracline depth, as indicated from a pre-survey grid, and published data on the frequent occurrence of the Sm~ × in tropical waters suggest higher variability of new production and F-ratio than usually expected for oligotrophic oceans. The importance of salt fingering and double diffusion for nitrate transport into the euphotic zone is discussed.

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Nitrate use by plankton in the eastern subtropical North Atlantic, March‐April 1989

Cited by 37 publications

References 11 publications

Nitrate uptake at photic zone depths is not important for export in the subtropical ocean

Nitrate uptake at photic zone depths is not important for export in the subtropical ocean

Picoeukaryote distribution in relation to nitrate uptake in the oceanic nitracline

An unexpected nitrate distribution in the tropical North Atlantic at 18°N, 30°W—implications for new production

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