GLORIA

GEOMAR Library Ocean Research Information Access

X

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Online Resource
    Online Resource
    Stocks and fluxes of biogenic silica in the western oligotrophic equatorial Pacific
    American Geophysical Union (AGU) ; 1999
    In:  Journal of Geophysical Research: Oceans Vol. 104, No. C2 ( 1999-02-15), p. 3357-3367
    Details
    In: Journal of Geophysical Research: Oceans, American Geophysical Union (AGU), Vol. 104, No. C2 ( 1999-02-15), p. 3357-3367
    Abstract: During a cruise along the 165°E meridian (6°N–15°S), distributions of biogenic silica (BSi) and of chlorophyll a were studied. BSi ranged between 10 and 60 nmol L −1 in the nitrate‐depleted surface layer. A deep BSi maximum (DBSiM) layer was located at the base of the photic layer. The high mesoscale variability in BSi distribution is explained as resulting from a combination of physical and chemical forcings. For studying the response of the tropical/equatorial ecosystem to physical forcing, BSi is a more sensitive tracer than chlorophyll a . Daily variations of stocks and fluxes of biogenic silica in the 0–340 m layer were measured at a drifting station during a 5 day experiment at 0°S, 167°E. Displacement of the pycnocline occurred at the drifting station, allowing injection of new nutrients in the photic layer to which the ecosystem reacted by an increase of BSi in the DBSiM layer. We hypothesize that this BSi increase is explained by increased diatom growth (at a rate of 0.6 doublings d −1 ). At this drifting station, sediment traps were deployed below the photic layer (at 125, 175, 240, and 340 m depths) to estimate export fluxes of BSi. They ranged between 60 μmol m −2 d −1 at 125 m and 180 μmol m −2 d −1 at 340 m. Compared to a BSi production of 960 μmol m −2 d −1 measured 1 week later during the same cruise in similar oligotrophic equatorial waters, such low export fluxes suggest that dissolution of BSi might be high in the warm equatorial Pacific waters.
    Type of Medium: Online Resource
    ISSN: 0148-0227
    URL: Article
    DOI: 10.1029/1998JC900037
    Language: English
    Publisher: American Geophysical Union (AGU)
    Publication Date: 1999
    detail.hit.zdb_id: 2033040-6
    detail.hit.zdb_id: 3094104-0
    detail.hit.zdb_id: 2130824-X
    detail.hit.zdb_id: 2016813-5
    detail.hit.zdb_id: 2016810-X
    detail.hit.zdb_id: 2403298-0
    detail.hit.zdb_id: 2016800-7
    detail.hit.zdb_id: 161666-3
    detail.hit.zdb_id: 161667-5
    detail.hit.zdb_id: 2969341-X
    detail.hit.zdb_id: 161665-1
    detail.hit.zdb_id: 3094268-8
    detail.hit.zdb_id: 710256-2
    detail.hit.zdb_id: 2016804-4
    detail.hit.zdb_id: 3094181-7
    detail.hit.zdb_id: 3094219-6
    detail.hit.zdb_id: 3094167-2
    detail.hit.zdb_id: 2220777-6
    detail.hit.zdb_id: 3094197-0
    SSG: 16,13
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 2
    Online Resource
    Online Resource
    Enhancement of phytoplankton biomass leeward of Tahiti as observed by Biogeochemical-Argo floats
    Elsevier BV ; 2020
    In:  Journal of Marine Systems Vol. 204 ( 2020-04), p. 103284-
    Details
    In: Journal of Marine Systems, Elsevier BV, Vol. 204 ( 2020-04), p. 103284-
    Type of Medium: Online Resource
    ISSN: 0924-7963
    URL: Article
    DOI: 10.1016/j.jmarsys.2019.103284
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2020
    detail.hit.zdb_id: 1483106-5
    detail.hit.zdb_id: 1041191-4
    SSG: 14
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 3
    Online Resource
    Online Resource
    Modelling N〈sub〉2〈/sub〉 fixation related to 〈i〉Trichodesmium〈/i〉 sp.: driving processes and impacts on primary production in the tropical Pacific Ocean
    Copernicus GmbH ; 2018
    In:  Biogeosciences Vol. 15, No. 14 ( 2018-07-18), p. 4333-4352
    Details
    In: Biogeosciences, Copernicus GmbH, Vol. 15, No. 14 ( 2018-07-18), p. 4333-4352
    Abstract: Abstract. Dinitrogen fixation is now recognized as one of the major sources of bio-available nitrogen in the ocean. Thus, N2 fixation sustains a significant part of the global primary production by supplying the most common limiting nutrient for phytoplankton growth. The “Oligotrophy to UlTra-oligotrophy PACific Experiment” (OUTPACE) improved the data coverage of the western tropical South Pacific, an area recently recognized as a hotspot of N2 fixation. This new development leads us to develop and test an explicit N2 fixation formulation based on the Trichodesmium physiology (the most studied nitrogen fixer) within a 3-D coupled dynamical–biogeochemical model (ROMS-PISCES). We performed a climatological numerical simulation that is able to reproduce the main physical (e.g. sea surface temperature) and biogeochemical patterns (nutrient and chlorophyll concentrations, as well as N2 fixation) in the tropical Pacific. This simulation displayed a Trichodesmium regional distribution that extends from 150∘ E to 120∘ W in the south tropical Pacific, and from 120∘ E to 140∘ W in the north tropical Pacific. The local simulated maximuma were found around islands (Hawaii, Fiji, Samoa, New Caledonia, Vanuatu). We assessed that 15 % of the total primary production may be due to Trichodesmium in the low-nutrient low-chlorophyll regions (LNLC) of the tropical Pacific. Comparison between our explicit and the often used (in biogeochemical models) implicit parameterization of N2 fixation showed that the latter leads to an underestimation of N2 fixation rates by about 25 % in LNLC regions. Finally, we established that iron fluxes from island sediments control the spatial distribution of Trichodesmium biomasses in the western tropical South Pacific. Note, this last result does not take into account the iron supply from rivers and hydrothermal sources, which may well be of importance in a region known for its strong precipitation rates and volcanic activity.
    Type of Medium: Online Resource
    ISSN: 1726-4189
    URL: Article
    URL: Article
    DOI: 10.5194/bg-15-4333-2018
    DOI: 10.5194/bg-15-4333-2018-supplement
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2018
    detail.hit.zdb_id: 2158181-2
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 4
    Online Resource
    Online Resource
    Heterotrophic bacterial production and metabolic balance during the VAHINE mesocosm experiment in the New Caledonia lagoon
    Copernicus GmbH ; 2016
    In:  Biogeosciences Vol. 13, No. 11 ( 2016-06-02), p. 3187-3202
    Details
    In: Biogeosciences, Copernicus GmbH, Vol. 13, No. 11 ( 2016-06-02), p. 3187-3202
    Abstract: Abstract. Studies investigating the fate of diazotrophs through the microbial food web are lacking, although N2 fixation can fuel up to 50 % of new production in some oligotrophic oceans. In particular, the role played by heterotrophic prokaryotes in this transfer is largely unknown. In the frame of the VAHINE (VAriability of vertical and tropHIc transfer of diazotroph derived N in the south wEst Pacific) experiment, three replicate large-volume (∼ 50 m3) mesocosms were deployed for 23 days in the new Caledonia lagoon and were intentionally fertilized on day 4 with dissolved inorganic phosphorus (DIP) to stimulate N2 fixation. We specifically examined relationships between heterotrophic bacterial production (BP) and N2 fixation or primary production, determined bacterial growth efficiency and established carbon budgets. BP was statistically higher during the second phase of the experiment (P2: days 15–23), when chlorophyll biomass started to increase compared to the first phase (P1: days 5–14). Phosphatase alkaline activity increased drastically during the second phase of the experiment, showing adaptations of microbial populations after utilization of the added DIP. Notably, among autotrophs, Synechococcus abundances increased during P2, possibly related to its capacity to assimilate leucine and to produce alkaline phosphatase. Bacterial growth efficiency based on the carbon budget (27–43 %), was notably higher than generally cited for oligotrophic environments and discussed in links with the presence of abundant species of bacteria expressing proteorhodopsin. The main fates of gross primary production (particulate + dissolved) were respiration (67 %) and export through sedimentation (17 %). BP was highly correlated with particulate primary production and chlorophyll biomass during both phases of the experiment but was slightly correlated, and only during P2 phase, with N2 fixation rates. Heterotrophic bacterial production was strongly stimulated after mineral N enrichment experiments, suggesting N-limitation of heterotrophic bacteria across the experiment. N2 fixation rates corresponded to 17–37 % of the nitrogen demand of heterotrophic bacteria. Our results suggest that most of the diazotroph-derived nitrogen fuelled the heterotrophic bacterial community through indirect processes generating dissolved organic matter and detritus, like mortality, lysis and grazing of both diazotrophs and non-diazotrophs.
    Type of Medium: Online Resource
    ISSN: 1726-4189
    URL: Article
    URL: Article
    DOI: 10.5194/bg-13-3187-2016
    DOI: 10.5194/bg-13-3187-2016-supplement
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2016
    detail.hit.zdb_id: 2158181-2
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 5
    Online Resource
    Online Resource
    Remote sensing of 〈i〉Trichodesmium〈/i〉 spp. mats in the western tropical South Pacific
    Copernicus GmbH ; 2018
    In:  Biogeosciences Vol. 15, No. 16 ( 2018-08-29), p. 5203-5219
    Details
    In: Biogeosciences, Copernicus GmbH, Vol. 15, No. 16 ( 2018-08-29), p. 5203-5219
    Abstract: Abstract. Trichodesmium is the major nitrogen-fixing species in the western tropical South Pacific (WTSP) region, a hot spot of diazotrophy. Due to the paucity of in situ observations, remote-sensing methods for detecting Trichodesmium presence on a large scale have been investigated to assess the regional-to-global impact of this organism on primary production and carbon cycling. A number of algorithms have been developed to identify Trichodesmium surface blooms from space, but determining with confidence their accuracy has been difficult, chiefly because of the scarcity of sea-truth information at the time of satellite overpass. Here, we use a series of new cruises as well as airborne surveys over the WTSP to evaluate their ability to detect Trichodesmium surface blooms in the satellite imagery. The evaluation, performed on MODIS data at 250 m and 1 km resolution acquired over the region, shows limitations due to spatial resolution, clouds, and atmospheric correction. A new satellite-based algorithm is designed to alleviate some of these limitations, by exploiting optimally spectral features in the atmospherically corrected reflectance at 531, 645, 678, 748, and 869 nm. This algorithm outperforms former ones near clouds, limiting false positive detection and allowing regional-scale automation. Compared with observations, 80 % of the detected mats are within a 2 km range, demonstrating the good statistical skill of the new algorithm. Application to MODIS imagery acquired during the February-March 2015 OUTPACE campaign reveals the presence of surface blooms northwest and east of New Caledonia and near 20∘ S–172∘ W in qualitative agreement with measured nitrogen fixation rates. Improving Trichodesmium detection requires measuring ocean color at higher spectral and spatial (〈250 m) resolution than MODIS, taking into account environment properties (e.g., wind, sea surface temperature), fluorescence, and spatial structure of filaments, and a better understanding of Trichodesmium dynamics, including aggregation processes to generate surface mats. Such sub-mesoscale aggregation processes for Trichodesmium are yet to be understood.
    Type of Medium: Online Resource
    ISSN: 1726-4189
    URL: Article
    DOI: 10.5194/bg-15-5203-2018
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2018
    detail.hit.zdb_id: 2158181-2
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 6
    Online Resource
    Online Resource
    Diazotrophic 〈i〉Trichodesmium〈/i〉 impact on UV–Vis radiance and pigment composition in the western tropical South Pacific
    Copernicus GmbH ; 2018
    In:  Biogeosciences Vol. 15, No. 16 ( 2018-08-30), p. 5249-5269
    Details
    In: Biogeosciences, Copernicus GmbH, Vol. 15, No. 16 ( 2018-08-30), p. 5249-5269
    Abstract: Abstract. We assessed the influence of the marine diazotrophic cyanobacterium Trichodesmium on the bio-optical properties of western tropical South Pacific (WTSP) waters (18–22∘ S, 160∘ E–160∘ W) during the February–March 2015 OUTPACE cruise. We performed measurements of backscattering and absorption coefficients, irradiance, and radiance in the euphotic zone with a Satlantic MicroPro free-fall profiler and took Underwater Vision Profiler 5 (UPV5) pictures for counting the largest Trichodesmium spp. colonies. Pigment concentrations were determined by fluorimetry and high-performance liquid chromatography and picoplankton abundance by flow cytometry. Trichome concentration was estimated from pigment algorithms and validated by surface visual counts. The abundance of large colonies counted by the UVP5 (maximum 7093 colonies m−3) was well correlated to the trichome concentrations (maximum 2093 trichomes L−1) with an aggregation factor of 600. In the Melanesian archipelago, a maximum of 4715 trichomes L−1 was enumerated in pump samples (3.2 m) at 20∘ S, 167 30∘ E. High Trichodesmium abundance was always associated with absorption peaks of mycosporine-like amino acids (330, 360 nm) and high particulate backscattering, but not with high Chl a fluorescence or blue particulate absorption (440 nm). Along the west-to-east transect, Trichodesmium together with Prochlorococcus represented the major part of total chlorophyll concentration; the contribution of other groups were relatively small or negligible. The Trichodesmium contribution to total chlorophyll concentration was the highest in the Melanesian archipelago around New Caledonia and Vanuatu (60 %), progressively decreased to the vicinity of the islands of Fiji (30 %), and reached a minimum in the South Pacific Gyre where Prochlorococcus dominated chlorophyll concentration. The contribution of Trichodesmium to zeaxanthin was respectively 50, 40 and 20 % for these regions. During the OUTPACE cruise, the relationship between normalized water-leaving radiance (nLw) in the ultraviolet and visible and chlorophyll concentration was similar to that found during the BIOSOPE cruise in the eastern tropical Pacific. Principal component analysis (PCA) of OUTPACE data showed that nLw at 305, 325, 340, 380, 412 and 440 nm was strongly correlated to chlorophyll and zeaxanthin, while nLw at 490 and 565 nm exhibited lower correlations. These results, as well as differences in the PCA of BIOSOPE data, indicated that nLw variability in the greenish blue and yellowish green during OUTPACE was influenced by other variables associated with Trichodesmium presence, such as backscattering coefficient, phycoerythrin fluorescence and/or zeaxanthin absorption, suggesting that Trichodesmium detection should involve examination of nLw in this spectral domain.
    Type of Medium: Online Resource
    ISSN: 1726-4189
    URL: Article
    DOI: 10.5194/bg-15-5249-2018
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2018
    detail.hit.zdb_id: 2158181-2
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 7
    Online Resource
    Online Resource
    Trophic position increases with thermocline depth in yellowfin and bigeye tuna across the Western and Central Pacific Ocean
    Elsevier BV ; 2017
    In:  Progress in Oceanography Vol. 154 ( 2017-05), p. 49-63
    Details
    In: Progress in Oceanography, Elsevier BV, Vol. 154 ( 2017-05), p. 49-63
    Type of Medium: Online Resource
    ISSN: 0079-6611
    URL: Article
    DOI: 10.1016/j.pocean.2017.04.008
    RVK:
    RB 10402
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2017
    detail.hit.zdb_id: 1497436-8
    detail.hit.zdb_id: 4062-9
    SSG: 21,3
    SSG: 14
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 8
    Online Resource
    Online Resource
    Plankton biomass and production in an open atoll lagoon: Uvea, New Caledonia
    Elsevier BV ; 1997
    In:  Journal of Experimental Marine Biology and Ecology Vol. 212, No. 2 ( 1997-5), p. 187-210
    Details
    In: Journal of Experimental Marine Biology and Ecology, Elsevier BV, Vol. 212, No. 2 ( 1997-5), p. 187-210
    Type of Medium: Online Resource
    ISSN: 0022-0981
    URL: Article
    DOI: 10.1016/S0022-0981(96)02749-9
    Language: English
    Publisher: Elsevier BV
    Publication Date: 1997
    detail.hit.zdb_id: 410283-6
    detail.hit.zdb_id: 1483103-X
    SSG: 12
    SSG: 7,20
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 9
    Online Resource
    Online Resource
    Temporal variability in dissolved inorganic nitrogen fluxes at the sediment–water interface and related annual budget on a continental shelf (NW Mediterranean)
    Elsevier BV ; 2001
    In:  Oceanologica Acta Vol. 24, No. 1 ( 2001-1), p. 85-97
    Details
    In: Oceanologica Acta, Elsevier BV, Vol. 24, No. 1 ( 2001-1), p. 85-97
    Type of Medium: Online Resource
    ISSN: 0399-1784
    URL: Article
    DOI: 10.1016/S0399-1784(00)01130-0
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2001
    detail.hit.zdb_id: 2044478-3
    detail.hit.zdb_id: 435214-2
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 10
    Online Resource
    Online Resource
    Zonal variability of plankton and particle export flux in the equatorial Pacific upwelling between 165° E and 150° W
    Elsevier BV ; 1999
    In:  Oceanologica Acta Vol. 22, No. 1 ( 1999-1), p. 57-66
    Details
    In: Oceanologica Acta, Elsevier BV, Vol. 22, No. 1 ( 1999-1), p. 57-66
    Type of Medium: Online Resource
    ISSN: 0399-1784
    URL: Article
    DOI: 10.1016/S0399-1784(99)80033-4
    Language: English
    Publisher: Elsevier BV
    Publication Date: 1999
    detail.hit.zdb_id: 2044478-3
    detail.hit.zdb_id: 435214-2
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...