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Acceso Abierto Las incrustaciones biológicas del puerto de Mar del Plata (Argentina): periodo 1976/77(1980) Stupak, Mirta E.; Bastida, Ricardo; Arias, Pablo J.Cuando se iniciaron en 1964 las investigaciones sobre las comunidades incrustantes de las costas argentinas, se tomó como principal área de estudios al puerto de Mar del Plata. Ello respondía básicamente a la importancia del mismo como puerto pesquero, comercial y táctico, como así también su proximidad con los institutos vinculados con los diversos aspectos de las investigaciones proyectadas. Los estudios realizados durante el mencionado período seguramente convierten al puerto de Mar del Plata en el mejor conocido de toda Latinoamérica en cuanto a la dinámica de sus comunidades incrustantes. Las investigaciones realizadas hasta el presente han comprendido tanto aspectos ecológicos generales de la comunidad como también estudios particulares sobre organismos de especial interés desde el punto de vista aplicado. Estos estudios se llevaron a cabo por períodos anuales, empleando para ello sustratos artificiales sobre balsas experimentales y complementados en muchos casos con experiencias de laboratorio, observaciones de sustratos naturales, etc. El presente trabajo constituye el resultado de una nueva experiencia anual (1976/77) mediante el empleo de balsa experimental que complementa el panorama obtenido en años previos sobre el conjunto de la comunidad incrustante local. El mismo constituye el último ensayo de tipo general sobre la comunidad a realizarse en la zona, ya que se considera cubierto el panorama básico local. Los esfuerzos futuros a desarrollar en este puerto se limitarán, en lo que hace a los aspectos biológicos, a investigaciones particulares sobre especies incrustantes de alta resistencia tóxica. La tarea realizada inicialmente en el puerto de Mar del Plata ha sido proseguida en otras áreas portuarias de Argentina, con la finalidad de conocer las características de este problema en los principales puertos de nuestra extensa costa marítima. - Artículo
Acceso Abierto From fresh water to the slope: fish community ecology in the Río de la Plata and the sea beyond(Universidad Católica de Valparaíso, 2010) García, Mirta L.; Jaureguizar, Andrés Javier; Protogino, Lucila C.The spatial pattern of fish assemblages and its relationship with factors along an environment gradient, from fresh to marine water environment along the Río de la Plata estuary (36ºS, 56ºW) the shelf and part of the slope, was examined using data from 22 sampling stations. Fish were sampled from all station with an Engel type trawl (200 mm stretched mesh in the wings, 120 mm stretched mesh in the cod ends, 4 m vertical opening and 15 m horizontal aperture) towed at 4 knots for 20 to 30 min per set. Cluster analysis and ordination analysis MDS were used to define spatial distribution of fish assemblages based on fish composition (abundance and biomass). BIO-ENV process was used to estimate assemblage association with depth, temperature and salinity of surface and bottom waters. The results of these analyses showed that the fish community along the riverine-marine gradient was structured in four assemblages: riverine, estuarine, shelf and slope. These assemblages were found to differ significantly in their species composition. Each assemblage was characterized by several common and discriminator species and characterized by differing environmental conditions. Bottom salinity and bottom temperature were the environmental variables most strongly associated with differences in assemblage structure across the various areas. The changes in assemblage structure between areas were gradual, with no sharp boundaries. - Artículo
Acceso Abierto Fish assemblages in a small temperate estuary on the Argentinian coast: spatial variation, environmental influence and relevance as nursery area(Universidade de São Paulo, Instituto Oceanográfico, 2015) Solari, Agustín; Jaureguizar, Andrés Javier; Milessi, Andres Conrado; García, Mirta L.The effects of different environmental variables on the fish community structure were evaluated in a small temperate estuary. The biological and environmental data were collected bimonthly between 2007 and 2009 along the main estuarine axis. Multivariate analyses were applied (CLUSTER, SIMPER, CCA) to determine the spatial structure of fish community and to estimate the environmental influence on it. A total of 48 species of teleost fishes were observed, with the families Characidae and Sciaenidae presenting the largest number of species, 90% of the catches being juveniles. The fish community was overwhelmingly dominated by one species (Micropogonias furnieri, 88.9%), and only four species contributed more than 1% of total catch (Odontesthes argentinensis 5.4%, Brevoortia aurea 1.1%, Paralonchurus brasiliensis 1.1%, and Mugil platanus 1.0%). Estuarine and freshwater stragglers dominated in number of species, followed by freshwater migrants and marine migrants. Three areas with different fish assemblages, with distinctive species and functional guilds, were defined along the main axis. The occurrence and spatial spread of these areas were linked to spatial variation in salinity, which was consistently influenced by discharge from the Río de la Plata and local precipitation. The results highlight the importance of shallow environments as nursery areas and permit emphasis on their susceptibility to environmental changes. - Comunicacion
Acceso Abierto Extensión del límite austral de distribución de tres especies de peces óseos tropicales en la costa de la Provincia de Buenos Aires, Argentina(Pontificia Universidad Católica de Valparaíso, 2012) Milessi, Andres Conrado; Colonello, Jorge H.; Cortés, Federico; Lasta, Carlos Ángel; Waessle, Juan A.; Allega, LucreciaSe presentan tres nuevos registros de especies de peces óseos cuya distribución corresponde a aguas tropicales, capturados por buques pesqueros en la costa de la Provincia de Buenos Aires, Argentina (CPBA, 36º-38ºS). Los ejemplares corresponden a las especies: Rachycentrum canadum, Elops saurus y Caulolatilus chrysops. Estos registros amplían significativamente el límite austral de su distribución. La presencia ocasional de estas especies está asociada al transporte de agua subtropical cálida proveniente de la plataforma continental brasilera. Esta hipótesis es probada mediante el análisis de imágenes satelitales de temperatura superficial del mar. - Artículo
Acceso Abierto Fish fauna from the Ajó river in Campos del Tuyú National Park, province of Buenos Aires, Argentina(2009) Solari, Agustín; García, Mirta L.; Jaureguizar, Andrés JavierWe provide the first list of the ichthyofauna from the Ajó river, a water course situated at the southward border of the Samborombón bay (36°20'12 ’ S, 56°54'17 W), a RAMSAR site in Argentina. These results were obtained bi-monthly along two years. Forty-five species belonging to 26 families and 11 orders were identified. This fish fauna is composed by freshwater, euryhaline and marine species. Richest groups were Perciformes and Characiformes, with 10 species each. A single species, Micropogonias furnieri (whitemouth croaker), represented more than 70 % of the captured specimens, being juvenile individuals only. Remaining species were also represented by juvenile specimens, confirming the importance of this environment as nursery area, particularly for the whitemouth croaker. - Documento de conferencia
Acceso Abierto First optical observations in the turbidity maximum zone in the Río de la Plata estuary: a challenge for atmospheric correction algorithms(2014) Dogliotti, Ana Inés; Camiolo, Martina; Simionato, Claudia; Jaureguizar, Andrés Javier; Guerrero, Raúl Alberto; Lasta, Carlos ÁngelThe Río de la Plata (RdP) estuary, located at 35°S on the southwestern Atlantic Ocean, is a shallow and large-scale plain, which drains the second largest basin in South America. The RdP river carries high amounts of nutrients, suspended particulate and dissolved organic matter to the adjacent shelf waters and is considered among the most turbid estuaries in the world. A turbidity maximum and a sharp surface front defining its seaward edge is a distinctive feature of this estuary. Such high sediment loads represent a challenge to atmospheric correction algorithms which usually rely on the assumption of zero waterleaving reflectance in the near infrared (NIR) or short wave infrared (SWIR) parts of the spectrum. Uncertainties of the primary remote sensing products have never been quantified in RdP before due to lack of in situ measurements. In February and April 2013 two field campaigns were performed in the turbidity maximum zone where water reflectance was measured and surface water samples were collected for turbidity and total suspended particle concentration determinations. A match-up analysis was performed to evaluate the performance of five atmospheric correction algorithms on MODIS-Aqua data that use the NIR and/or SWIR bands to estimate the aerosols optical properties in a pixel-by-pixel basis and from clear water pixels and then applied to the whole image. Satellite retrievals of remote sensing reflectance at the visible bands of Aqua sensor generally showed quite large uncertainties and constant underestimation (largest at the blue bands), whereas the uncertainties in the NIR bands were the lowest. - Artículo
Acceso Abierto Feding and reproductive activity of the copepods Drepanopus forcipatus and Calanus australis during late summer on the Southern Patagonian shelf (Argentina, 47°-55°S)(Universidade de São Paulo. Instituto Oceanográfico, 2014) Antacli, Julieta Carolina; Sabatini, Marina E.; Silva, Ricardo I.; Hernández, Daniel R.; Jaureguizar, Andrés Javier; Akselman, RutDrepanopus forcipatus and Calanus australis are key planktonic copepods on the southern Patagonian shelf. Their feeding and reproductive patterns and population status were investigated during late summer, when environmental conditions may be critical. The presence of food in the gut and food-pellet length were recorded in adult females and the most abundant copepodite stages. Diet composition was also studied in adult females. Female reproductive status was evaluated by gonad staging. Despite generally low feeding conditions and decreasing seasonal temperature, both copepods fed to some degree. The most numerous copepodites and adult females of both species showed similarly low feeding activity. About half of the adult females of the two species and C5s of C. australis contained food in their guts, but the proportion of fed C4-females of D. forcipatus was much lower. All copepods were generally feeding at low or intermediate levels. Gonad stage distribution and population structure showed low but still ongoing reproduction in both species. Gut content findings suggest a preference for smaller nanoplanktonic particles, especially dinoflagellates by D. forcipatus, and for autotrophic prey, particularly large diatoms by C. australis. The feeding and reproduction patterns of the two copepods were likely influenced by the distributions of potential food resources and temperature.