Distribution of 222RN on the Continental Shelf in Southern Brazil and its Relation with Groundwater Discharge

This study examines surficial sediment distribution patterns, slope and morphological characteristics of the Parana inner continental shelf. Parana inner continental shelf is located on the southern Brazilian continental shelf, a wide and low gradient shelf, in the vicinity of two large unfilled estuaries and the Serra do Mar mountain range. It is characterized as a wave/storm dominated continental shelf with microtidal, semidiurnal regime and a small supply of recent continental sediments. We analyzed grain-size parameters and sediment composition of 875 grab samples and investigated the inner continental shelf morphology and slope through a digital bathymetric model built from regional nautical charts. We combined and evaluated the characteristics of grain-size curves, the spatial distribution of sediments, and the morphology and slope of the inner continental shelf to identify different sedimentary facies. Sediment distribution patterns change from the coast seaward and between three defined sectors along the coastline: south, central and north inner continental shelf. This variation seems to be related to recent sediment sources and to the presence of deposits from ancient coastal plain and inner continental shelf environments formed before the last Holocene sea-level highstand. Sediments with mean diameter of fine to very fine sands prevail at all depths. Deposits of sediments with mean diameter of silt and medium to coarse sands are significant in particular areas, generally associated with steep slopes, troughs, and sand ridges. Possible causes of sedimentary patchiness are the outcropping of medium to coarse sand and the supply of recent estuarine muddy sediments provided by large estuarine complexes to the Parana inner continental shelf. The results obtained contribute to the knowledge about the sediment dynamics of Parana inner continental shelf.

Data from ichthyoplankton surveys between 1980 and 1990 are used to describe the distribution of bluefish (Pomatomus saltatrix) larvae along the continental shelf off southern Brazil (24�-35�S). Only 46 larvae in 9 stations were found in 1026 oblique and horizontal tows taken with a 330 pm-mesh Bongo net. Larvae ranged in size from 3 to 10 mm, with the larger larvae distributed close to shore. There were no significant differences in size between larvae found in the northern and southern regions of the shelf. However, there was evidence of a gradual northward displacement of larval abundance towards winter. About 85% of the larvae occurred in the southernmost region of the shelf (below 32�S) in January and February (summer), and the remaining larvae were caught further north from March to August. This pattern of larval distribution could be attributed to the northwards retreat of warmer (> 20�C) and more saline (> 34) Brazilian coastal waters from the region. Results from this study suggest that bluefish spawn over a protracted period, following the seasonal displacement of Brazilian coastal waters along the continental shelf off southern Brazil, a pattern that is also consistent with the spawning migration proposed for bluefish in the north-western Atlantic.

Here are described post mortem modifications (pseudopaleopathologies) in 762 specimens of extinct mammals from three middle to late Pleistocene assemblages (Campanha, Chui Creek and continental shelf) of the state of Rio Grande do Sul, southern Brazil. These assemblages include mostly large-sized herbivores preserved in fluvial facies, although the assemblage from the shelf consist of remains that were reworked several times by sea-level oscillations. Although some patterns of modification are similar between the assemblages (e.g. post-fossilization plain fractures), others such as the grade of abrasion or weathering varies according to the depositional setting. The scarcity of modifications that could be attributed to predators or scavengers indicate that carnivory was not a major process driving the formation of the assemblages. Most of the fossils from the Campanha are complete, but a relatively high proportion of them exhibits advanced stage of weathering, whereas those from Chui Creek and the continental shelf are mostly unweathered. Most of the remains from the Campanha and Chui Creek are unabraded, whereas all fossils from the shelf were subject to abrasion. Few fossils exhibit signs of modification by organisms such as plants and insects. Fossils from the continental shelf have crusts of beach rock, and some specimens from the Campanha and Chui Creek have crusts of calcium carbonate or iron oxide. Besides the abrasion, the main difference between fossils from the continental and marine assemblages is the dark color and higher mechanical resistance of the latter. This difference is related to post depositional geochemical processes in the marine environment. The chemical composition of fossils from Chui Creek and continental shelf was qualitatively analyzed using energy dispersive X-ray spectrometry (EDX) and compared with recent bones. The results show the presence in the fossils of several elements not found in recent bones, incorporated through diagenetic processes controlled by specific conditions of each depositional environment.

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 300:229-240 (2005) - doi:10.3354/meps300229 Distribution and habitat characteristics of dolphins of the genus Stenella (Cetacea: Delphinidae) in the southwest Atlantic Ocean Ignacio B. Moreno1,2,7,*, Alexandre N. Zerbini3, Daniel Danilewicz1,2, Marcos C. de Oliveira Santos4, Paulo C. Simões-Lopes5, Jose Lailson-Brito Jr.6, Alexandre F. Azevedo6 1Grupo de Estudos de Mamíferos Aquáticos do Rio Grande do Sul (GEMARS), Rua Felipe Neri 382/203, Porto Alegre, Rio Grande do Sul 90440-150, Brazil2Centro de Estudos Costeiros, Limnológicos e Marinhos (CECLIMAR) & Universidade Federal do Rio Grande do Sul (UFRGS), Avenida Tramandaí 976, Imbé, Rio Grande do Sul 95625-000, Brazil3Washington Cooperative Fish and Wildlife Research Unit, School of Aquatic and Fishery Sciences, Box 355020, University of Washington, Seattle, Washington 98195-5020, USA4Projeto Atlantis—Departamento de Ecologia Geral, Instituto de Biociências—USP, Rua do Matão 321, Cidade Universitária, São Paulo, São Paulo 05508-900, Brazil5Laboratório de Mamíferos Aquáticos, Departamento de Ecologia e Zoologia, Universidade Federal de Santa Catarina, Caixa Postal 5102, Florianópolis, Santa Catarina 88040-970, Brazil6Laboratório de Mamíferos Aquáticos (MAQUA)/UERJ, Rua São Francisco Xavier 524/4018E, Rio de Janeiro,Rio de Janeiro 20550-013, Brazil7Present address: Pós-Graduação em Biociências, Laboratório de Ictiologia, Museu de Ciências e Tecnologia/PUCRS, Avenida Ipiranga 6681, Caixa Postal 1429, Porto Alegre, Rio Grande do Sul 90619-900, Brazil *Email: iggy.moreno@gmail.com ABSTRACT: The distribution of dolphins of the genus Stenella is poorly known in the southwest Atlantic Ocean. A complete review of records (n = 311) of these dolphin species was performed to describe distribution and habitat. Atlantic spotted dolphins S. frontalis occur in both southern (21 to 33°S) and northern Brazil (north of 06°S), with a hiatus in its distribution off eastern South America. This species presents the highest preference for nearshore habitats, restricted to waters within the 1000 m isobath. Pantropical spotted dolphins S. attenuata are found in tropical waters as far south as 22°S and are mainly observed off northeastern South America. They occur beyond the continental shelf break in depths >850 m. Clymene dolphins S. clymene are distributed in deep waters (1390 to 4500 m) as far south as 30°S. Strandings are more common where the continental shelf is narrower. Spinner dolphins S. longirostris are found in oceanic waters as far south as 30°S. They inhabit tropical waters over the shelf and slope (depths ranging from 170 to 2700 m). The striped dolphin S. coeruleoalba is the least known species of the genus in the western South Atlantic. Most records are from temperate waters in southern Brazil and Argentina. The distributions of S. attenuata, S. clymene and S. longirostris overlap to a great extent and are predominantly oceanic and associated with warm ocean currents. S. frontalis seems to prefer a different, coastal habitat, influenced both by warm currents and upwelling areas. The discontinuous distribution of this species suggests that an isolated population inhabits the southern coast of Brazil. KEY WORDS: Stenella · Atlantic Ocean · Brazil · Uruguay · Argentina · Distribution · Habitat characteristics Full text in pdf format Supplemental Appendix PreviousExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 300. Online publication date: September 16, 2005 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2005 Inter-Research.

Geomorphological and stratigraphic evolution of a fluvial incision in the coastal plain and inner continental shelf in southern Brazil

Beachrocks are a common feature along the Brazilian coast and although their occurrence in intertidal zones is concentrated in tropical regions, similar formations have been described submerged on the continental shelf in subtropical regions. In the state of Parana, submerged sandstones are present on the continental shelf and their formation could be associated with the cementation of beach sediments. This would provide an excellent indicator of the stabilization of the coastline during lower sea-level periods. In this study, samples were identified and collected in Parana State, Southern Brazil, at depths between 18 and 33 meters in the continental shelf and at 6 meters depth in the Paranagua Bay inlet. As in situ observations proved problematic, analysis relied mainly on their petrography, mineralogy, ages and isotopic values (δ13C and δ18O). Whole rock dating demonstrated that the oldest acquired sample was formed 28109-26406 cal. years BP, being exposed to atmospheric conditions during the Last Glacial Maximum. This exposure is reflected in its cements, composed uniquely of microcrystalline and spar calcite, and on its δ18O/δ13C values, which indicates formation on a fresh water environment. Contrarily to most carbonate cemented products described along Brazilian coastline, δ13C values ranged between -26.36 and -51.07‰ on all other samples, interpreted as a result of cement precipitation prompted by methane, either: in a paleo-estuarine/ paleo-lagunar to transgressive environment buried under a pile of coarser material or; after transgression and drowning of organic-rich sediments by coarser sediments, and due to upward migration of methane on the sedimentary column. Both processes would result in cements identified on these samples, apart from the one collected closer to shore which indicates some freshwater influence. Two of the samples separated by 15km distance perpendicularly to the actual coastline and 11m depth difference yielded max and minimum ages of 7913 and 7452 cal. years BP. Such a short time span between these samples could be either the result of their formation on a linked environment or older carbon signature from drowned environments being present on younger cements.

Local hydrography and interactions with benthic megafauna explain fish assemblage structure on the shallow inner shelf of Paraná, southern Brazil

Research Article| April 01, 1970 Shallow Structure of the Continental Margin, Southern Brazil and Uruguay LOUIS W BUTLER LOUIS W BUTLER ESSA Atlantic Oceanographic and Meteorological Laboratories, Miami, Florida 33130 Search for other works by this author on: GSW Google Scholar GSA Bulletin (1970) 81 (4): 1079–1096. https://doi.org/10.1130/0016-7606(1970)81[1079:SSOTCM]2.0.CO;2 Article history received: 04 Aug 1969 rev-recd: 05 Nov 1969 first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation LOUIS W BUTLER; Shallow Structure of the Continental Margin, Southern Brazil and Uruguay. GSA Bulletin 1970;; 81 (4): 1079–1096. doi: https://doi.org/10.1130/0016-7606(1970)81[1079:SSOTCM]2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract The shallow structure of two coastal basins or embayments along the continental margin of southern Brazil and Uruguay was investigated by geophysical techniques during a cruise of the U.S. Coast and Geodetic Survey Ship Oceanographer in late 1966.Deformation of the continental shelf and slope sediments in the first of these basins, the São Paulo Embayment, situated between Rio de Janeiro and Florianópolis, suggests the presence of diapiric intrusions. Grabens developed above diapirs are reflected as topographic valleys on the continental slope and as zones of contemporaneous faulting on the outer shelf where sedimentation has kept pace with deformation. The São Paulo Embayment subsided sufficiently from Late Cretaceous through Pleistocene time to accommodate a series of three prograded sedimentary wedges with a cumulative stratigraphic thickness of at least 4 km. Each wedge of prograded sediment is presumed correlative with the onset of block-faulting, uplift, and rejuvenation of a mountain complex which borders the landward edge of the São Paulo Embayment. The axis of maximum sediment accumulation has migrated landward during the Tertiary.In any reconstruction of pre-rift South America and Africa, the São Paulo Embayment lies immediately to the south of the Cuanza Basin of Angola. These two coastal basins have Mesozoic similarities but, beginning in the Tertiary, their patterns of marine sedimentation diverge; this fact is consistent with proposed Cretaceous rifting of this portion of the two continents.The Pelotas Basin may be traced from beneath the coastal lagoons in southern Brazil and Uruguay part-way across the continental shelf. The continental slope off the Pelotas Basin consists of a large conical apron of sediment; the deeper strata are arched mildly and younger sediments thin over structural highs. The relationship of the cone to the Pelotas Basin is not clear.Although submarine canyons are numerous and well-developed north and south of the study area, only fault-controlled valleys are known along the southern Brazil margin. Outcrops of continental shelf strata are rare along the slope; progradation and slope-conformable sedimentation are the rule. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

This systematic study of the polychaete species of the family Glyceridae is part of a broader program to inventory and determine parameters for conservation and sustainable use of the marine biodiversity off the southeastern and southern coast of Brazil. The material studied was collected from intertidal sandy beaches, the inner continental shelf (<50 m depth) off the northern coast of the state of São Paulo, and the outer continental shelf and part of the continental slope (depths from 60 to 808 m) off the state of Rio de Janeiro south to Rio Grande do Sul (22° S - 34° 40' S). The descriptions of several species were improved, adding new and important taxonomic characters, mainly related to proboscideal papillae. A key for identification of the glycerid species from southeastern and southern Brazil is also provided. Eight species of Glyceridae were identified: Glycera americana Leidy 1855; Glycera brevicirris Grube 1870; Glycera dibranchiata Ehlers 1868; Glycera lapidum Quatrefages 1866; Glycera oxycephala Ehlers 1887; Glycera tesselata Grube 1863; Hemipodia californiensis (Hartman 1938); Hemipodia simplex (Grube 1857); and a previously unknown species of Glycera.

Patos Lagoon outflow within the Río de la Plata plume using an airborne salinity mapper: Observing an embedded plume

Squalus megalops and Squalus mitsukurii are recognized as the most abundant Squalus species in the southern Brazil region. Currently, S. megalops is listed as ‘least concern’ (LC) and S. mitsukurii as ‘endangered’ (EN). However, at the regional level, both species are classified as ‘data deficient’ – DD, due to the lack of population local data. In this context, the present study aimed to determine the reproductive biology parameters of these species. In addition, insights on their abundance were provided. Research cruises using bottom trawls were conducted on the continental shelf off southern Brazil between 2001 and 2002. A total of 298 specimens of S. megalops (♂143|♀156) and 297 specimens of S. mitsukurii (♂129|♀166) were captured. For S. megalops, the L50 was 38.2 cm for males and 50.22 cm for females, with ovarian fecundity ranging from 1 to 4 vitellogenic follicles and uterine fecundity from 1 to 4 embryos. S. mitsukurii presented an L50 of 54.12 cm for males and 66.4 cm for females, with ovarian fecundity ranging from 1 to 8 vitellogenic follicles and uterine fecundity ranging from 1 to 8 embryos. The highest catch per unit of effort (CPUE) for S. megalops was in zone B (2360.43 ind/mn2) and for S. mitsukurii in zone A (5287.97 ind/mn2). The study observed differences in the reproductive stages and fecundity of both species compared to other studies for the same species. In southern Brazil, the calculated L50 sizes were smaller than those obtained in the northeast, potentially due to higher fishing pressure. Obtaining data on poorly known species reinforces the importance of monitoring fisheries in the region. The maturity data presented are crucial for species classified as DD, such as S. megalops and S. mitsukurii in southern Brazil, potentially generating new information to support local fisheries management.

Food and feeding of the short-finned squid Illex argentinus (Cephalopoda: Ommastrephidae) off southern Brazil

The geological evolution of the continental shelf and in the coastal zone of southern Brazil during the Quaternary period is addressed in this study. High-resolution seismic records obtained at the Patos Lagoon revealed the presence of channels that deeply dissected the coastal zone before the formation of the modern, low-relief, coastal plain. Two periods of channel incision are inferred, based mainly on seismic records. The paleodrainage paths mapped from the seismic records can be connected with those recognized by previous studies on the adjacent continental shelf and slope. Upstream, the drainage incised mainly into the coastal prism deposited during previous sea-level highstand events. The paleodrainage network, recognized on the coastal plain and continental shelf, represents a river-shelf system, linking the drainage basin to the depositional settings on the marginal basin, bypassing the continental shelf exposed during a forced regression event. The drainage incised into the coastal plain and continental shelf of Rio Grande do Sul played an important role in the basin-margin architecture, facies distribution and accommodation during the Quaternary sea-level fluctuations.

Tracing anthropogenically driven groundwater discharge into a coastal lagoon from southern Brazil

Phytoplankton community structure in relation to hydrographic features along a coast-to-offshore transect on the SW Atlantic Continental Shelf