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Symptoms of eutrophication in intertidal macroalgal assemblages of Nuevo Gulf (Patagonia, Argentina)
No full textThe city of Puerto Madryn, located within a section of Nuevo Gulf (Patagonia, Argentina) known as Nueva Bay, can be regarded as an important centre of anthropogenic impact. Intertidal assemblages of macroalgae were studied in order to analyse whether eutrophication symptoms could be detected in the benthos. Three rocky shores showing similar characteristics were selected. One of these was located near the sewage outfall of the city of Puerto Madryn. Two control shores were chosen approximately 30 km northwards and southwards of the latter. Four seasonal surveys were performed between June 1998 and April 1999. Biomass data of 35 macroalgal species were analysed by diversity and evenness indices, non-Metric Multidimensional Scaling, and the ANOSIM permutation test. Species responsible for the differences between shores were identified by the SIMPER routine. The macroalgal assemblage of the impacted site was significantly different from those of the two control shores throughout the year. Ulva rigida, Corallina officinalis and Ralfsia sp. were the species mostly responsible for these differences. Results indicate that the impacted shore showed signs consistent with an intermediate degree of eutrophication, particularly the increased abundance of the opportunist green alga Ulva rigida.Fil: Díaz, P.. Universidad Nacional de la Patagonia "San Juan Bosco"; ArgentinaFil: López Gappa, Juan José. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Piriz, Maria Luz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; Argentin
Population features of the invasive kelp Undaria pinnatifida (Phaeophyceae: Laminariales) in Nuevo Gulf (Patagonia, Argentina).
Get PDFThe invasive kelp Undaria pinnatifida was observed for the first time in the Nuevo Gulf (Patagonia, Argentina) in December 1992. At the present time, with the exception of sandy bottoms, the coasts of the Nuevo Gulf are almost entirely colonized. From October 1997 to February 2000, the characteristics of this population, i.e. the relationships between morphological fea- tures and seawater temperature, the seasonality in sporophyll development and the proportions of different reproductive stages during its life cycle, were analysed. The observations confirmed that the maximal mean densities of sporophytes (149.1 plants m 2 2 ) occurred in winter while the mean tallest sporophytes (88.5 cm) and the mean highest biomass (16501 g m 2 2 ) were registered in spring and at the beginning of the summer. Coexisting juvenile and mature sporophytes were found. Sporophylls showed also seasonal characteristics, with maximal width in summer. Manipulative experiments conducted for testing the recruitment pattern of Undaria pinnatifida confirmed that the presence of juvenile individuals was uninterrupted. Thus, in this paper, we denote that U. pinnatifida has a constant recruitment, together with high repro-ductive rates, which are some of the characteristics of an introduced species, which explains why they became a highly invasive species or ‘pest species’, with negative environmental and economic effects.Fil: Casas, Graciela Noemi. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; ArgentinaFil: Piriz, Maria Luz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; ArgentinaFil: Parodi, Elisa Rosalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentina. Universidad Nacional del Sur; Argentin
Changes in biomass and botanical composition of beach-cast seaweeds in a disturbed coastal area from Argentine Patagonia
Get PDFTrends in wrack composition and biomass, and its relationship with the anthropogenic impact were studied along a coastal area in Nuevo Gulf (south Patagonia) in front of Puerto Madryn city. Beach-cast macroalgae composition was sampled from 1992 to 1999 in the Puerto Madryn beaches and in several other nearby beaches in 1993, 1996 and 1998. Historical information was based on local knowledge and observations reported by marine biologists who worked in the area. The botanical composition of the beach-cast macroalgae in Puerto Madryn indicates a succession in the dominance from Codium spp. to Ulva spp. during 1990s and from Ulva to Undaria pinnatifida since 1998, accompanied by a significant decrease in biomass of Gracilaria gracilis and Macrocystis pyrifera. The increase of the opportunist species such as Ulva may be supported by the continuous delivery of waste waters into the Nuevo Gulf while the dominance of U. pinnatifida may be associated with port activities. During the sampling period the highest wrack biomass values were recorded in spring and summer. The beach-cast seaweed biomass harvested by the municipality of Puerto Madryn during beach cleaning operation, ranged between 2500 and 12000 t year -1 (200 and 960 t dry weight). Wrack harvesting produces an environmental impact by removing sand from the beach and affecting coastal communities. Composting of wrack is proposed as one of the environmental alternatives to land disposal.Fil: Piriz, Maria Luz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; ArgentinaFil: Eyras, María Cecilia. Universidad Nacional de la Patagonia "San Juan Bosco"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Rostagno, Cesar Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; Argentin
Latitudinal gradients in macroalgal biodiversity in the Southwest Atlantic between 36 and 55°S
Get PDFDifferent groups of marine benthic organisms show contrasting latitudinal patterns of biodiversity. The widely accepted paradigm of increasing biodiversity towards the tropics does not seem to be valid for macroalgal floras of the Southern Hemisphere. We compiled a database summarizing the distributional ranges of macroalgae along the coast of Argentina to test whether biodiversity decreases towards lower latitudes, as in the Pacific coast of South America, and whether breaking points in the geographical distribution can be recognized in one or more areas of the Southwest Atlantic south of 36°S. We found a clear trend of decreasing biodiversity with decreasing latitude. The interpretation of some biodiversity declines is confounded by changes in the intensity of the sampling effort. A 51% reduction in algal species richness between 42 and 41°S coincides with the boundary between the Argentine and Magellanic Zoogeographic Provinces. This sharp breaking point is related to a thermal anomaly caused by long residence times of water masses within San Matías Gulf, suggesting an upper thermal tolerance limit for most Antarctic/sub-Antarctic seaweeds. A further reduction occurs at 38-37°S. This breaking point can be explained by the disappearance of suitable hard substrata, since rocky outcrops give place to wide extensions of sandy beaches. The impoverished algal assemblage inhabiting the northern coast of Argentina is mainly related to the reduction or disappearance of the Antarctic/sub-Antarctic floristic component. This area is characterised by a predominance of widely distributed species, Chlorophytes and opportunistic filamentous or foliose algae.Fil: Liuzzi, Maria Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; ArgentinaFil: López Gappa, Juan José. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; ArgentinaFil: Piriz, Maria Luz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; Argentin
¿Pueden los pastoreadores nativos de Patagonia, Argentina, consumir al alga invasora Undaria pinnatifida?
Get PDFEl alga invasora Undaria pinnatifida (Phaeophyceae, Laminariales) fue reportada por primera vez en Golfo Nuevo en 1992, dispersándose ampliamente a lo largo de 170 km de costa en el norte de la Patagonia, Argentina. Observaciones de campo hechas en los erizos de mar Arbacia dufresnii y Pseudechinus magellanicus y en el gasterópodo Tegula patagonica evidenciaron que son posibles consumidores de Undaria pinnatifida en la población local. Se realizaron experimentos de laboratorio con el objetivo de probar si estos pastoreadores eran capaces de consumir el alga. Los erizos de mar estudiados consumen el alga, mientras que el gasterópodo ramonea los epibiontes presentes sobre su superficie. Altas densidades de ramoneadores fueron encontradas sobre el alga durante el verano y podrían ser atribuidas a un aumento del su metabolismo con el aumento de la temperatura y a la degradación de las láminas y esporofilos, lo cual posiblemente aumente la palatabilidad del alga.The invasive kelp Undaria pinnatifida (Phaeophyceae, Laminariales) was first reported in Golfo Nuevo in 1992 and since then it has spread widely over more than 170 km, all along the northern Patagonian coast, Argentina. Field observations in the region have indicated the potential role of invertebrate grazers, like the sea urchins Arbacia dufresnii and Pseudechinus magellanicus and the gastropod Tegula patagonica, in controlling algal density. Laboratory experiments were conducted to ascertain whether, and if so, to what extent these grazers actually feed on the algae. The studied sea urchins fed on the alga, whereas the snail scraped off biofouling adhered to its surface. Higher densities of grazers were observed on the kelp during summer and might be attributed to increasing in metabolism with increasing temperature, and degradation of blades and sporophylls, which possibly increase their palatability.Fil: Teso, Silvia Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; ArgentinaFil: Bigatti, Gregorio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Casas, Graciela Noemi. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Piriz, Maria Luz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Penchaszadeh, Pablo Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; Argentin
Utilización de las macroalgas marinas de la costa argentina y sus hidrocoloides
No full textLas algas marinas han sido explotadas y utilizadas por centurias en agricultura, ganadería, alimentación humana y animal, en la industria farmacéutica y como materia prima para la producción de substancias gelificantes y/o viscosantes de uso industrial. En la actualidad las especies de algas explotadas comercialmente a gran escala en todo el mundo no llegan a 100. Hasta la década de 1970 la contribución de la maricultura a la producción de mundial de algas marinas era escasa, pero actualmente la situación ha cambiado substancialmente y el ficocultivo es uno de los aspectos más importantes de la maricultura mundial Las algas utilizadas para la industria son de precio relativamente bajo, aunque el valor agregado puede ser elevado; las usadas directamente en alimentación humana son, en cambio, caras y su valor agregado es relativamente bajo. En el presente capítulo se describen los resultados de la investigación aplicada referida a las especies de algas comerciales de la costa patagónica de Argentina y de sus productos y se resume la evolución de la actividad económica relacionada con la explotación de sus poblaciones naturales.Fil: Boraso, Alicia Lilian. Universidad Nacional de la Patagonia "San Juan Bosco"; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro de Investigaciones y Transferencia Golfo San Jorge. Centro de Investigaciones y Transferencia Golfo San Jorge: Sede Caleta Olivia - Santa Cruz | Universidad Nacional de la Patagonia Austral. Centro de Investigaciones y Transferencia Golfo San Jorge. Centro de Investigaciones y Transferencia Golfo San Jorge: Sede Caleta Olivia - Santa Cruz | Universidad Nacional de la Patagonia "san Juan Bosco". Centro de Investigaciones y Transferencia Golfo San Jorge. Centro de Investigaciones y Transferencia Golfo San Jorge: Sede Caleta Olivia - Santa Cruz; ArgentinaFil: Ciancia, Marina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones en Hidratos de Carbono. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones en Hidratos de Carbono; ArgentinaFil: Cerezo, Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Piriz, Maria Luz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Casas, Graciela Noemi. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Eyras, María Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentin
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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