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Southwestern Atlantic (southwestern + atlantic)
Selected AbstractsEffects of Submerged Aquatic Vegetation on Macrozoobenthos in a Coastal Lagoon of the Southwestern AtlanticINTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 1 2007Rafael Arocena Abstract The freshwater-dominated part of Rocha coastal lagoon recently experienced sudden colonization by submerged aquatic vegetation (SAV). Macrophytes may be beneficial or detrimental for the zoobenthos, and both assemblages may in turn affect the food availability for birds and fishes. With the aim of evaluating the effect of SAV on water conditions and on the composition, abundance and diversity of macrozoobenthos, vegetated areas (V, up to 500 g DW m,2) were compared with vegetation-free areas (N). The benthic abundance was higher in V (up to 5000 ind m,2) than in N (up to 2200 ind m,2). Species richness and abundance of amphipods, gastropods and chironomids were also higher at V compared with N. Conversely, the abundance of Tanais stanfordi (Crustacea), Erodona mactroides (Bivalvia) and Laeonereis culveri (Polychaeta), and the Shannon diversity were higher at N. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Spatial correspondence between areas of concentration of Patagonian scallop (Zygochlamys patagonica) and frontal systems in the southwestern AtlanticFISHERIES OCEANOGRAPHY, Issue 5 2005EUGENIA BOGAZZI Abstract It has been hypothesized that the geographical location of scallop beds in extensive shelf regions mirrors hydrographic structures (e.g. frontal systems) that favor the retention/concentration of pelagic larvae. Large, discontinuous concentrations of the Patagonian scallop (Zygochlamys patagonica) are known to have occurred recurrently (for more than 30 yr) at certain geographical locations over the extensive Patagonian shelf. These stocks, exploited since 1996, currently support one of the most important scallop fisheries in the world. Here, we investigate whether those aggregations are spatially coincidental with major frontal systems. Several pieces of information were used: historical survey data documenting the geographic distribution of the Patagonian scallop beds, catch and effort data from the commercial fleet, oceanographic data on frontal systems, and remote sensing imagery. We found that large-scale aggregations do match the location of three major and very different frontal systems in the southwestern Atlantic: the Shelf-Break Frontal System, the Northern Patagonia Frontal System, and the Southern Patagonia Frontal System. We describe the three frontal systems and their associated scallops fishing grounds and discuss which processes can contribute to sustaining the productivity of the scallop grounds in each case. [source] Size at maturity and egg capsules of the softnose skates Bathyraja brachyurops (Fowler, 1910) and Bathyraja macloviana (Norman, 1937) (Elasmobranchii: Rajidae) in the SW Atlantic (37°00,,39°30,S)JOURNAL OF APPLIED ICHTHYOLOGY, Issue 2009L. Paesch Summary The softnose skates Bathyraja brachyurops and Bathyraja macloviana represent an important portion of the skate catches of the Uruguayan trawling fleet in the southwestern Atlantic. From March to October 2004, specimens of these species were collected at 75,200 m depth range in the area situated between latitudes 37°00,,39°30,S. For B. brachyurops, total length at which 50% of the specimens were retained by the gear was 68.0 cm for both sexes; TL50 was estimated at 65.4 cm for males and 67.0 cm for females. For B. macloviana, total length at which 50% of the specimens were retained was 56.0,57.0 cm for both sexes; TL50 was estimated at 53.5 cm for males and 52.0 cm for females. Egg capsule length varied from 79,91 mm in B. brachyurops and 69,75.5 mm in B. macloviana. In both species, capsules displayed striated surfaces and similar gross morphology, although egg capsules of B. macloviana had more robust anterior horns and a smaller size than those of B. brachyurops. Egg capsules of the latter also exhibited microscopical prickles. Capsule edges were laterally keeled with a groove along the keel, and a straight and transverse velum was present in the egg capsules of both species. [source] Site fidelity and movements of humpback whales (Megaptera novaeangliae) on the Brazilian breeding ground, southwestern AtlanticMARINE MAMMAL SCIENCE, Issue 4 2010Leonardo L. Wedekin Abstract Site fidelity and movements were studied for humpback whales photo-identified from 1989 to 2006 in the Abrolhos Bank, southwestern Atlantic, Brazil. A total of 2,612 individuals were identified, 374 of which were observed on more than one occasion. The cumulative number of identified whales has increased since 1989. Recapture rate was low and varied among different years. A total of 33 whales was observed using the Abrolhos Bank for longer than 10 yr, up to a maximum of 16 yr. Our data suggest that different whales show distinct movement rates. Some whales used a large extent of the Abrolhos Bank region. Opportunistic photo-identification data (on the scale of the Brazilian coast from 4° to 23°S) revealed important information about stock identity. The longest distance between within-season resightings was over 600 km, while one whale was observed in two locations separated by more than 1,400 km in different years. Long-range movements within and between seasons support the single stock hypothesis for humpback whales wintering off the Brazilian coast. [source] PERMANENT GENETIC RESOURCES: Development of microsatellite markers for the ecosystem bioengineer mussel Perumytilus purpuratus and cross-priming testing in six Mytilinae generaMOLECULAR ECOLOGY RESOURCES, Issue 2 2008M. PÉREZ Abstract Eight microsatellite markers have been characterized from the Perumytilus purpuratus genome. Their gene diversity ranged from 0.057 to 0.873 and significant interpopulation genic heterogeneity was observed between two populations of southeastern Pacific (Chile) and southwestern Atlantic (Argentine). Distinct cross-priming amplification rates were recovered on nine additional species belonging to six Mytilinae genera. The microsatellites developed herein would likely be a powerful intraspecific genetic tool to undertake fine population studies in the intertidal ecosystem bioengineer P. purpuratus along the South American shoreline. [source] | |||||||||||||