Distribution and composition of biogenic particulate matter in a Gulf Stream warm-core ring

Nelson, David M.; Ducklow, Hugh W.; Hitchcock, Gary L.; Brzezinski, Mark A.; Cowles, Timothy J.; Garside, C.; Gould, Richard; Joyce, Terrence M.; Langdon, C.; McCarthy, James J.; Yentsch, Charles S.

doi:10.1016/0198-0149(85)90052-4

Cited by 53 publications

(28 citation statements)

References 36 publications

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“…or in November 1989 (10 mg m-'; Krom et al 1992). This pattern has been found previously for other warm-core eddies (Tranter et al 1980, Bradford et al 1982, Jeffrey & Hallegraeff 1987 and rings (Nelson et al 1985).…”

Section: Discussionsupporting

confidence: 64%

Buildup of microbial biomass during deep winter mixing in a Mediterranean warm-core eddy

Zohary¹,

Brenner²,

Krom³

et al. 1998

Mar. Ecol. Prog. Ser.

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The Cyprus Eddy, a warm-core eddy southeast of Cyprus, was sampled towards the end of an exceptionally cold winter in early March 1992, within 4 d of a storm and w~thin 24 h of an intrusion of cold air. Depth profiles of temperature, salinity and dissolved nutrients showed an active deep mixed layer from the surface to ca 500 m at the core of the eddy, while at the eddy boundaries the mixed layer extended only to 150 m. Microb~al populations were evenly distributed over the entire upper 500 m at the core station, as iiidicated by chlorophy!! and high performance liquid chromatography (HPLC)-determined pigment composition, by flow-cytometric analysis of the ultraphytoplankton, by direct counts of 4',6-diam~dino-2-phenylindole (DAP1)-stained bacter~a and %-thymidine measurements of bacterial activity. As far as we know, thls is the first deta~led description of the microbial populations in a warm-core eddy during the bloom season. The integrated water column chlorophyll content, 59 mg m-2 at the core and 45.5 mg m-2 at the boundary, was more than double the typical late autumn values, suggesting a bloom was occurring. Noticeably, this bloom was not delayed until the establishment of summer stratification as has been observed previously in warm-core eddies. While theoretical considerations based on the calculated critical depth at the core of about 300 m suggested that a bloom should not have occurred, our data jointly with previous data from the Cyprus Eddy support the hypothesis that interim periods of quiescence between mixlng events enable bloom development even when the mixing depth is greater than the critical depth. Added nutrients and dilution of grazers, both resulting from the deep mixing, probably contributed jointly to the enhanced productivity. Based on phytoplankton 11ght-shade adaptation features and cellular chlorophyll fluorescence per cell, we calculated that the rate of vertical mixing in the core was at least 30 m h-'

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Section: Discussionsupporting

confidence: 64%

Buildup of microbial biomass during deep winter mixing in a Mediterranean warm-core eddy

Zohary¹,

Brenner²,

Krom³

et al. 1998

Mar. Ecol. Prog. Ser.

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“…Since the shelf water is generally denser than ambient slope water, the densest shelf water in the filament will appear as a subsurface core in observational cross sections. Observations of subsurface cores of 32 psu, 108C water, typical of near-bottom cold pool shelf water (Houghton et al 1982), are common (e.g., Nelson et al 1985;Tang et al 1985;Ramp et al 1983;Garfield and Evans 1987). These cores are outside the eddy.…”

Section: B Observational Evidencementioning

confidence: 99%

Offshore Transport of Shelf Water by Deep-Ocean Eddies

Cherian

Brink

2016

Journal of Physical Oceanography

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At continental margins, energetic deep-ocean eddies can transport shelf water offshore in filaments that wrap around the eddy. One example is that of Gulf Stream warm-core rings interacting with the Mid-Atlantic Bight shelf. The rate at which shelf water is exported in these filaments is a major unknown in regional budgets of volume, heat, and salt. This unknown transport is constrained using a series of idealized primitive equation numerical experiments wherein a surface-intensified anticyclonic eddy interacts with idealized shelf-slope topography. There is no shelfbreak front in these experiments, and shelf water is tracked using a passive tracer. When anticyclones interact with shelf-slope topography, they suffer apparent intrusions of shelf-slope water, resulting in a subsurface maximum in offshore transport. The simulations help construct an approximate model for the filament of exported water that originates inshore of any given isobath. This model is then used to derive an expression for the total volume of shelf-slope water transported by the eddy across that isobath. The transport scales with water depth, radius, and azimuthal velocity scale of the eddy. The resulting expression can be used with satellite-derived eddy properties to estimate approximate real-world transports ignoring the presence of a shelfbreak front. The expression assumes that the eddy's edge is at the shelf break, a condition not always satisfied by real eddies.

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“…See Fig. 1 1985, Garside 1985, Joyce & Stalcup 1985, Nelson et al 1985 (Fox et al 1983); (2) In April, ring 82-B had recently undergone deep convective mixing (Joyce & Stalcup 1985) and silicic acid concentrations were vertically uniform at 2.5 to 2.9 pM throughout the upper 300 m. Nitrate and phosphate were also vertically uniform at concentrations of 5.1 and 0.25 PM, respectively (Fox et al 1984a); (3) Ring 82-B became thermally stratified some time in May and was strongly stratified by mid June (Evans et al 1985, Nelson et al 1985. Silicic acid, nitrate and phosphate were all depleted to colorimetrically undetectable levels throughout the surface layer (Fox et al 1984b) although a much more sensitive chemiluminescent analysis showed nitrate to be present at > 10 nM at all times (Garside 1985).…”

Section: Discussionmentioning

confidence: 99%

“…For each experiment we collected a 60 I seawater sample from the depth to which 60 % of the surface irradiance penetrated (3 to 5 m), as described by Nelson et al (1985). Irradiance at this depth ranged from 365 to 2000 PE m-2 S-' (Phinney et al 1983(Phinney et al , 1984 and this depth was chosen on the expectation that light should be neither strongly limiting nor strongly inhibiting to photosynthesis.…”

Section: Methodsmentioning

confidence: 99%

Kinetics of silicic acid uptake by natural diatom assemblages in two Gulf Stream warm-core rings

Dm¹,

Brzezinski²

1990

Mar. Ecol. Prog. Ser.

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We performed "Si tracer experiments to measure the uptake rates of silicic acid by natural diatom assemblaged in 2 Gulf Stream warm-core rings as a function of the extracellular silicic acid concentration. The experiments were performed a t and near the centers of rings 81-D and 82-B, and lncluded 5 sampling dates in late spring, summer and autumn, when silicic acid was undetectable to conventional analyses (< 0.2 yM) throughout the upper 20 to 30 m Uptake was measurably substratelimited only at those stations where silicic acid was undetectable. Concentrations of 2.5 to 3 1rM Si(OH)4, which typlfied ring 82-B before the development of the seasonal thermocline, were high enough to support maximum uptake rates. When substrate 1i.mitation was present the dependence of the uptake rate on sllicic acid concentration exhibited hyperbolic saturation kinetics, with half-saturation constants (K,) ranging from 0.53 to 0.90 \&M. This range is considerably lower than that reported previously for natural diatom asselnblages (1.5 to 3.7 pM). A numerical sllnulation indicates that a diatom species with a K, value typical of the ring assemblages would outcompete most diatom species whose silicon kinetics have been examined in culture, not only under conditions of continuously low sll~cic a c~d concentration but with the sporadic, pulsed nutrient injections that appear to characterne warm-core ocean eddies. Prevlous studies of silicic acid uptake kinetics in natural waters have all been conducted In relatively nutnent-rlch systems and the lower K, values we report here for 2 Gulf Stream warm-core rings Indicate that diatoms growing in severely nutrient-depleted surface waters have a higher afflnlty for slliclc acid than those growing in more eutrophic habitats. If this is true for other nutrient-depleted environments such as the tropics and mid-ocean gyres, the likelihood of significant slhcon limitation in such systems is diminished.

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Distribution and composition of biogenic particulate matter in a Gulf Stream warm-core ring

Cited by 53 publications

References 36 publications

Buildup of microbial biomass during deep winter mixing in a Mediterranean warm-core eddy

Buildup of microbial biomass during deep winter mixing in a Mediterranean warm-core eddy

Offshore Transport of Shelf Water by Deep-Ocean Eddies

Kinetics of silicic acid uptake by natural diatom assemblages in two Gulf Stream warm-core rings

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