scholarly journals Nitrogen-fixing populations of Planctomycetes and Proteobacteria are abundant in the surface ocean

2017 ◽  
Author(s):  
Tom O. Delmont ◽  
Christopher Quince ◽  
Alon Shaiber ◽  
Özcan C. Esen ◽  
Sonny TM Lee ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Primary Productivity ◽  
Global Climate ◽  
Available Nitrogen ◽  
Widespread Occurrence ◽  
Surface Ocean ◽  
The Pacific ◽  
Reductase Gene ◽  
The Pacific Ocean ◽  
First Time

AbstractNitrogen fixation in the surface ocean impacts the global climate by regulating the microbial primary productivity and the sequestration of carbon through the biological pump. Cyanobacterial populations have long been thought to represent the main suppliers of the bio-available nitrogen in this habitat. However, recent molecular surveys of nitrogenase reductase gene revealed the existence of rare non-cyanobacterial populations that can also fix nitrogen. Here, we characterize for the first time the genomic content of some of these heterotrophic bacterial diazotrophs (HBDs) inhabiting the open surface ocean waters. They represent new lineages within Planctomycetes and Proteobacteria, a phylum never linked to nitrogen fixation prior to this study. HBDs were surprisingly abundant in the Pacific Ocean and the Atlantic Ocean northwest, conflicting with decades of PCR surveys. The abundance and widespread occurrence of non-cyanobacterial diazotrophs in the surface ocean emphasizes the need to re-evaluate their role in the nitrogen cycle and primary productivity.

scholarly journals Biogeochemistry of the North Atlantic during oceanic anoxic event 2: role of changes in ocean circulation and phosphorus input

2014 ◽  
Vol 11 (4) ◽  
pp. 977-993 ◽  
Author(s):  
I. Ruvalcaba Baroni ◽  
R. P. M. Topper ◽  
N. A. G. M. van Helmond ◽  
H. Brinkhuis ◽  
C. P. Slomp
Keyword(s):  
Pacific Ocean ◽  
Ocean Circulation ◽  
North Atlantic ◽  
Primary Productivity ◽  
Low Oxygen ◽  
Deep Basin ◽  
The North ◽  
The Pacific ◽  
The Pacific Ocean ◽  
The North Atlantic

Abstract. The geological record provides evidence for the periodic occurrence of water column anoxia and formation of organic-rich deposits in the North Atlantic Ocean during the mid-Cretaceous (hereafter called the proto-North Atlantic). Both changes in primary productivity and oceanic circulation likely played a role in the development of the low-oxygen conditions. Several studies suggest that an increased input of phosphorus from land initiated oceanic anoxic events (OAEs). Other proposed mechanisms invoke a vigorous upwelling system and an ocean circulation pattern that acted as a trap for nutrients from the Pacific Ocean. Here, we use a detailed biogeochemical box model for the proto-North Atlantic to analyse under what conditions anoxia could have developed during OAE2 (94 Ma). The model explicitly describes the coupled water, carbon, oxygen and phosphorus cycles for the deep basin and continental shelves. In our simulations, we assume the vigorous water circulation from a recent regional ocean model study. Our model results for pre-OAE2 and OAE2 conditions are compared to sediment records of organic carbon and proxies for photic zone euxinia and bottom water redox conditions (e.g. isorenieratane, carbon/phosphorus ratios). Our results show that a strongly elevated input of phosphorus from rivers and the Pacific Ocean relative to pre-OAE2 conditions is a requirement for the widespread development of low oxygen in the proto-North Atlantic during OAE2. Moreover, anoxia in the proto-North Atlantic is shown to be greatly influenced by the oxygen concentration of Pacific bottom waters. In our model, primary productivity increased significantly upon the transition from pre-OAE2 to OAE2 conditions. Our model captures the regional trends in anoxia as deduced from observations, with euxinia spreading to the northern and eastern shelves but with the most intense euxinia occurring along the southern coast. However, anoxia in the central deep basin is difficult to achieve in the model. This suggests that the ocean circulation used in the model may be too vigorous and/or that anoxia in the proto-North Atlantic was less widespread than previously thought.

scholarly journals Species Composition and New Records of Diatom Taxa on Phyllodictyon pulcherrimum (Chlorophyceae) from the Gulf of California

Diversity ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 339
Author(s):  
Francisco Omar López-Fuerte ◽  
David Alfaro Siqueiros Beltrones ◽  
María del Carmen Altamirano-Cerecedo
Keyword(s):  
Gulf Of California ◽  
New Records ◽  
American Continent ◽  
Epiphytic Diatoms ◽  
Taxonomic Analysis ◽  
The North ◽  
The Pacific ◽  
The Pacific Ocean ◽  
First Time ◽  
The North Pacific

A taxonomic analysis of diatoms found on Phyllodictyon pulcherrimum yielded a total of 244 diatom taxa (all illustrated) within 27 orders, 45 families, and 86 genera. The Taxa were briefly documented in a list including identification references and morphometric data. Thirty-eight of the taxa identified at the species and infraspecific levels represent new records for the coasts of Mexico. Seven were recorded for the first time on the American continent: Auricula flabelliformis, A. pulchra, Campylodiscus scalaris, Coscinodiscus mesoleius, Dimeregramma fulvum, Navicula palpebralis var. angulosa, and Seminavis barbarae, and one, Nitzschia fusiformis, for the Pacific Ocean. This is the second record of the chlorophyte P. pulcherrimum in the north Pacific and the third for Mexican waters. The results confirm that surveying rare macroalgae species as hosts for epiphytic diatoms provides opportunities to seek new records of diatom taxa, or even new taxa, in regions around the world.

IODP Expedition 378 South Pacific Paleogene Climate: New high-resolution high-latitude Cenozoic Section

2020 ◽  
Author(s):  
Ursula Röhl ◽  
Deborah J Thomas ◽  
Laurel Childress ◽  
Keyword(s):  
Pacific Ocean ◽  
High Latitude ◽  
Global Climate ◽  
South Pacific ◽  
The South ◽  
Red Clay ◽  
South Pacific Ocean ◽  
The Pacific ◽  
The Pacific Ocean ◽  
International Ocean Discovery Program

<p>As the world’s largest ocean, the Pacific Ocean is intricately linked to major changes in the global climate system. International Ocean Discovery Program (IODP) Expedition 378 is designed to recover Paleogene sedimentary sections in the South Pacific to reconstruct key changes in oceanic and atmospheric circulation. These cores will provide an unparalleled opportunity to add crucial new data and geographic coverage to existing reconstructions of Paleogene climate and as part of a major regional slate of expeditions in the Southern Ocean to fill a critical need for high-latitude climate reconstructions. Appropriate high-latitude records are unobtainable in the Northern Hemisphere of the Pacific Ocean.</p><p>The drilling strategy included a transect of sites strategically positioned in the South Pacific to recover Paleogene carbonates buried under red clay sequences at present latitudes of 40°–52°S in 4650 – 5075 meters of water depth. Due to technical issues we no longer will be able to reach the deeper sites. Therefore, the focus of Expedition 378 will be now to obtain a continuous sedimentary record of a previously single hole, rotary-drilled, spot-cored, classic Cenozoic high-latitude DSDP Site 277 and provide a crucial, multiple hole, mostly APC-cored, continuous record of the intermediate-depth Subantarctic South Pacific Ocean from the Latest Cretaceous to late Oligocene.</p>

A new species ofTriptolemma(Porifera: Pachastrellidae) from the Pacific Ocean with a revision of the genus

2010 ◽  
Vol 91 (2) ◽  
pp. 329-338 ◽  
Author(s):  
Marco Bertolino ◽  
D. Pica ◽  
G. Bavestrello ◽  
N. Iwasaki ◽  
B. Calcinai
Keyword(s):  
New Species ◽  
Pacific Ocean ◽  
Chemical Dissolution ◽  
Typical Pattern ◽  
Etching Mechanism ◽  
The Pacific ◽  
The Pacific Ocean ◽  
First Time ◽  
A New Species ◽  
Thick Crust

A new species,T. strongylatasp. nov. is described on the basis of material collected from the Pacific Ocean. The new species is characterized by the presence of sinuous strongyles. Moreover the incomplete description ofT. simplex(Sarà, 1959) is implemented on the basis of new abundant material allowing, for the first time, the complete description of the skeleton of aTriptolemmaspecies and the detecting of the presence of monaxonic spicules in the spicular complement of the genus. The skeleton is composed of a thick crust of disorderly arranged mesotriaenes and scattered microscleres, supported by diverging spicule tracts formed by oxeas towards the surface. Both species were recorded associated to boring sponges(SpiroxyaandCliona)in excavations of the calcareous scleraxis of precious corals or in organogenic concretions. In the cavities where the tissue ofTriptolemmawas recorded the wall of the excavation partially lost its typical pattern characterized by ovoid scars and became irregularly eroded. Our hypothesis is thatTriptolemmainsinuates inside the erosions produced by other sponges and it is able to enlarge them by an etching mechanism based on chemical dissolution only.

RECORDS OF CYAMUS BALAENOPTERAE BARNARD AND NEOCYAMUS PHYSETERIS (POUCHET), TWO SPECIES OF WHALE-LICE (AMPHIPODA), FROM THE NORTHEAST PACIFIC

1959 ◽  
Vol 37 (6) ◽  
pp. 895-897 ◽  
Author(s):  
L. Margolis
Keyword(s):  
Pacific Ocean ◽  
First Record ◽  
Physeter Macrocephalus ◽  
Balaenoptera Acutorostrata ◽  
Northeast Pacific ◽  
The Pacific ◽  
The Pacific Ocean ◽  
First Time

Cyamus balaenopterae Barnard from Balaenoptera acutorostrata and Neocyamus physeteris (Pouchet) from Physeter macrocephalus are reported for the first time from the Pacific Ocean. This is the first record of a cyamid from B. acutorostrata.

Explorers' and Travelers' Narratives: A Peregrination Through Different Editions

2003 ◽  
Vol 30 ◽  
pp. 213-222 ◽  
Author(s):  
I.S. MacLaren
Keyword(s):  
Native People ◽  
James Cook ◽  
The Third ◽  
The Pacific ◽  
The Press ◽  
Field Notes ◽  
The Pacific Ocean ◽  
First Editions ◽  
First Time ◽  
George Iii

Researchers keen to examine the representation of native people in European accounts of exploration and travel need bring under review the mechanism by which field notes became books, and, once they were books, the multiplicity and diffusion of editions, often themselves quite different from one another. An example that illustrates well this need is British Royal Naval Captain James Cook's posthumously published account of his third voyage to the Pacific Ocean in the years 1776-80. The standard scholarly source is J.C. Beaglehole's monumental edition, The Journals of Captain James Cook on His Voyages of Discovery (1955-74), a twenty-year editing project for the Hakluyt Society, which made available for the first time Cook's own writings until his death at Kealakekua Bay, Sandwich Islands (Hawaii), on 14 February 1779, during the third voyage. However, the need for Beaglehole's project arose, according to the president of the Hakluyt Society, because the original publications differed very widely from Cook's own writings. They were “official” accounts, published by order of George III, and they performed that always interesting exercise—they “improved” on Cook's own writings. It is well known that Cook did not prepare his journals for the press: in the case of the first two voyages to the Pacific, this was his choice. In the case of the third, the choice was not his to make, he being five years deceased. How wide are those differences?In the case of Cook's description of a month-long mooring in Nootka Sound, on the west coast of Vancouver Island, do substantive differences occur between Cook's logs and journal and Bishop John Douglas' edition? Answering that question necessarily involves consulting first editions of the various published accounts.

scholarly journals Two continents and two names for a Neotropical colletid bee species (Hymenoptera: Colletidae: Neopasiphaeinae): Hoplocolletes ventralis (Friese, 1924)

2015 ◽  
Author(s):  
Eduardo A B Almeida ◽  
Fábio B Quinteiro
Keyword(s):  
Pacific Ocean ◽  
South America ◽  
Comparative Study ◽  
Neotropical Species ◽  
The Pacific ◽  
The Pacific Ocean ◽  
Phylogenetic Hypotheses ◽  
First Time

Neopasiphaeinae bees (Apoidea: Colletidae) are well known for their Amphinotic distribution in the Australian and Neotropical regions. Affinities between colletid taxa in Australia and South America have been speculated for decades, and have been confirmed by recent phylogenetic hypotheses that indicate a biogeographic scenario compatible with a trans-Antarctic biotic connection during the Paleogene. Despite this proximity, no species occurs on both sides of the Pacific Ocean, but the Neotropical species Hoplocolletes ventralis (Friese, 1924), which was described as an Australian taxon due to an error in the specimen labels. This mistake was recognized by C.D.Michener 50 years ago. We herein report that the same labeling problem also happened with Dasycolletes chalceus Friese, 1924, which remained as a tentatively placed species in the Australian genus Leioproctus until now. Moreover, Dasycolletes chalceus is interpreted as a synonym of Dasycolletes ventralis. We also provide a revised diagnosis for Hoplocolletes, describe the male of H. ventralis in detail for the first time, including a comparative study of its genitalia and associated sterna.

scholarly journals Proteorhodopsins dominate the expression of phototrophic mechanisms in seasonal and dynamic marine picoplankton communities

2018 ◽  
Author(s):  
Ella T Sieradzki ◽  
Jed A Fuhrman ◽  
Sara Rivero-Calle ◽  
Laura Gómez-Consarnau
Keyword(s):  
Marker Gene ◽  
Single Copy ◽  
Oxygenic Photosynthesis ◽  
Sampling Location ◽  
Pr Genes ◽  
Surface Ocean ◽  
San Pedro ◽  
Accessory Function ◽  
The Pacific ◽  
The Pacific Ocean

The most abundant and ubiquitous microbes in the surface ocean use light as an energy source, capturing it via complex chlorophyll-based photosystems or simple retinal-based rhodopsins. Studies in various ocean regimes compared the abundance of these mechanisms, but few investigated their expression. Here we present the first full seasonal study of abundance and expression of light-harvesting mechanisms (proteorhodopsin, PR; aerobic anoxygenic photosynthesis, AAnP; and oxygenic photosynthesis, PSI) from deep-sequenced metagenomes and metatranscriptomes of marine picoplankton (< 1 µm) at three coastal stations of the San Pedro Channel in the Pacific Ocean. We show that, regardless of season or sampling location, the most common phototrophic mechanism in metagenomes of this dynamic region was PR (present in 65-104% of the genomes as estimated by single-copy recA), followed by PSI (5-104%) and AAnP (5-32%). Furthermore, the normalized expression (RNA to DNA ratio) of PR genes was higher than that of oxygenic photosynthesis (average±standard deviation 26.2±8.4 vs. 11±9.7), and the expression of the AAnP marker gene was significantly lower than both mechanisms (0.013±0.02). We demonstrate that rhodopsin expression was dominated by the SAR11-cluster year-round, followed by other Alphaproteobacteria, unknown-environmental clusters and Gammaproteobacteria. This highly dynamic system further allowed us to identify a trend for PR spectral tuning, in which blue-absorbing PR genes dominate in areas with low chlorophyll-aconcentrations (< 0.25 µg/L). This suggests that PR phototrophy is not an accessory function but instead a central mechanism that can regulate photoheterotrophic population dynamics.

scholarly journals Shallow architecture of Fuegian Andes lineaments based on Electrical Resistivity Tomography (ERT). Evidences of transverse extensional faulting in the central Beagle Channel area

2017 ◽  
Vol 45 (1) ◽  
pp. 1 ◽  
Author(s):  
Donaldo Mauricio Bran ◽  
Alejandro Alberto Tassone ◽  
Marco Menichetti ◽  
María Elena Cerredo ◽  
Jorge Gabriel Lozano ◽  
...  
Keyword(s):  
Fault System ◽  
Resistivity Tomography ◽  
Widespread Occurrence ◽  
Beagle Channel ◽  
Field Evidence ◽  
The Pacific ◽  
Vertical Displacements ◽  
The Pacific Ocean ◽  
Extensional Faulting ◽  
Northern Shore

The southern foothills of the Fuegian Andes are bounded by the Beagle Channel (BC), a conspicuous E-W longitudinal basin, controlled by a large transcurrent fault system, which extends from the Atlantic to the Pacific Ocean. The northern shore of the Beagle Channel’s central segment is characterized by several E-W oriented valleys, parallel to the main basin, which are interspersed with a series of oblique NW trending lineaments that extend across the mountain belt. A geoelectrical survey was carried out in order to investigate the shallow architecture of such sets of linear morphologies. The principal E-W lineament system was characterized by conspicuous sub-vertical resistivity contrasts, interpreted as fractured zones associated with fault strands of the main strike-slip Beagle Channel system, whereas the oblique NW-SE trending set of lineaments revealed slightly different resistivity patterns, with vertical displacements and less abrupt contrasts. These resistivity patterns, in combination with the widespread occurrence of normal faulting in the area, allowed to infer an extensional control over the oblique depressions. These morphological features were related to oblique transverse faults that segment two sub parallel E-W fault systems. The oblique faults were probably developed along inherited structural anisotropies and can be extended well beyond the BC shoreline to the NW. Both geophysical and field evidence suggest a post-glacial deformation along the area.

scholarly journals Dissolution of cobalt and zinc from natural and anthropogenic dusts in seawater

2010 ◽  
Vol 7 (6) ◽  
pp. 1927-1936 ◽  
Author(s):  
C.-E. Thuróczy ◽  
M. Boye ◽  
R. Losno
Keyword(s):  
Mixed Layer ◽  
Flow Reactor ◽  
Anthropogenic Sources ◽  
Anthropogenic Aerosol ◽  
Surface Ocean ◽  
Anthropogenic Inputs ◽  
The Pacific ◽  
The Pacific Ocean ◽  
Voltammetric Methods

Abstract. Atmospheric dust inputs to the surface ocean are a major source of trace metals likely to be bio-available for phytoplankton after their dissolution in seawater. Among them, cobalt (Co) and zinc (Zn) are essential for phytoplankton growth and for the distribution of the major groups such as coccolithophorids, cyanobacteria and diatoms. The solubility in seawater of Co and Zn present in natural and anthropogenic dusts was studied using an open-flow reactor with and without light irradiation. Those dusts can be transported in the atmosphere by the wind before being deposited to the surface ocean. The analyses of cobalt and zinc were conducted using voltammetric methods and the global elemental composition of dust was determined by ICP-AES. This study highlighted the role of the dust origin in revealing the solubility characteristics. Much higher dust solubility was found for zinc as compared to cobalt; cobalt in anthropogenic particles was much more soluble (0.78%) in seawater after 2 h of dissolution than Co in natural particles (0.14%). Zinc showed opposite solubility, higher in natural particles (16%) than in anthropogenic particles (5.2%). A natural dust event to the surface ocean could account for up to 5% of the cobalt inventory and up to 50% of the Zn inventory in the mixed layer in the Pacific Ocean whereas the cobalt and zinc inventories in the mixed layer of the Atlantic Ocean might already include the effects of natural dust inputs and the subsequent metal dissolution. Anthropogenic sources to the surface ocean could be as important as the natural sources, but a better estimate of the flux of anthropogenic aerosol to the surface ocean is needed to further estimate the anthropogenic inputs. Variations in natural and anthropogenic inputs may induce large shifts in the Co/Zn ratio in the surface ocean; hence it could impact the phytoplankton community structure.

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