Gaube P.,Woods Hole Oceanographic Institution |
Gaube P.,University of Washington |
Barcelo C.,Oregon State University |
McGillicuddy D.J.,Woods Hole Oceanographic Institution |
And 5 more authors.
PLoS ONE | Year: 2017
Marine animals, such as turtles, seabirds and pelagic fishes, are observed to travel and congregate around eddies in the open ocean. Mesoscale eddies, large swirling ocean vortices with radius scales of approximately 50-100 km, provide environmental variability that can structure these populations. In this study, we investigate the use of mesoscale eddies by 24 individual juvenile loggerhead sea turtles (Caretta caretta) in the Brazil-Malvinas Confluence region. The influence of eddies on turtles is assessed by collocating the turtle trajectories to the tracks of mesoscale eddies identified in maps of sea level anomaly. Juvenile loggerhead sea turtles are significantly more likely to be located in the interiors of anticyclones in this region. The distribution of surface drifters in eddy interiors reveals no significant association with the interiors of cyclones or anticyclones, suggesting higher prevalence of turtles in anticyclones is a result of their behavior. In the southern portion of the Brazil-Malvinas Confluence region, turtle swimming speed is significantly slower in the interiors of anticyclones, when compared to the periphery, suggesting that these turtles are possibly feeding on prey items associated with anomalously low near-surface chlorophyll concentrations observed in those features. © This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.
Pimpao D.M.,Instituto Brasileiro do Meio Ambiente e dos Recursos Naturais Renovaveis IBAMA |
Veitenheimer-Mendes I.L.,Centro Universitario La Salle |
Scarabino F.,Direccion Nacional de Recursos Acuaticos
Check List | Year: 2010
An analysis of bivalves shells collected off the coast of Rio Grande, Rio Grande do Sul, Brazil and specimens of scientific collections, identified as Cuspidaria braziliensis E. A. Smith, 1915 was made. From the examination of syntypes of C. braziliensis and the type species of the genus Plectodon Carpenter, 1864, a redescription was made and it is proposed to transfer the species to the genus Plectodon, resulting in the new combination Plectodon braziliensis (E.A. Smith, 1915). This is the first record of a Plectodon species for the South Atlantic. © 2010 Check List and Authors.
Oddone M.C.,Grande Rio University |
Paesch L.,Direccion Nacional de Recursos Acuaticos |
Norbis W.,Institute Biologia
Journal of Northwest Atlantic Fishery Science | Year: 2010
A total of 1 893 males and 1 124 females of Squalus mitsukurii were collected from latitudes 34o 30' S and 37o 00' S, in the south-western Atlantic Ocean, during early autumn, late autumn and spring 1995, early autumn 1996 and early autumn 1998. Length-frequency distributions significantly varied between sexes for all seasons (P<0.05). Mature males predominated in all seasons throughout the analyzed area, according to their presence in the catches. In all periods sampled, immature females predominated except for late autumn 1995 where mature females were dominant. Significant differences in density among seasons were recorded for immature and mature females and mature males (P<0.05). Density of immature females and mature males were significantly different (P<0.05) for late autumn 1995 and early autumn 1996. Size-at-maturity was 43.1 cm and 55.9 cm total length for males (n = 1 181) and females (n = 862) receptively. The percentage of pregnant females ranged from 21.4% in spring 1995 to 49.8% in late autumn 1995. Ovarian fecundity varied significantly between early autumn 1995 and late autumn 1995 from 1-15 and uterine fecundity from 1-10, respectively. Embryo total length varied from 0.5-22.0 cm, attaining the highest values in autumn months. Sizeat- birth was estimated to be 22-24 cm total length.
de Mello C.,Direccion Nacional de Recursos Acuaticos |
Gonzalez S.,Direccion Nacional de Recursos Acuaticos |
Scarabino F.,Direccion Nacional de Recursos Acuaticos
Biological Invasions | Year: 2010
We report on the first sightings of the invasive Rapa Whelk Rapana venosa in Maldonado Bay (Punta del Este Harbor and Gorriti Island) using in vivo, underwater observations and video surveys. The species was first detected in the Río de la Plata (Uruguay and Argentina) in 1999, and by 2004 it had extended its local distribution to Punta del Este at the eastern boundary of the estuary. Observations performed by SCUBA diving showed that R. venosa is preying on native mussels Mytilus edulis and Brachidontes spp., and that formerly abundant mussel beds are being seriously depleted due to a combination of human extraction, habitat deterioration and predation by the Rapa Whelk. © Springer Science+Business Media B.V. 2009.
Jimenez S.,Proyecto Albatros y Petreles Uruguay |
Jimenez S.,University of the Republic of Uruguay |
Abreu M.,Proyecto Albatros y Petreles Uruguay |
Pons M.,Direccion Nacional de Recursos Acuaticos |
And 3 more authors.
Aquatic Living Resources | Year: 2010
The black-browed (Thalassarche melanophrys) and Atlantic yellow-nosed (Thalassarche chlororhynchos) albatrosses and the white-chinned petrel (Procellaria aequinoctialis) are the seabird species most frequently captured by pelagic longline fisheries in the southwest Atlantic. This study estimates this type of bycatch and describes the spatial-temporal patterns of the incidental capture of these species by the Uruguayan pelagic longline fleet, based on data collected by scientific observers on 47 fishing trips from 2004 to 2007. Three generalized linear models (GLM) models were employed to predict bycatch for each species based on the observed data. We also developed a spatio-temporal species-specific analysis. Captures were recorded in Uruguayan waters, mainly over the slope and depth waters, and in international waters adjacent to Uruguay, the north of Argentina, and the south of Brazil. The highest catch rates for black-browed albatrosses and white-chinned petrels were recorded on the Uruguayan slope from fall to spring, while the highest values for Atlantic yellow-nosed albatrosses were recorded further to the north, in the international waters off Brazil in late winter. The average estimated number of black-browed and Atlantic yellow-nosed albatrosses and white-chinned petrels caught during the study period was 1683, 257 and 239 birds, respectively. Taking into account the total effort of the fleet, these values represent an estimated catch rate of 0.276, 0.042, and 0.039 birds/1000 hooks for these species, respectively. The results of the present study suggest that the annual impact of this fishery is medium to high on the black-browed albatross, low on the Atlantic yellow-nosed albatross and low on the white-chinned petrel. However, the situation of these species in the southwest Atlantic should be viewed with considerable concern, as our understanding of the impact of the bycatch on their populations requires more research. Any effort to reduce seabird mortality in the southern hemisphere should target this geographic region. © 2010 EDP Sciences, IFREMER, IRD.
Franco-Fraguas P.,University of the Republic of Uruguay |
Burone L.,University of the Republic of Uruguay |
Mahiques M.,University of Sao Paulo |
Ortega L.,Direccion Nacional de Recursos Acuaticos |
Carranza A.,University of the Republic of Uruguay
Marine Geology | Year: 2016
Recent high-resolution, multidisciplinary studies have provided models of modern and ancient sedimentary processes along the Uruguayan slope (34°S to 36°S), a strategic location in the Southwestern Atlantic margin (SAM). According to these models, modern surface sedimentation is controlled by the transition between the Subtropical Shelf Front and the Brazil-Malvinas Confluence (BMC), and presumably by the summer Rio de la Plata (RdlP) buoyant plume. Ancient sedimentary dynamics is reflected as the northernmost distribution of the contouritic terraces present in the Argentinean margin, reflecting the position of the BMC during glacial stages. In this work, the spatial correlation of previous evidence from modern (surface facies) and ancient (geomorphological features) sedimentation provides a sound framework in order to interpret novel information on the geochemical composition of surface sediments. Proxies for the origins of lithogenic (Nd, Al/Si, and Fe/K) and organic matter (C/N, δ13C, and δ15N), previously calibrated for the SAM, and the elemental compositions (Al, TI, Fe, K, Mn, Ca, P, Mg, Ba, and Si) of surface sediments were used to test working hypotheses on sediment provenance, surface productivity and the environmental control of elementary composition. The distribution of surface sediments is correlated with regional geomorphology, which includes contouritic terraces in the south and a progradational slope in the north. This supports the idea of a strong morphological control on the modern sedimentary processes. However, the distribution and content of terrigenous, biogenic and erosional elements, together with the dominance of Pampean Patagonian sediments, suggests that 1) the RdlP does not contribute with any lithogenic sediments to the slope and, instead, fertilizes open waters with contributions consisting of mixed marine organic matter; 2) in the north, the strong action of the BC and the re-circulated AAIW below promotes redistribution of sediments from the shelf and upper slope towards the middle slope, including sandy spillover/slump transport and hemipelagic sedimentation re-suspended from the continental shelf; 3) with respect to glacial stages, this across-slope sedimentation was displaced southwards dominating even the northernmost distribution of contouritic terraces and 4) sedimentation related to contouritic features, as modern depositional and erosional sedimentation, was restricted to the south accompanying the distribution of the MC. Thus, although the core hypothesis of the previous modern sedimentary model can be retained, considerable improvements in our knowledge of the sediment dynamics in the SAM have emerged from the present analysis of geochemical proxies. © 2016 Elsevier B.V.
Alonso C.,Institute Investigaciones Biologicas Clemente Estable |
Gomez-Pereira P.,Max Planck Institute for Marine Microbiology |
Ramette A.,Max Planck Institute for Marine Microbiology |
Ortega L.,Direccion Nacional de Recursos Acuaticos |
And 2 more authors.
Aquatic Microbial Ecology | Year: 2010
The Río de la Plata is the world's largest estuary, draining the second largest basin of South America. In spite of its key significance at the local and global scale, this is the first attempt made so far to characterize the bacterial diversity of this system. We employed a suite of molecular methods to analyze the bacterial diversity at different phylogenetic levels, both in terms of richness and evenness, and we related these findings to physicochemical parameters. A clear environmental gradient was observed with 3 distinctive zones (riverine, frontal, and marine). In turn, the bacterial communities appeared highly diverse and strongly structured by the environment. A high number (324) of different operational taxonomic units (OTUs) were identified by automated ribosomal intergenic spacer analysis (ARISA). The ARISA results suggested that the composition of bacterioplankton communities was strongly related to physicochemical water characteristics, and that the bacterioplankton had little overlap with the bacterial assemblage of the sediments. Catalyzed reporter deposition-fluorescence in situ hybridization (CARD-FISH) indicated that Betaproteobacteria and Actinobacteria were more abundant in the riverine zone, whereas Gammaproteobacteria and Planctomycetes preferred the marine waters. The relative abundance of Bacteroidetes peaked in the frontal zone, and Alphaproteobacteria were numerically dominant throughout the estuary. The analysis of about 300 almost full-length 16S rRNA gene sequences pointed to the existence of ubiquitous phylotypes, but also suggested habitat preferences among certain groups. This first look into the bacterial community of the Río de la Plata demonstrated marked diversity patterns, providing further insights into the ecology of globally distributed groups of aquatic bacteria. © Inter-Research 2010.
Sophia M.D.G.,Federal University of Rio de Janeiro |
Perez M.D.C.,Direccion Nacional de Recursos Acuaticos
Iheringia - Serie Botanica | Year: 2010
Merin Lagoon is a large, shallow and subtropical water body shared by the countries Uruguay and Brazil. The desmids composition of Merin Lagoon was analyzed at seven sites in March, July-August, November 1998 and January 1999, based on plankton net samples. The temperature and conductivity of the water presented the lowest values (15°C and 70 μS.cm-1) in July-August 1998 and highest (25°C and 105 μS.cm-1) in January 1999, the pH values varied from neutral to slightly alkaline, between 6.5 and 8.7. A total of 61 desmids taxa belonging to 15 genera were identified and Staurastrum Meyen ex Ralfs (19), Cosmarium Corda ex Ralfs (10), Closterium Nitzsch ex Ralfs (6), and Staurodesmus Teiling (6) were the greatest represented genera. The most frequent taxon was Staurastrum leptocladum Nordstedt var. smithii Grönblad. The high desmid richness in Merin Lagoon and the lack of information about this algal group in this lagoon justify the present study.
Pereyra S.,University of the Republic of Uruguay |
Garcia G.,University of the Republic of Uruguay |
Miller P.,Direccion Nacional de Recursos Acuaticos |
Miller P.,Research Center y Conservacion Marina |
And 2 more authors.
Fisheries Research | Year: 2010
The narrownose smooth-hound shark Mustelus schmitti is a coastal species endemic to the Southwest Atlantic Ocean. As this species is an important fishery resource, there is interest in knowing its genetic population structure. In this study, we used mitochondrial cytochrome b gene sequences to examine the genetic structure of the narrownose smooth-hound populations within the Río de la Plata and its Maritime Front in the SW Atlantic Ocean. We found no evidence for genetic structure in the analyzed samples. Low levels of pairwise ΦST values indicated high connectivity and suggested genetic homogeneity at this geographic range. Additionally, notably low nucleotide and haplotype diversities found in this species could indicate that M. schmitti experienced a population bottleneck, recent expansion or selection. The results presented here indicate that M. schmitti exists as a single demographic unit in the Río de la Plata and its Maritime Front. The low genetic diversity values found in the present study, together with the low resilience to exploitation of this species, raise considerable concern over the conservation status of M. schmitti. © 2010 Elsevier B.V.
Galli O.,Direccion Nacional de Recursos Acuaticos |
Norbis W.,Direccion Nacional de Recursos Acuaticos |
Norbis W.,University of the Republic of Uruguay
Journal of Applied Ichthyology | Year: 2013
Summary: The aim of this work was to compare the morphometric and meristic characteristics of whitemouth croaker, Micropogonias furnieri, from two different areas: the Río de la Plata (to the west) and the oceanic coast (to the east) during the summer spawning season (December 1999), and to determine whether they constitute one demographic unit or independent management groups. Data from 966 whitemouth croakers were analysed for stock discrimination between areas. The results provided further evidence that the two cohorts differ significantly in these areas. However, an important misclassification of individuals was found. The morphometric variables that contributed more to discriminate the groups were mouth length, head length, horizontal eye diameter and length of the pectoral fin. Misclassified individuals from the western and eastern groups have shown that whitemouth croaker do not display high fidelity to their known spawning grounds. The well-classified and misclassified individuals for the western and eastern groups were found to be mature and in spawning condition, representing between 82-84%, and 66-88%, respectively. These results support the hypothesis of contemporary gene flow between the Río de la Plata and coastal Atlantic populations. Despite the misclassified individuals, morphometrics presented in this study and genetic information originating from other studies show differences between Río de la Plata and oceanic groups, and predict the two-stock hypothesis. Problems related arising from these mixed population groups and potential implications for managements are discussed. © 2013 Blackwell Verlag GmbH.