Recent Benthic Foraminifers from the South Atlantic Shelf of Argentina

2018 ◽  
Vol 48 (3) ◽  
pp. 210-222 ◽  
Author(s):  
Emiliana Bernasconi ◽  
Mario Mansilla ◽  
Gabriela Cusminsky
Keyword(s):  
Continental Shelf ◽  
Physicochemical Parameters ◽  
Multivariate Analyses ◽  
Temperature Zone ◽  
Free Living ◽  
Benthic Foraminifers ◽  
Zone Ii ◽  
Recent Sediments ◽  
Sandy Sediments ◽  
Saline Zone

Abstract The aim of this study was to determine foraminiferal associations from recent sediments of Argentina's continental shelf (39–41ºS, 59–61ºW; 11–70 m) and assess their relationship to physicochemical parameters. From 20 samples, all dominated by sandy sediments (>80% sand), 44 species of foraminifers were identified, most commonly Buccella peruviana. Recovered foraminiferal tests were generally well preserved, with morphologies indicating predominantly epifaunal, free-living detritivores from well-oxygenated waters. Multivariate analyses showed a strong correlation between foraminiferal assemblages and four zones related to physicochemical parameters. Zone I included the offshore samples from depths of 40–70 m where waters were slightly colder and more saline. Zone II samples were all collected from depths of 30–40 m that were intermediate in temperature. Zone III occurred at 20–40 m depth where sediments were characterized by some gravel content. Zone IV included the inshore sites (<20 m) offshore from the Rio Colorado delta. This work contributes to the knowledge of foraminifers on Argentina's continental shelf, complementing earlier studies of foraminiferal distributions and ecology from the region.

Ecological study based on the distribution of recent foraminifers from southeast of Buenos Aires province, Argentinean Continental Shelf

Zootaxa ◽  
2020 ◽  
Vol 4821 (1) ◽  
pp. 135-147
Author(s):  
EMILIANA BERNASCONI
Keyword(s):  
Buenos Aires ◽  
High Energy ◽  
Buenos Aires Province ◽  
Inner Shelf ◽  
Foraminiferal Assemblage ◽  
Benthic Foraminifers ◽  
Oxygen Levels ◽  
Trophic Strategy ◽  
Local Water ◽  
Sandy Sediments

The study about the distribution of benthic foraminifers in relationship with the type of substrate is presented. Samples of surface sediments from 15 to 60 m of depth from the southeast coast of the province of Buenos Aires (40º 30´ - 42ºS), Argentina were analysed. The foraminiferal assemblage was constituted by forty-eight species that belong to 22 genera. It was characterized mostly by the free-living style, epifaunal microhabitats, oxic levels and a detritivore trophic strategy. Based on statistical analysis, three zones were determinated: at 15 m depth , characterized mainly by Buccella peruviana (d´Orbigny), and species of Bolivina reflected a littoral environment with sandy sediments and the most important clay contribution, whereas it also presented the lowest oxygen levels were determinated; between 24-48 m depth, associted by Ammonia parkinsoniana (d´Orbigny), Buccella peruviana and Quinqueloculina seminula (Linné), this zone displayed an oxygenated environment with coarse grainsize from inner shelf where local water circulation may explain the high energy observed; and the last one located between 36 to 58 m of depth was characterized by Buccella peruviana, Ammonia parkinsoniana, Elphidium macellum (Fichtel & Moll), Cibicides dispars (d´Orbigny) and Cibicides aknerianus (d´Orbigny) regflecting an inner shelf environment with sandy sediments, the lowest water temperature and the highest oxygen levels.

Composition and spatio-temporal variation in the density of the Brachyura (Decapoda, Pleocyemata) in the rocky substrates of an Amazonian estuary

Crustaceana ◽  
2016 ◽  
Vol 89 (13) ◽  
pp. 1447-1466 ◽  
Author(s):  
Priscila S. V. Nóbrega ◽  
Jussara M. Martinelli-Lemos
Keyword(s):  
Species Richness ◽  
Species Composition ◽  
Rainy Season ◽  
Multivariate Analyses ◽  
Temporal Distribution ◽  
Homogeneous Distribution ◽  
Influence Of Temperature ◽  
Spatio Temporal ◽  
Outer Estuary ◽  
Saline Zone

The present study investigated the composition, spatio-temporal distribution, and the influence of temperature and salinity on the density of brachyurans associated with rocky substrates in an estuary of the Brazilian Amazonian coast. Specimens were collected monthly at four sites representing the two margins (profiles), zones (inner and outer estuary) and the lower and upper mediolittoral portions at each site of the Marapanim estuary. A total of 14 species were collected and multivariate analyses revealed that the species composition varied systematically between zones, margins, mediolittoral sectors and seasons, with the more saline zone, the most eroded margin, the lower mediolittoral, and the rainy season all being characterized by higher densities and a more homogeneous distribution of species. In general, high densities of brachyurans, but low species richness, and marked dominance characterized the sites. Salinity proved to play an important role in the structuring of the community.

scholarly journals Spatio-temporal variability of amphipod assemblages associated with rhodolith seabeds

2021 ◽  
Vol 72 (1) ◽  
pp. 76 ◽  
Author(s):  
Sandra Navarro-Mayoral ◽  
Victoria Fernandez-Gonzalez ◽  
Francisco Otero-Ferrer ◽  
Fernando Tuya
Keyword(s):  
Population Structure ◽  
Temporal Variability ◽  
Multivariate Analyses ◽  
Assemblage Structure ◽  
Free Living ◽  
Gran Canaria ◽  
Four Seasons ◽  
Spatio Temporal ◽  
Diversity Structure ◽  
Ecological Pattern

Rhodolith seabeds are habitats underpinned by free-living calcareous macroalgae. We partitioned the relevance of the scale of temporal (four seasons throughout two successive years) and spatial (three depth strata: 18, 25 and 40m) variation on the diversity, structure and abundance of amphipod assemblages living in rhodolith seabeds from Gran Canaria Island. In total, 3996 individuals, belonging to 32 taxa, were identified. Multivariate analyses showed consistent differences in assemblage structure among seasons and depths; more diverse and abundant amphipod assemblages were often observed during spring at 18- and 25-m than at 40-m depth. Ovigerous females of Gammaropsis ostroumowi and Ampithoe ramondi were observed mainly at 18 and 25m. Juveniles of both species were exclusively recorded at 18 and 25m, so denoting a clear segregation in their population structure with depth. In summary, this study has demonstrated that the ecological pattern of amphipods associated with rhodolith seabeds can vary greatly across both time (seasons) and space (depth).

scholarly journals Taxonomy of Middle Miocene foraminifera from the northern Namibian continental shelf

Zootaxa ◽  
2022 ◽  
Vol 5091 (1) ◽  
pp. 1-55
Author(s):  
EUGENE W. BERGH ◽  
JOHN S. COMPTON
Keyword(s):  
Continental Shelf ◽  
Middle Miocene ◽  
Regional Distribution ◽  
Outer Continental Shelf ◽  
Benthic Species ◽  
Planktic Foraminifera ◽  
Benguela Upwelling ◽  
Orbulina Universa ◽  
Recent Sediments ◽  
First Time

Middle Miocene foraminifera from the northern Namibian outer continental shelf are indicators of a period prior to the initiation of the Benguela Upwelling System (BUS). This study provides an update to the occurrence and taxonomy of Miocene foraminifera from the continental margin of Namibia. The taxonomy of 51 benthic and 12 planktic foraminiferal species from the northern Namibian shelf are discussed, their stratigraphic significance given, and their ecological preferences and regional distribution summarised within this study. The identification of extinct planktic foraminifera provided key stratigraphic control for the middle Miocene strata of this region. The taxa identified in this study provide a distinct and different assemblage to the overlying younger strata. Many of the species recorded in this study have not been identified in the region and are reported for the first time from the middle Miocene on the southwestern continental shelf of Africa, off Namibia. A total of 47 species are identified and discussed for the first time from this region. Nineteen species recorded in this study are extinct and eleven taxa reported here have previously only been reported on the genus level on the southwestern shelf of South Africa. Seven benthic species (Amphicoryna scalaris, Marginulina obesa, Glandulina laevigata, Globocassidulina subglobosa, Uvigerina peregrina, Sphaeroidina bulloides and Melonis affinis) and two planktic species (Globigerina bulloides and Orbulina universa) did not disappear from the regional stratigraphy and continued to occur in Plio-Pleistocene to Recent sediments along the southwestern continental shelf of Africa.  

Distribution and Characteristics of Sandy Sediments along the Northeastern Continental Shelf of Korea in the East Sea

2020 ◽  
Vol 95 (sp1) ◽  
pp. 532
Author(s):  
So-Ra Kim ◽  
Jong-Hwa Chun ◽  
In-Kwon Um ◽  
Deniz Cukur
Keyword(s):  
Continental Shelf ◽  
East Sea ◽  
Sandy Sediments

Recent benthic foraminifers of the Basque continental shelf (Bay of Biscay, northern Spain): Oceanographic implications

2013 ◽  
Vol 66 ◽  
pp. 105-122 ◽  
Author(s):  
Blanca Martínez-García ◽  
Ana Pascual ◽  
Julio Rodríguez-Lázaro ◽  
Arantxa Bodego
Keyword(s):  
Continental Shelf ◽  
Bay Of Biscay ◽  
Northern Spain ◽  
Benthic Foraminifers

Four new species of free-living nematodes from shallow continental shelf of Portugal

Zootaxa ◽  
2020 ◽  
Vol 4722 (1) ◽  
pp. 1-33
Author(s):  
TACIANA KRAMER PINTO ◽  
PATRICIA FERNANDES NERES
Keyword(s):  
Continental Shelf ◽  
Buccal Cavity ◽  
Marine Biodiversity ◽  
Main Character ◽  
Marine Nematodes ◽  
Cavity Size ◽  
Free Living ◽  
System Project ◽  
Amphidial Fovea ◽  
Biodiversity Information

Free-living marine nematodes of continental shelf of Portugal were studied through the goals of the Marine Biodiversity Information System Project (M@rbis 2015). Four species unknown to science and belonging to the families Axonolaimidae, Chromadoridae, Desmodoridae and Xyalidae are described. Besides Hypodontolaimus golikovy, Hypodontolaimus portuguese sp. n. is the only species in this genus which lacks precloacal supplements and gubernaculum but differs from the former mainly in cephalic setae length and amphidial fovea features. Metachromadora aliusa sp. n. doesn’t have a unique diagnostic character, differing in many aspects from the other species of the genus instead, mainly teeth number in the buccal cavity, size of the cephalic setae and the amphidial fovea, velum presence in the spicules, number and shape of the precloacal supplements. The main character of Odontophora sinapophysis sp. n. is the absence of apophysis in the gubernaculum. Stylotheristus multipapillatus sp. n. is characterized by the presence of precloacal supplements (papilliform) and the gubernaculum formed by only a piece. 

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