Longitudinal and Vertical Variations of Dissolved Labile Phosphoric Monoesters and Diesters in the Subtropical North Pacific

The labile fraction of dissolved organic phosphorus (DOP) – predominantly consisting of phosphoric esters – is an important microbial P source in the subtropical oligotrophic ocean. However, unlike phosphate, knowledge for labile DOP is still limited due to the scarcity of broad and intensive observations. In this study, we examined the concentrations and size-fractionated hydrolysis rates of labile phosphoric monoesters and diesters along a >10,000 km longitudinal transect in the North Pacific (23°N; upper 200-m layer). Depth-integrated monoesters decreased westward with a maximum difference of fivefold. Vertical profiles of monoesters in the eastern and western basins showed decreasing and increasing trends with depth, respectively. The monoester-depleted shallow layer of the western basin was associated with phosphate depletion and monoesterase activity was predominant in the large size fraction (>0.8 μm), suggesting that monoesters are significant P sources particularly for large microbes. In contrast, diester concentrations were generally lower than monoester concentrations and showed no obvious horizontal or vertical variation in the study area. Despite the unclear distribution pattern of diesters, diesterase activity in the particulate fraction (>0.2 μm) increased in the phosphate-depleted shallow layer of the western basin, suggesting that the targeted diesters in the assay were also important microbial P sources. Diesterase activities in the dissolved fraction (<0.2 μm) were not correlated with ambient phosphate concentrations; however, cell-free diesterase likely played a key role in P cycling, as dissolved diesterase activities were substantially higher than those in the particulate fraction. The horizontal and vertical variability of labile monoesters in the subtropical North Pacific were therefore predominantly regulated by P stress in particularly large microbes, whereas the distributions of labile diesters and diesterase activities were generally independent of microbial P stress, indicating a more complex regulation of diesters to that of monoesters.

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Modeling the inorganic phosphorus cycle of the North Pacific using an adjoint data assimilation model to assess the role of dissolved organic phosphorus

Global Biogeochemical Cycles ◽

10.1029/94gb03104 ◽

1995 ◽

Vol 9 (1) ◽

pp. 101-119 ◽

Cited By ~ 39

Author(s):

Richard J. Matear ◽

Greg Holloway

Keyword(s):

Data Assimilation ◽

North Pacific ◽

Organic Phosphorus ◽

Inorganic Phosphorus ◽

Phosphorus Cycle ◽

Dissolved Organic Phosphorus ◽

The North ◽

The North Pacific ◽

Assimilation Model

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Increasing trends for the surface heat flux and fresh water flux in the North Pacific eastern subtropical region

Geophysical Research Letters ◽

10.1029/2011gl047128 ◽

2011 ◽

Vol 38 (10) ◽

pp. n/a-n/a ◽

Cited By ~ 2

Author(s):

Shinsuke Iwasaki ◽

Masahisa Kubota

Keyword(s):

Heat Flux ◽

North Pacific ◽

Surface Heat Flux ◽

Water Flux ◽

Surface Heat ◽

Subtropical Region ◽

The North ◽

Fresh Water Flux ◽

Increasing Trends ◽

The North Pacific

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Deep Atmospheric Response to the North Pacific Oceanic Subtropical Front in Spring

Journal of Climate ◽

10.1175/2008jcli2311.1 ◽

2008 ◽

Vol 21 (22) ◽

pp. 5960-5975 ◽

Cited By ~ 52

Author(s):

Fumiaki Kobashi ◽

Shang-Ping Xie ◽

Naoto Iwasaka ◽

Takashi T. Sakamoto

Keyword(s):

North Pacific ◽

Vertical Structure ◽

Surface Wind ◽

Storm Track ◽

Structure Characteristic ◽

Atmospheric Effects ◽

Western Basin ◽

Subtropical Front ◽

The North ◽

The North Pacific

Abstract The North Pacific subtropical front (STF) is a zone of high sea surface temperature (SST) gradients located around 25°N in the western basin and is most pronounced in spring. The STF’s atmospheric effects are investigated using satellite observations and an atmospheric reanalysis. During April–May along the STF, surface wind stress curl turns weakly cyclonic in the general background of anticyclonic curls. Atmospheric column-integrated water vapor displays a pronounced meridional maximum along this surface trough, suggesting a deep vertical structure. Cyclonic wind curls occur intermittently at intervals of a few days along the STF in subsynoptic low pressure systems accompanying larger, synoptic highs in the main storm track to the north. In the subsynoptic surface lows, convective rain takes place with deep upward motion moistening the entire troposphere. The lows are enhanced by condensational heating, leading to the formation of weak cyclonic wind curls. The lows display vertical structure characteristic of baroclinic instability, suggesting that they are triggered by the passage of synoptic migratory highs and grow on the baroclinicity anchored by the SST front. The cyclonic wind curls appear to be related to a cloud/rainband associated with the so-called pre-baiu/meiyu front in May.

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There and back again – unraveling mechanisms of bacterial biogeography in the North Pacific Subtropical Gyre to and from station ALOHA

10.1101/141085 ◽

2017 ◽

Author(s):

Markus V. Lindh

Keyword(s):

North Pacific ◽

Size Fraction ◽

Single Site ◽

Metapopulation Dynamics ◽

North Pacific Subtropical Gyre ◽

The North ◽

Large Size ◽

Station Aloha ◽

The North Pacific ◽

Large Size Fraction

AbstractBacterially-mediated fluxes of energy and matter are dynamic in time and space coupled with shifts in bacterial community structure. Yet, our understanding of mechanisms shaping bacterial biogeography remains limited. Near-surface seawater was collected during transits between Honolulu and Station ALOHA in the North Pacific Subtropical Gyre to examine the shape of occupancy-frequency distributions (the different number of populations occupying different number of sites) and determine bacterial metapopulation dynamics. Bacterial 16S rRNA gene amplicons were sequenced from whole seawater and filter-size fractionated plankton DNA samples while also separating the community into distinct taxonomic groups at phyla/class and analyzing these compartments separately. For the total seawater (i.e. the >0.2 μm size fraction) and picoplankton communities (i.e. the size fraction >0.2 μm and < 3.0 μm), but not the large size fraction community (i.e. the >3.0 μm size fraction), most individual operational taxonomic units (OTUs) occupied a single site and the number of OTUs occupying different number of sites followed a significant bimodal pattern with several core OTUs occupying all sites. Nevertheless, only Cyanobacteria (in particularProchlorococcussp.) and in a few instances also Alphaproteobacteria (in particular SAR11 clade and Aegan-169 marine group bacteria) exhibited bimodal occupancy-frequency patterns. As expected,Prochlorococcussp. had an inversed bimodal occupancy-frequency distribution with most OTUs found at all sites. Yet, there were individual satellite OTUs affiliated withProchlorococcussp. that were phylogenetically distinct from the core OTUs and only found at a single site. Collectively, these findings indicate that different compartments (size fractions and taxa) have different metapopulation dynamics. Bimodal patterns among the low diversity total and picoplankton communities but not in the high diversity large size fraction suggest that positive feedbacks between local abundance and occupancy are important when environmental conditions are homogenous and diversity is low.

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