Condrictios de la Argentina y Uruguay: lista de trabajo

Presentamos aquí una lista actualizada de los condrictios (tiburones, rayas, quimeras y pez elefante) que han sido citados de la Argentina y Uruguay, incluyendo las especies de agua dulce de la familia Potamotrygonidae. Cuando una especie está presente en Argentina o en Uruguay, se lo indica a continuación de la especie; las demás, son compartidas. No se indica la distribución de las especies en otras áreas. Muchas de las especies conocidas de Uruguay terminan allí su distribución meridional, y ocasionalmente algunas entran a aguas argentinas y otras podrían hacerlo. Estas presencias ocasionales parecen no ser muy comunes. La progresiva disminución de las capturas de Dasyatis violacea con la disminución de temperatura hacia el sur ha sido demostrada (Domingo et al., 2005). En 1981 Menni publicó una lista de las familias de peces que no sobrepasaban la latitud del Río de La Plata, y de los condrictios mencionados, Orectolobidae, Ginglymostomatidae y Rhinopteridae, sólo una especie de la última familia ha sido citada en años recientes de Uruguay. Al contrario, especies que han sido citadas de la Argentina, como Sphyrna tudes de Mar del Plata por Berg (1895) o Narcine brasiliensis de la provincia de Buenos Aires por Lahille (1928), no han sido halladas de nuevo. La lista está basada en el catálogo crítico de Menni et al. (1984), y se han hecho las modificaciones taxonómicas necesarias y agregado las especies nuevas para el área. Debido al carácter práctico de esta lista, sólo se incluyen los autores de las especies y la fecha de su descripción. En los nuevos registros se agrega un breve comentario fundamentando la inclusión. Estando disponible el catálogo de Eschmeyer (1998) y su versión on-line, nos pareció que más detalles eran innecesarios. En la macrosistemática de los holocéfalos se sigue a Didier (2004), en la de los tiburones a Compagno (2005) y en la de los batoideos a McEachran & Aschliman (2004). Para las especies de Uruguay se ha seguido principalmente a Nion et al. (2002) y a Meneses y Paesch (1997), y deben mencionarse los trabajos anteriores de Ximénez (1962) y de Carrera (1991) que proveen referencias previas. La bibliografía se limita a trabajos generales que pueden ser de utilidad, los trabajos en que se basan las nuevas referencias, y los que corresponden a comentarios. No se han incluido numerosos trabajos sobre biología y ecología de estos organismos, que han modificado mucho la información resumida en Menni (1986), pero sí algunos que muestran cambios considerables de distribución. (PDF tiene 18 paginas.

Food habits, selectivity, and foraging modes of the school shark Galeorhinus galeus

The foraging ecology of the school shark Galeorhinus galeus was studied in Anegada Bay, Argentina, during the seasonal occurrence of this species in Argentinean waters (October to April) from 1998 to 2001. Of the 408 individuals examined, 168 (41.2%) had food remains in their stomachs. The proportion of individuals with food remains was negatively correlated with total length. In general, the diet was composed mainly of teleosts (98.5% IRI [index of relative importance]), with invertebrates and chondrichthyans as minor prey. The diet varied ontogenetically and seasonally. Juveniles and adults differed in their consumption of invertebrates, with juveniles preying more on benthic invertebrates, mainly the octopus Octopus tehuelchus, and adults on squid. From December to February, adults preyed mainly on benthic teleosts (almost exclusively the Atlantic midshipman Porichthys porosissimus), while from March to April the consumption of squid increased. A comparison of numbers of prey in stomachs with abundance of prey in the environment in March and April showed that, in these months, juveniles selected invertebrates and demersal teleosts and avoided pelagic teleosts and chondricthyan prey, and adults selected squid and avoided pelagic teleosts. This indicates that, during this period, G. galeus is not an opportunistic predator. The mean size of prey increased with increasing shark length, but even large sharks consumed small prey. All shark sizes consumed prey fragments that were significantly larger than other prey consumed whole. This indicates that G. galeus is able to overcome gape limitation by mutilating prey, and that the ontogenetic diet shift was not due to a change in the ability to seize prey.Facultad de Ciencias Naturales y Muse

De la coexistencia a la exclusión competitiva: ¿Puede la sobrepesca cambiar el resultado de la competencia en rayas (Chondrichthyes, Rajidae)?

Competition for food could be a major force driving changes in the community structure of skates (Rajidae) subjected to fishing exploitation. Under this hypothesis, small skates are released from competition with larger skates after fishing has depleted the larger species. Here, we compare the abundance patterns of two sympatric skates with similar niches but different life histories, Bathyraja albomaculata (larger and slow-reproducing) and Bathyraja macloviana (smaller and faster-reproducing), before (1971, 1978) and after (1998-2004) a 108% increase in industrial bottom trawling on the southeastern South American shelf in order to test the prediction that B. macloviana should competitively exclude B. albomaculata after the increase in fishing mortality. In 1971 and 1978, there was no relationship between the abundance of both species, indicating that they coexisted over large scales. In 1998-2004, the relationship between the abundances of these skates was bell-shaped, indicating that both species increased in abundance at low densities until peaking, after which B. albomaculata decreased when B. macloviana became more abundant, consistent with resource competition. We tested whether food may be a potential limiting resource by comparing the diet of both species. The two species consumed mostly polychaetes, differing only in the consumption of polychaetes from the family Nephthyidae, which was much higher for B. macloviana. Bathyraja macloviana could replace B. albomaculata at high densities when food resources may become scarce. These results support the hypothesis that competition release is an important factor explaining the changes in skate communities in overexploited areas.La competencia por el alimento podría ser una fuerza importante detrás de los cambios en la estructura de las comunidades de rayas (Rajidae) bajo explotación pesquera. Según esta hipótesis, las rayas pequeñas son liberadas de la competencia por las rayas de mayor tamaño, al disminuir la abundancia de éstas últimas por la pesca. En este trabajo, se comparan los patrones de abundancia de dos rayas simpátricas con nichos similares pero con diferentes historias de vida, Bathyraja albomaculata (mayor y de reproducción lenta) y Bathyraja macloviana (más pequeña y de reproducción más rápida), antes (1971, 1978) y después (1998-2004) de un incremento del 108% en el arrastre de fondo industrial en la plataforma sudeste de América del Sur, para evaluar la predicción que B. macloviana excluiría competitivamente a B. albomaculata después del aumento en la mortalidad por pesca. En 1971 y 1978, no hubo relación entre las abundancias de ambas especies, indicando que, a escalas grandes, coexistían. En 1998-2004, la relación entre las abundancias de ambas especies tuvo forma de campana, indicando que ambas incrementaron su abundancia a densidades bajas hasta alcanzar un máximo, a partir del cual la abundancia de B. albomaculata disminuyó a medida que aumentaba la de B. macloviana, patrón consistente con la competencia por uso de recursos. Se evaluó si el alimento puede ser un recurso limitante mediante la comparación de la dieta de ambas especies. Ambas especies consumieron predominantemente poliquetos y difirieron sólo en el consumo de poliquetos Nephthyidae, mucho mayor en B. macloviana. B. macloviana remplazaría a B. albomaculata a altas densidades, cuando el alimento podría ser escaso. Estos resultados apoyan la hipótesis de que la liberación de la competencia es un factor importante en los cambios en las comunidades de rayas sobreexplotadas.Museo de La Plat

Food habits, selectivity, and foraging modes of the school shark Galeorhinus galeus

The foraging ecology of the school shark Galeorhinus galeus was studied in Anegada Bay, Argentina, during the seasonal occurrence of this species in Argentinean waters (October to April) from 1998 to 2001. Of the 408 individuals examined, 168 (41.2%) had food remains in their stomachs. The proportion of individuals with food remains was negatively correlated with total length. In general, the diet was composed mainly of teleosts (98.5% IRI [index of relative importance]), with invertebrates and chondrichthyans as minor prey. The diet varied ontogenetically and seasonally. Juveniles and adults differed in their consumption of invertebrates, with juveniles preying more on benthic invertebrates, mainly the octopus Octopus tehuelchus, and adults on squid. From December to February, adults preyed mainly on benthic teleosts (almost exclusively the Atlantic midshipman Porichthys porosissimus), while from March to April the consumption of squid increased. A comparison of numbers of prey in stomachs with abundance of prey in the environment in March and April showed that, in these months, juveniles selected invertebrates and demersal teleosts and avoided pelagic teleosts and chondricthyan prey, and adults selected squid and avoided pelagic teleosts. This indicates that, during this period, G. galeus is not an opportunistic predator. The mean size of prey increased with increasing shark length, but even large sharks consumed small prey. All shark sizes consumed prey fragments that were significantly larger than other prey consumed whole. This indicates that G. galeus is able to overcome gape limitation by mutilating prey, and that the ontogenetic diet shift was not due to a change in the ability to seize prey.Facultad de Ciencias Naturales y Muse

Competenze Infermieristiche Distintive in Area Ematologica: survey sulla loro diffusione

La natura specialistica dell’Ematologia richiede comprensione dei processi patologici, degli appropriati interventi terapeutici e dell’impatto che essi hanno sulla qualità di vita dei pazienti. Interventi infermieristici mirati in Ematologia richiamano il concetto di Competenze distintive. Questo studio si propone quindi di indagare la diffusione di queste tra gli Infermieri di Ematologia. È stato eseguito uno studio osservazionale multicentrico trasversale, con somministrazione di un questionario a risposta multipla ad un campione appartenente a 3 diverse Unità Operative di Ematologia Adulti delle province di Milano e Monza e Brianza. In base alla percentuale di risposte corrette alle domande del questionario, si può desumere che, tra i soggetti coinvolti nello studio, vi sia una buona diffusione delle Competenze distintive in Ematologia, ma questa appare strettamente legata all’esperienza professionale in questo ambito specifico. Si auspica che l’apprendimento di queste in futuro possa essere correlato anche ad una formazione specialistica post-base.Hematology's specialized nature requires understanding disease processes, appropriate therapeutic interventions, and their impact on a patient's quality of life. Targeted nursing interventions in Hematology invoke the concept of Distinctive Competencies. Therefore, this study aimed to investigate its prevalence among Hematology nurses. A multicenter cross-sectional observational study was performed, administering a multiple-choice questionnaire to a sample belonging to 3 different Adult Hematology Operating Units in Milan and Monza & Brianza. Based on the percentage of correct answers to the questions in the questionnaire, it can be inferred that, among those involved in the study, there is a good diffusion of Distinctive Competencies in Hematology, but this appears to be closely related to professional experience in this field. Hopefully, these learnings will also be related to specialized post-basic training in the future

De la coexistencia a la exclusión competitiva: ¿Puede la sobrepesca cambiar el resultado de la competencia en rayas (Chondrichthyes, Rajidae)?

Competition for food could be a major force driving changes in the community structure of skates (Rajidae) subjected to fishing exploitation. Under this hypothesis, small skates are released from competition with larger skates after fishing has depleted the larger species. Here, we compare the abundance patterns of two sympatric skates with similar niches but different life histories, Bathyraja albomaculata (larger and slow-reproducing) and Bathyraja macloviana (smaller and faster-reproducing), before (1971, 1978) and after (1998-2004) a 108% increase in industrial bottom trawling on the southeastern South American shelf in order to test the prediction that B. macloviana should competitively exclude B. albomaculata after the increase in fishing mortality. In 1971 and 1978, there was no relationship between the abundance of both species, indicating that they coexisted over large scales. In 1998-2004, the relationship between the abundances of these skates was bell-shaped, indicating that both species increased in abundance at low densities until peaking, after which B. albomaculata decreased when B. macloviana became more abundant, consistent with resource competition. We tested whether food may be a potential limiting resource by comparing the diet of both species. The two species consumed mostly polychaetes, differing only in the consumption of polychaetes from the family Nephthyidae, which was much higher for B. macloviana. Bathyraja macloviana could replace B. albomaculata at high densities when food resources may become scarce. These results support the hypothesis that competition release is an important factor explaining the changes in skate communities in overexploited areas.La competencia por el alimento podría ser una fuerza importante detrás de los cambios en la estructura de las comunidades de rayas (Rajidae) bajo explotación pesquera. Según esta hipótesis, las rayas pequeñas son liberadas de la competencia por las rayas de mayor tamaño, al disminuir la abundancia de éstas últimas por la pesca. En este trabajo, se comparan los patrones de abundancia de dos rayas simpátricas con nichos similares pero con diferentes historias de vida, Bathyraja albomaculata (mayor y de reproducción lenta) y Bathyraja macloviana (más pequeña y de reproducción más rápida), antes (1971, 1978) y después (1998-2004) de un incremento del 108% en el arrastre de fondo industrial en la plataforma sudeste de América del Sur, para evaluar la predicción que B. macloviana excluiría competitivamente a B. albomaculata después del aumento en la mortalidad por pesca. En 1971 y 1978, no hubo relación entre las abundancias de ambas especies, indicando que, a escalas grandes, coexistían. En 1998-2004, la relación entre las abundancias de ambas especies tuvo forma de campana, indicando que ambas incrementaron su abundancia a densidades bajas hasta alcanzar un máximo, a partir del cual la abundancia de B. albomaculata disminuyó a medida que aumentaba la de B. macloviana, patrón consistente con la competencia por uso de recursos. Se evaluó si el alimento puede ser un recurso limitante mediante la comparación de la dieta de ambas especies. Ambas especies consumieron predominantemente poliquetos y difirieron sólo en el consumo de poliquetos Nephthyidae, mucho mayor en B. macloviana. B. macloviana remplazaría a B. albomaculata a altas densidades, cuando el alimento podría ser escaso. Estos resultados apoyan la hipótesis de que la liberación de la competencia es un factor importante en los cambios en las comunidades de rayas sobreexplotadas.Museo de La Plat

Immunohistochemical investigations on Brucella ceti-infected, neurobrucellosis-affected striped dolphins (Stenella coeruleoalba)

Bacteria of the genus Brucella cause brucellosis, an infectious disease common to humans as well as to terrestrial and aquatic mammals. Since 1994 several cases of Brucella spp. infection have been reported in marine mammals worldwide. Indeed, since human brucellosis ranks as one of the most common bacterial zoonotic infections on a global scale, it is necessary to increase our knowledge about it also in the marine environment. Brucella ceti, which is phenotypically similar to other smooth brucellae as B. abortus and B. melitensis, shares with the latter two the same surface antigens that are routinely used for the serological diagnosis of Brucella spp. infection. Marine mammal Brucella spp. infections are characterized by a pathogenicity similar to their terrestrial counterparts, with the occurrence of abortion, stillbirth and orchitis and an involvement of the host’s central nervous system (CNS), similarly to what happens in mankind. While sero-epidemiological data suggest that Brucella spp. infection is widespread globally, detecting Brucella spp.-associated antigens by immunohistochemistry (IHC) in tissues from infected animals is often troublesome. The present study was aimed at investigating, by means of IHC based upon the utilization of an anti-Brucella LPS monoclonal antibody (MAb), the CNS immunoreactivity (IR) shown by B. ceti-infected, neurobrucellosis-affected striped dolphins

ProBiota | Serie Técnica y Didáctica | Condrictios de la Argentina y Uruguay : Lista de trabajo

Presentamos aquí una lista actualizada de los condrictios (tiburones, rayas, quimeras y pez elefante) que han sido citados de la Argentina y Uruguay, incluyendo las especies de agua dulce de la familia Potamotrygonidae. Cuando una especie está presente en Argentina o en Uruguay, se lo indica a continuación de la especie; las demás, son compartidas. No se indica la distribución de las especies en otras áreas. Muchas de las especies conocidas de Uruguay terminan allí su distribución meridional, y ocasionalmente algunas entran a aguas argentinas y otras podrían hacerlo. Estas presencias ocasionales parecen no ser muy comunes. La progresiva disminución de las capturas de Dasyatis violacea con la disminución de temperatura hacia el sur ha sido demostrada (Domingo et al., 2005). En 1981 Menni publicó una lista de las familias de peces que no sobrepasaban la latitud del Río de La Plata, y de los condrictios mencionados, Orectolobidae, Ginglymostomatidae y Rhinopteridae, sólo una especie de la última familia ha sido citada en años recientes de Uruguay. Al contrario, especies que han sido citadas de la Argentina, como Sphyrna tudes de Mar del Plata por Berg (1895) o Narcine brasiliensis de la provincia de Buenos Aires por Lahille (1928), no han sido halladas de nuevo. La lista está basada en el catálogo crítico de Menni et al. (1984), y se han hecho las modificaciones taxonómicas necesarias y agregado las especies nuevas para el área. Debido al carácter práctico de esta lista, sólo se incluyen los autores de las especies y la fecha de su descripción. En los nuevos registros se agrega un breve comentario fundamentando la inclusión. Estando disponible el catálogo de Eschmeyer (1998) y su versión on-line, nos pareció que más detalles eran innecesarios. En la macrosistemática de los holocéfalos se sigue a Didier (2004), en la de los tiburones a Compagno (2005) y en la de los batoideos a McEachran & Aschliman (2004).Facultad de Ciencias Naturales y Muse

Spatial patterns in the diversity of sharks, rays, and chimaeras (Chondrichthyes) in the Southwest Atlantic

Knowing how the diversity of sharks, rays and chimaeras (Chondrichthyes) is distributed helps us to design strategies to conserve these highly-vulnerable predators and their habitats. Here, we analyzed the spatial distribution of chondrichthyan species richness in the Southwest Atlantic (34-56 oS), and its relationship with environmental variables and marine fronts, by using a dataset obtained before the major development of industrial trawling fisheries. We also explored the relationship between richness and reported catches of chondrichthyans from commercial, demersal fisheries. Generalized linear models were used to assess the relationship of species richness with environmental variables; with marine fronts and with commercial catches. Species richness increased towards the north, particularly close inshore and on the outer shelf, with cells of highest richness found north of 48 oS. Dissolved oxygen was related negatively with richness; depth, latitude and longitude were also related with richness, but to a lesser extent. Chondrichthyan diversity hotspots, i. e. cells with richness higher than the 90% percentile of the richness distribution, were more likely to occur on marine fronts than elsewhere. High chondrichhtyan catches were significantly associated to hotspots, but low-catch areas were not related to coldspots, i. e. cells with less than the 10% percentile of the richness distribution. Areas of high richness of chondrichthyans coincide with high levels of catches and are used by other species of high conservation concern. Given the importance of these areas to multiple species in the Southwest Atlantic, any conservation strategy based on a network of protected areas should include marine fronts.Fil: Lucifora, Luis Omar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Puerto Iguazú | Universidad Nacional de Misiones. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Puerto Iguazú; ArgentinaFil: García, Verónica Beatriz. Dalhousie University Halifax; CanadáFil: Menni, Roberto Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Departamento Científico Zoología Vertebrados; ArgentinaFil: Worm, Boris. Dalhousie University Halifax; Canad

Marine biodiversity at the community level: Zoogeography of sharks, skates, rays and chimaeras in the southwestern Atlantic

For more than a century, two major zoogeographic provinces have been proposed for the southwestern Atlantic: A warm water Argentinean Province from Rio de Janeiro (23°S, Brazil) to Valdés Peninsula (42°S, Argentina), and a cold water Magellanic Province from Valdés Peninsula to Cape Horn. This zoogeographic scheme has been recognized so far using data covering only parts of the whole geographic area. Here, we test the validity of this scheme by analyzing the distribution of sharks, skates, rays and chimaeras, using data from research cruises covering the entire area. We used cluster, similarity and dissimilarity analyses to identify species assemblages, and canonical correspondence analysis to identify the main environmental variables affecting the composition of the assemblages. The distribution of chondrichthyan assemblages strongly supports the current zoogeographic scheme and identifies a previously unknown and distinctive deep water zoogeographic unit off southern Brazil. Both, the Argentinean and Magellanic Provinces had extensive internal structure, with four and three subareas identified in each of them, respectively. These subareas correspond, with slight differences, to previously proposed zoogeographical districts within the Argentinean Province and confirm ecological differences within the Magellanic Province. Species composition had the highest correlation with depth and bottom water temperature. Since the distribution of anthropogenic disturbances in the region is uneven, different assemblages can be subjected to different impacts. Our results provide an objective basis to establish priority areas for the conservation of chondrichthyans in the southwestern Atlantic.Fil: Menni, Roberto Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo ; ArgentinaFil: Jaureguizar, Andrés Javier. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión de Investigaciones Científicas, Instituto Nacional de Investigación y Desarrollo Pesquero; ArgentinaFil: Stehmann, Mathias F. W.. Ichthys Consultant; AlemaniaFil: Lucifora, Luis Omar. Centro de Investigaciones del Bosque Atlántico; Argentina. Universidad Nacional del Nordeste; Argentin