A synthesis of the sedimentary evolution of the Demerara Plateau (Central Atlantic Ocean) from the late Albian to the Holocene

Phytolith and macroscopic charcoal in cumulative soils on the Soni Plateau, Central Japan, were evaluated to clarify the Holocene history of intentional fires and grassland development, and to compare the findings with those derived from pollen and charcoal records in sediments taken from a nearby mire in the previous study. Prior to ~1500 cal. BP, Bambusoid short-cell phytoliths and Pleioblastus-type and Bambusoideae-type bulliform cell phytoliths were abundant with scarce charcoal particles (<1000 particles/cm3). In contrast, since ~1500 cal. BP Andropogoneae-type bulliform cell phytoliths and Bilobate short-cell phytoliths were dominant with abundant charcoal particles (>1000 particles/cm3). Based on correlating these records with pollen and charcoal records in mire sediments, prior to ~1500 cal. BP, dwarf bamboo flourished on the forest floor under largely fire-free conditions, whereas since ~1500 cal. BP, grassland dominated by Japanese pampas grass has been sustained by periodic intentional burning that has continued until the present day.

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From the Sea to the Land: Dynamic of the Sargassum Tide Holobiont in the Caribbean Islands

10.21203/rs.3.rs-33861/v1 ◽

2020 ◽

Author(s):

Pascal Jean Lopez ◽

Vincent Hervé ◽

Josie Lambourdière ◽

Malika René-Trouillefou ◽

Damien Devault

Keyword(s):

Atlantic Ocean ◽

Trophic Interactions ◽

Methanogenic Archaea ◽

Caribbean Region ◽

Brown Tides ◽

The Caribbean ◽

Risks Assessment ◽

Specific Species ◽

Associated Species ◽

Central Atlantic

Abstract BackgroundOver the last decade, intensity and frequency of Sargassum blooms in the Caribbean Sea and central Atlantic Ocean have dramatically increased, causing growing ecological, social and economic concern throughout the entire Caribbean region. These golden-brown tides form an ecosystem that maintains life for a large number of associated species, and their circulation across the Atlantic Ocean support the displacement and maybe the settlement of various species, especially microorganisms. To comprehensively identify the micro- and meiofauna associated to Sargassum, one hundred samples were collected during the 2018 tide events that were the largest ever recorded.ResultsWe investigated the composition and the existence of specific species in three compartments, namely, Sargassum at tide sites, in the surrounding seawater, and in inland seaweed storage sites. Metabarcoding data revealed shifts between compartments in both prokaryotic and eukaryotic communities, and large differences for eukaryotes especially bryozoans, nematodes and ciliates. Among the most abundant nematodes, we identified various bacterivores in all compartments, suggesting trophic interactions in Sargassum tides. We also found a number of species of interest, including methanogenic archaea, sulfate- and nitrate-reducing bacteria as well as putative pathogens.ConclusionsHere we present novel information on the diversity and trophic interactions of the micro- and meiofauna that are associated with Sargassum at tide and storage sites. Such information may help to better understand the ecological consequences of the Sargassum crises, and to develop proper analyses of the Sargassum associated biodiversity that could be important for application purposes such as biogas or fertilizers production, and to local authority for risks assessment.

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Seismic stratigraphy of Cretaceous eastern Central Atlantic Ocean: Basin evolution and palaeoceanographic implications

Earth and Planetary Science Letters ◽

10.1016/j.epsl.2018.07.023 ◽

2018 ◽

Vol 499 ◽

pp. 107-121 ◽

Cited By ~ 2

Author(s):

Yannick Mourlot ◽

Gérôme Calvès ◽

Peter D. Clift ◽

Guillaume Baby ◽

Anne-Claire Chaboureau ◽

...

Keyword(s):

Atlantic Ocean ◽

Seismic Stratigraphy ◽

Ocean Basin ◽

Basin Evolution ◽

Central Atlantic

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AGE AND GROWTH OF THE BLUE SHARK PRIONACE GLAUCA IN THE EASTERN ATLANTIC OCEAN

KSTU News ◽

10.46845/1997-3071-2021-62-11-25 ◽

2021 ◽

pp. 11-25

Author(s):

Beraki Weldegiorgish Teklekhaimanot ◽

Sergey Vadimovich Shibaev ◽

Sergey Yurievich Gulyugin

Keyword(s):

Atlantic Ocean ◽

Growth Parameters ◽

Growth Function ◽

Age And Growth ◽

Growth Band ◽

Prionace Glauca ◽

Western Africa ◽

Eastern Atlantic Ocean ◽

Digital Microscope ◽

Central Atlantic

In this study, 292 blue sharks Prionace glauca (Linnaeus, 1758) (from 151 to 305 cm total length, TL) were collected off western Africa in the eastern central Atlantic Ocean between 1980 and 1982. Vertebral sections of females specimens ranged from 175 to 300 cm and males specimens ranged from 166 to 312 cm TL were processed and analyzed for age and growth parameters. Growth band pairs (translucent and opaque bands) were counted on the images photographed from the stained whole vertebrae using digital microscope called Digi Scope II. The band pairs after the birthmark were counted from 3 to 12 for males and from 4 to 13 for females. Growth parameters were derived using the Von Bertalanffy growth function (VBGF) based on FISAT and solver solution Microsoft excel and Ford Wall-Ford. VBGF was that which best fit the data. Parameters derived from the combination of observed and back-calculated lengths, K = 0.1, L_∞ = 386.4 cm and t_0 = −1.35 year for males and K = 0.12 year -1, L_∞= 355 cm and t_0 = –1.02 year for females were considered to best describe growth. The longevity was estimated to be at least 23.7 and 28.3 years for females and males respectively. The natural mortality rate was estimated to be 0.15 year - 1 and 0.18 year -1 for males and females respectively.

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Concept of Biogenic Ferromanganese Crust Formation: Coccoliths as Bio-seeds in Crusts from Central Atlantic Ocean (Senghor Seamount/Cape Verde)

Natural Product Communications ◽

10.1177/1934578x1100600522 ◽

2011 ◽

Vol 6 (5) ◽

pp. 1934578X1100600

Author(s):

Xiaohong Wang ◽

Florian Peine ◽

Alexander Schmidt ◽

Heinz C. Schröder ◽

Matthias Wiens ◽

...

Keyword(s):

Atlantic Ocean ◽

Focused Ion Beam ◽

Ion Beam ◽

Deposition Process ◽

Ferromanganese Crust ◽

Cape Verde ◽

Surface Zone ◽

Ferromanganese Crusts ◽

Central Atlantic ◽

Scanning Electron

At depths of 2,000 to 3,000 m, seamounts from the Cape Verde archipelago (Central Atlantic Ocean) are largely covered with ferromanganese crusts. Here we studied 60 to 150 mm thick crusts from the Senghor Seamount (depth: 2257.4 m). The crusts have a non lamellated texture and are covered with spherical nodules. The chemical composition shows a dominance of MnO2 (26.1%) and Fe2O3 (38.8%) with considerable amounts of Co (0.74%) and TiO2 (2.1%). Analysis by scanning electron probe microanalyzer (EPMA) revealed a well defined compositional zonation of micro-layers; the distribution pattern of Mn does not match that of Fe. Analysis by high resolution scanning electron microscopy (SEM) revealed that coccospheres/coccoliths exist in the crust material as microfossils; most of the coccospheres/coccoliths are not intact. The almost circular coccoliths belong to the type of heterococcoliths and are taxonomically related to species of the family Calcidiscaceae. By energy dispersive X-ray spectroscopic analysis an accumulation of the coccoliths in the Mn- and Fe rich micronodules was detected. Focused ion beam assisted SEM mapping highlighted that the coccoliths in the crust are Mn rich, suggesting that the calcareous material of the algal skeleton has been replaced by Mn-minerals. We conclude that a biologically induced mechanism has been involved in the formation of the crusts, collected from the Cape Verde archipelago from depths of 2,000 to 3,000 m in the mixing region between the oxygen-minimum surface zone and the oxygen-rich deep waters; the deposition process might have been triggered by chemical reactions during the dissolution of the Ca-carbonate skeletons of the coccoliths allowing Mn(II) to oxidize to Mn(IV) and in turn to deposit this element in the crust material.

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On a collection of caridean shrimps (Decapoda, Caridea) from St. Helena, south-central Atlantic, with further records from Ascension Island

Crustaceana ◽

10.1163/15685403-00003909 ◽

2019 ◽

Vol 92 (7) ◽

pp. 869-879

Author(s):

Sammy De Grave ◽

Judith Brown ◽

Peter Wirtz ◽

Arthur Anker

Keyword(s):

Atlantic Ocean ◽

Endemic Species ◽

The South ◽

Number Of Species ◽

South Central ◽

Ascension Island ◽

Recent Collection ◽

St Helena ◽

Central Atlantic

Abstract We report on a recent collection of caridean shrimps from St. Helena in the south-central Atlantic Ocean, raising the total number of species known from the island to 24. Six species are newly recorded for the area, with no endemic species present. Additional three species are recorded from Ascension Island. A close biogeographical connection between the caridean faunas of St. Helena and Ascension Island is evident.

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