High concentrations of marine snow and diatom algal mats in the North Pacific Subtropical Gyre: Implications for carbon and nitrogen cycles in the oligotrophic ocean

Pilskaln, Cynthia H.; Villareal, Tracy A.; Dennett, Mark R.; Darkangelo-Wood, C.; Meadows, Guy

doi:10.1016/j.dsr.2005.08.004

Cited by 57 publications

(52 citation statements)

References 64 publications

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“…, become negatively buoyant under nutrientdepletion and positively buoyant as they take up nitrate (Richardson et al 1996), and are documented down to several hundred meters by direct ROV observations (Pilskaln et al 2005). These characteristics indicate a life cycle vertical migration to deep nitrate pools similar to the non-motile dinoflagellate Pyrocystis (Ballek & Swift 1986), a migration notable for the greater distance (~100 m) than that found in numerous flagellated taxa that migrate in the coastal zone (Kamykowski et al 1978).…”

Section: Introductionmentioning

confidence: 95%

“…To collect the 2003 VPR data set, we employed a recalibrated and tested VPR also used in our 1996 study (Pilskaln et al 2005;Villareal et al 1999b). The VPR package consisted of a CCD video camera synchronized at 30 frames sec -1 to a xenon strobe (600 nm), a video recorder and CTD, all mounted to a tow frame with a rear stabilizing fin (Davis et al 1992).…”

Section: Methodsmentioning

confidence: 99%

“…Initially described as possessing diazotrophic symbionts (Martinez et al 1983), subsequent work found no evidence of diazotrophy (Villareal & Carpenter 1989). Rhizosolenia mats possess mM internal NO 3 -pools , utilize NO 3 -via nitrate reductase (Joseph et al 1997), take up NO 3 -in the dark (Richardson et al 1996), have a δ 15 N (3-4 per mil) similar to the deep NO 3 -pool ), ascend at up to 6.4 m h -1, become negatively buoyant under nutrientdepletion and positively buoyant as they take up nitrate (Richardson et al 1996), and are documented down to several hundred meters by direct ROV observations (Pilskaln et al 2005). These characteristics indicate a life cycle vertical migration to deep nitrate pools similar to the non-motile dinoflagellate Pyrocystis (Ballek & Swift 1986), a migration notable for the greater distance (~100 m) than that found in numerous flagellated taxa that migrate in the coastal zone (Kamykowski et al 1978).…”

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confidence: 99%

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Upward nitrate transport by phytoplankton in oceanic waters: balancing nutrient budgets in oligotrophic seas

Villareal

Pilskaln

Montoya

et al. 2014

Preprint

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In oceanic gyres, primary producers are numerically dominated by small (1-5 µm diameter) pro-and eukaryotic cells that primarily utilize recycled nutrients produced by rapid grazing turnover in a highly efficient microbial loop. Continuous losses of nitrogen to depth by sinking, either as single cells, aggregates or fecal pellets, are balanced by both nitrate inputs at the base of the euphotic zone and nitrogen-fixation. This input of N (new nitrogen) to balance export losses (the biological pump) is a fundamental aspect of nitrogen cycling and central to understanding carbon fluxes in the ocean. In the Pacific Ocean, detailed nitrogen budgets at the time-series station HOT require upward transport of nitrate from the nutricline (80-100 m) into the surface layer (~0-40 m) to balance productivity and export needs. However, concentration gradients are negligible and cannot support the fluxes. Physical processes can inject nitrate into the base of the euphotic zone, but the mechanisms for transporting this nitrate into the surface layer across many 10s of m in highly stratified systems are unknown.In these seas, vertical migration by the very largest 10 2 -10 3 µm diameter) phytoplankton is common as a survival strategy to obtain nitrogen from sub-euphotic zone depths. This vertical migration is driven by buoyancy changes rather than by flagellated movement and can provide upward nitrogen transport as nitrate (mM concentrations) in the cells. However, the contribution of vertical migration to nitrate transport has been difficult to quantify over the required basin scales. In this study, we use towed optical systems and isotopic tracers to PrePrintsIntroduction Nitrogen in the euphotic zone of the open sea has long been recognized to partition into two distinct pools of availability (Dugdale & Goering 1967). New nitrogen represents introduction of N from outside the euphotic zone, either in the form of deep NO 3 -or nitrogenfixation, while regenerated N results from consumption and remineralization of dissolved or particulate N (Dugdale & Goering 1967). While regenerated N dominates the total phytoplankton uptake, new N is critical to balance losses due to vertical fluxes and is linked to total system productivity (Eppley & Peterson 1979). This has been expressed as the f ratio where 'f' = new/total N uptake and ranges from 0-1. On longer time scales, new N input must balance sedimentary losses or the system will experience net losses of nitrogen (Eppley & Peterson 1979). The surface waters of the open ocean are considered low 'f' ratio environments: N and P often occur at nM concentrations, and ammonium is the dominant form taken up by phytoplankton (Lipschultz et al. 1996;Raimbault et al. 2008;Wu et al. 2000). The f ratio increases in the light-limited lower depths of the euphotic zone due to the increased availability of nitrate at the nutricline, thus creating what has been recognized as a two-layered structure (Goldman 1988). This general pattern can be modified in regions of low iron input, where iron ava...

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Section: Introductionmentioning

confidence: 95%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Upward nitrate transport by phytoplankton in oceanic waters: balancing nutrient budgets in oligotrophic seas

Villareal

Pilskaln

Montoya

et al. 2014

Preprint

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“…Little is known directly about the feeding behavior of leptocephali in nature, but based on scanning electron microscope observations of gut contents (Otake et al 1993, Mochioka & Iwamizu 1996 and stable nitrogen isotope analysis (Otake 1996), the diet of leptocephali is thought to be organic detritus, which is often referred to as 'marine snow' and composed of material such as fecal pellets, discarded larvacean houses and plankton remains (Mochioka & Iwamizu 1996). In general, particulate organic carbon that includes marine snow and other particles exhibits maximum concentrations in the upper 100 m layer of the North Pacific subtropical gyre and along its western margins, and decreases sharply at deeper depths because the particles are produced in the euphotic layer near the sea surface and most are consumed by various organisms or decomposed by bacteria before reaching deeper layers (Ichikawa & Nishizawa 1975, Ichikawa 1982, Hebel & Karl 2001, Pilskaln et al 2005. This suggests that the food of leptocephali is most abundant at depths shallower than 100 m. Previous field data indicated that small Japanese eel leptocephali (10 to 20 mm TL) were distributed from 50 to 100 m (27 to 29°C) at night, and from 100 to 150 m (24 to 27°C) in the day (Otake et al 1998).…”

Section: Ecological Significancementioning

confidence: 99%

Ontogenetic changes in phototactic behavior during metamorphosis of artificially reared Japanese eel Anguilla japonica larvae

Yamada¹,

Okamura²,

Mikawa³

et al. 2009

Mar. Ecol. Prog. Ser.

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“…Marine aggregates constitute up to 63% of the total particulate organic carbon in some parts of the ocean (Alldredge 1979), and could be important for carbon sequestration even in oligotrophic waters (BenitezNelson et al 2001, Pilskaln et al 2005. Marine aggregates are often sites of elevated heterotrophic activity (Silver et al 1978, Caron et al 1982, Alldredge & Gottschalk 1990, Artolozaga et al 1997, Dilling et al 1998, and colonization and subsequent solubilization of aggregates by bacteria can influence biogeochemical cycling of organic matter (Cho & Azam 1988, Smith et al 1992.…”

Section: Introductionmentioning

confidence: 99%

Effects of starvation on aggregate colonization and motility of marine bacteria

Yam¹,

Tang²

2007

Aquat. Microb. Ecol.

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Fluxes of particulate matter to depth and dynamics of dissolved organic matter in the water column are influenced by microbial processes associated with organic aggregates like marine snow. These microscale processes include the encounter between bacteria and aggregates, which has been previously modeled and tested with well-fed and actively growing bacteria. In the present study, we investigated the effects of starvation on initial bacterial colonization of aggregates by measuring colonization and detachment of 6 isolates in different physiological states (fed vs. starved) using model aggregates. Because aggregate encounter depends on motility, the motility behaviors of fed and starved bacteria of 3 selected strains were also compared using image analysis. All 6 fed isolates colonized faster and achieved significantly higher steady-state abundances on model aggregates than those that were starved. However, there was no difference in detachment rates between fed and starved bacteria. The 3 selected strains had significantly lower average swimming speeds when starved. Diffusivities calculated from motilities of 2 starved isolates were more than 6 times lower than those of their fed counterparts. Our results show that starvation significantly affects bacterial behavior and bacteria-aggregate interactions, which may lead to differences in particulate and dissolved organic matter fluxes and cycling under different productivity regimes.

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High concentrations of marine snow and diatom algal mats in the North Pacific Subtropical Gyre: Implications for carbon and nitrogen cycles in the oligotrophic ocean

Cited by 57 publications

References 64 publications

Upward nitrate transport by phytoplankton in oceanic waters: balancing nutrient budgets in oligotrophic seas

Upward nitrate transport by phytoplankton in oceanic waters: balancing nutrient budgets in oligotrophic seas

Ontogenetic changes in phototactic behavior during metamorphosis of artificially reared Japanese eel Anguilla japonica larvae

Effects of starvation on aggregate colonization and motility of marine bacteria

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