A subsurface particle maximum layer and enhanced microbial activity in the secondary nitrite maximum of the northeastern tropical Pacific Ocean

Garfield, Paula C.; Packard, Theodore T.; Friederich, Gernot; Codispoti, Louis A

doi:10.1357/002224083788520496

Cited by 64 publications

(41 citation statements)

References 27 publications

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“…Intermediate depth particles maxima (revealed by light transmission) have been observed earlier in OMZ off the Peruvian coast (Pak et al, 1980;Whitmire et al, 2009), off Mexico (Garfield et al, 1983), in the Cariaco basin of the Gulf of Mexico (Taylor et al, 2001), and in the Indian Ocean Shailaja, 2001). However, these studies could not unambiguously identify the nature and sources of these INL (local production vs. advective transport).…”

Section: Biological Processes In Intermediate and Deep Nepheloid Layersmentioning

confidence: 80%

“…However, in this study, INL and DNL do not appear to be confined to a specific water mass as it occurs over a wide density range (respectively σ -θ 26-27 kg m −3 and 27.4-27.6 kg m −3 ). Garfield et al (1983) proposed that the presence of denitrifying and ammonium oxidizing bacteria could partly explain the persistence of a subsurface particle maximum in the Pacific OMZ. In the Arabian OMZ, and Naqvi (1994) indicated, from optical measurements, that the particle maxima does not exhibit a systematic onshore-offshore gradient expected from an off-shore transport of the bottom nepheloid layer detaching from the .…”

Section: Biological Processes In Intermediate and Deep Nepheloid Layersmentioning

confidence: 99%

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Particle size distribution and estimated carbon flux across the Arabian Sea oxygen minimum zone

et al. 2014

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Abstract. The goal of the Arabian Sea section of the TARA oceans expedition was to study large particulate matter (LPM > 100 µm) distributions and possible impact of associated midwater biological processes on vertical carbon export through the oxygen minimum zone (OMZ) of this region. We propose that observed spatial patterns in LPM distribution resulted from the timing and location of surface phytoplankton bloom, lateral transport, microbial processes in the core of the OMZ, and enhanced biological processes mediated by bacteria and zooplankton at the lower oxycline. Indeed, satellite-derived net primary production maps showed that the northern stations of the transect were under the influence of a previous major bloom event while the most southern stations were in a more oligotrophic situation. Lagrangian simulations of particle transport showed that deep particles of the northern stations could originate from the surface bloom while the southern stations could be considered as driven by 1-D vertical processes. In the first 200 m of the OMZ core, minima in nitrate concentrations and the intermediate nepheloid layer (INL) coincided with high concentrations of 100 µm < LPM < 200 µm. These particles could correspond to colonies of bacteria or detritus produced by anaerobic microbial activity. However, the calculated carbon flux through this layer was not affected. Vertical profiles of carbon flux indicate low flux attenuation in the OMZ, with a Martin model b exponent value of 0.22. At three stations, the lower oxycline was associated to a deep nepheloid layer, an increase of calculated carbon flux and an increase in mesozooplankton abundance. Enhanced bacterial activity and zooplankton feeding in the deep OMZ is proposed as a mechanism for the observed deep particle aggregation. Estimated lower flux attenuation in the upper OMZ and re-aggregation at the lower oxycline suggest that OMZ may be regions of enhanced carbon flux to the deep sea relative to non OMZ regions.

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Section: Biological Processes In Intermediate and Deep Nepheloid Layersmentioning

confidence: 80%

Section: Biological Processes In Intermediate and Deep Nepheloid Layersmentioning

confidence: 99%

Particle size distribution and estimated carbon flux across the Arabian Sea oxygen minimum zone

et al. 2014

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“…However, the patterns by which microbial physiological traits are distributed between particleassociated and free-living communities are not well understood for many ocean regions. Characterizing particle-associated microbes may be especially important in OMZs, where local particle maxima have been positively related to both oxygen depletion (Garfield et al, 1983;Whitmire et al, 2009) and microbial metabolic activity (Naqvi et al, 1993).…”

Section: Resultsmentioning

confidence: 99%

Metagenomic analysis of size-fractionated picoplankton in a marine oxygen minimum zone

et al. 2013

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Marine oxygen minimum zones (OMZs) support diverse microbial communities with roles in major elemental cycles. It is unclear how the taxonomic composition and metabolism of OMZ microorganisms vary between particle-associated and free-living size fractions. We used amplicon (16S rRNA gene) and shotgun metagenome sequencing to compare microbial communities from large (41.6 lm) and small (0.2-1.6 lm) filter size fractions along a depth gradient in the OMZ off Chile. Despite steep vertical redox gradients, size fraction was a significantly stronger predictor of community composition compared to depth. Phylogenetic diversity showed contrasting patterns, decreasing towards the anoxic OMZ core in the small size fraction, but exhibiting maximal values at these depths within the larger size fraction. Fraction-specific distributions were evident for key OMZ taxa, including anammox planctomycetes, whose coding sequences were enriched up to threefold in the 0.2-1.6 lm community. Functional gene composition also differed between fractions, with the 41.6 lm community significantly enriched in genes mediating social interactions, including motility, adhesion, cell-to-cell transfer, antibiotic resistance and mobile element activity. Prokaryotic transposase genes were three to six fold more abundant in this fraction, comprising up to 2% of protein-coding sequences, suggesting that particle surfaces may act as hotbeds for transposition-based genome changes in marine microbes. Genes for nitric and nitrous oxide reduction were also more abundant (three to seven fold) in the larger size fraction, suggesting microniche partitioning of key denitrification steps. These results highlight an important role for surface attachment in shaping community metabolic potential and genome content in OMZ microorganisms.

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“…Deep particulate and microbial (bacterial) biomass maxima have been reported from various coastal and oceanic regions ( Sorokin 1964, Holm-Hansen & Booth 1966, Pomeroy & Johannes 1968, Devol et al 1976, Karl & Holm-Hansen 1978, Garfield et al 1983). The ultimate source of nutrition for the bacteria at these depths is probably derived from organic particles which have either settled out of the surface waters or have been advected into the region.…”

Section: Discussionmentioning

confidence: 99%

A deep protozoan maximum in the Gulf of Maine

Townsend¹,

Cammen²

1985

Mar. Ecol. Prog. Ser.

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We found a deep maximum In the abundance of larger protozoans (>35 wm) in the Gulf of Maine at depths from 55 to 100 m, which was well below the euphotic zone, pycnocline, and the depths of peak biomass and production of both phytoplankton and b a c t e r~a .Our calculations of the energetics of these protozoan populations suggest that they are unable to obtain sufficient nutrition from local microbial production. We discuss the possibility that organic material, which settles out of the surface layer, might collect at a deep hydrographic anomaly and sustaln the protozoans in the deep maximum.

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A subsurface particle maximum layer and enhanced microbial activity in the secondary nitrite maximum of the northeastern tropical Pacific Ocean

Cited by 64 publications

References 27 publications

Particle size distribution and estimated carbon flux across the Arabian Sea oxygen minimum zone

Particle size distribution and estimated carbon flux across the Arabian Sea oxygen minimum zone

Metagenomic analysis of size-fractionated picoplankton in a marine oxygen minimum zone

A deep protozoan maximum in the Gulf of Maine

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