Despite its wide distribution worldwide, only 4.6% of temperate grasslands are included within systems of protected areas. In Argentina, this situation is even more alarming: only 1.05% is protected. ...The study area (central area of the southern Salado River basin) has a large extent of grasslands of
(Pq) which has been target since the middle of the last century of a variety of agricultural management practices including fire burning for cattle grazing.
Five binary images of presence-absence data of Pq from a 42-year range (1974-2016) derived from a land cover change study were used as base data. Morphological Spatial Pattern Analysis (MSPA), Morphological Change Detection (MCD) and Network Connectivity Analysis (NCA) were performed to the data using Guidos Toolbox (GTB) for the estimation of habitat and connectivity dynamics of the Pq patches (fragments).
A loss of the coverage area and habitat nuclei of this grassland was observed during the study period, with some temporal oscillation but no recovery to initial states. Additional drastic reduction in connectivity was also evident in resulting maps. The number of large Pq grassland fragments (>50 ha) decreased at beginning of the study period. Also, fragmentation measured as number of components (patches) was higher at the end of the study period. The Pq pajonal nuclei had their minimum representativeness in 2000, and recovered slightly in area in 2011, but with a significant percentage increase of smaller patches (=islets) and linear elements as bridges and branches. Large corridors (mainly edge of roads) could be observed at the end of the study period, while the total connectivity of the landscape pattern drops continuously. Statistics of links shows mean values decreasing from 1974 to 2016. On the other hand, maximum values of links decreased up to 19% in 2011, and recovered to a 54% of their original value in 2016.
Pq fragmentation and habitat reduction could have an impact on the ecosystem functioning and the mobility of some species of native fauna. The connecting elements of the landscape were maintained and/or recovered in percentage in 2011 and 2016. This fact, although favoring the dispersion of the present diversity in the habitat nuclei could cause degradation by an edge effect. Part of the area has the potential to be taken as an area of research and as an example of livestock management, since it is the one that would most preserve the biodiversity of the Pq environment. On the methodological side, the use of a proved tool as GTB is useful for monitoring dynamics of a grassland-habitat fragmentation.
South America faces strong environmental pressures as a result of agriculture and infrastructure expansion and also of demographic growth, demanding immediate action to preserve natural assets by ...establishing protected areas. Currently, 7.1% of the (sub)continent is under strict conservation categories (I to IV, IUCN), but the spatial distribution of these 1.3 × 10
km
is poorly understood. We evaluated the representation of nature within the networks of protected areas, map conservation priorities and assess demographic, economic or geopolitical causes of existing protection patterns.
We characterized nature representation by looking at two components: the extent and the equality of protection. The first refers to the fraction of territory under protection, while the second refers to the homogeneity in the distribution along natural conditions of this protected fraction. We characterized natural conditions by either 113 biogeographical units (specifically, ecoregions) or a series of limited and significant climatic, topographic and edaphic traits. We analyzed representation every ten years since 1960 at national and continental levels. In the physical approach, histograms allowed us to map the degree of conservation priorities. Finally, we ranked the importance of different economic or geopolitical variables driving the observed distributions with a random forest technique.
Nature representation varied across countries in spite of its priority in conservation agendas. In Brazil, Peru and Argentina there are still natural conditions with no formal protection, while in Bolivia and Venezuela, protected areas incorporate the natural diversity in a more balanced manner. As protected networks have increased their extent, so did their equality across and within countries over time. Our maps revealed as top continental priorities the southern temperate, subhumid and fertile lowland environments, and other country-specific areas. Protection extent was generally driven by a low population density and isolation, while other variables like distance to frontiers, were relevant only locally (e.g., in Argentina).
Our description of the spatial distribution of protected areas can help societies and governments to improve the allocation of conservation efforts. We identified the main limitations that future conservation efforts will face, as protection was generally driven by the opportunities provided by low population density and isolation. From a methodological perspective, the physical approach reveals new properties of protection and provides tools to explore nature representation at different spatial, temporal and conceptual levels, complementing the traditional ones based on biodiversity or biogeographical attributes.
La valoración económica de los recursos naturales ayuda a identificar opciones que permitancompatibilizar el desarrollo de una localidad y la conservación de sus ambientes naturales.Una de las ...metodologías que suele emplearse para estimar dicha valoración es la Disposicióna Pagar (DAP). El objetivo de nuestro trabajo fue evaluar la DAP por los serviciosecosistémicos que brindan dos áreas protegidas de la localidad de Puerto Deseado. Para ellose utilizó el método de valoración de contingente, que a través de la realización de encuestaspermite estimar la DAP de los individuos por la provisión o mejora de un bien ambiental.Para el armado de la encuesta se consideraron diferentes dimensiones: socioeconómicas; depreferencias de visita; estado de las áreas protegidas; problemas detectados; disponibilidad ymodo de pago para conservar el status ambiental de las áreas protegidas. Se encuestó un totalde 126 personas (74 residentes y 52 turistas). Para determinar cuál o cuáles variablesconsideradas pueden determinar la DAP se utilizaron análisis univariados y modelos deregresión logística. El modelo que mejor explicó la DAP incluyó como variables predictivas:lugar de residencia, si posee o no empleo y la percepción sobre el estado de las áreasprotegidas. Según las encuestas, y en comparación a la respuesta de los turistas, la comunidadde Puerto Deseado mostró una mayor disposición a invertir en mantener o mejorar el estadode conservación de ambas áreas. Personas con empleo y con mayor salario mostraron unamayor DAP positiva. Los que están dispuestos a pagar demandan mayor control, vigilancia einfraestructura en las áreas protegidas. La fauna y paisaje local son los principales motivos devisitas, lo que señala la importancia de políticas de gestión tendientes a conservar el entornolo más prístino posible. Se espera que los resultados obtenidos en este trabajo, sumados afuturos, sirvan para que el concepto de valoración de los servicios ecosistémicos pueda seraplicado en una gestión más equitativa y efectiva de las áreas protegidas y sus recursosnaturales.
The use of combined conventional and stable isotope analyses (SIA) to study the diet of seabirds has become very frequent. Unfortunately, information on the trophic ecology of immature seabirds ...remains scarce because the sampling of tissues to perform SIA is often very limited due to the difficulty to capture these birds. The koilin membrane, which covers the regurgitated pellet casts of some seabirds, could offer an interesting non-intrusive alternative tissue to perform SIA. In this two-year study of the diet of imperial cormorants in southern Patagonia, we (1) compare the diets of breeding and non-breeding birds through conventional pellet analysis; (2) describe the diet of breeding adults and chicks through a combined method of pellet analysis and whole blood SIA; and finally, (3) compare SIA values of breeding adults obtained from blood with those obtained from koilin membranes. We found that immature individuals incorporated abundant invertebrate taxons, compared with breeding adults which relied mainly on fish. Younger and inexperienced individuals, which are not under the constraint to feed chicks, are feeding on more predictable, but lower trophic and less energetic prey. By comparing the stable isotope values of koilin and blood in breeding adults, a correlated interannual difference between the two seasons was found. Under the light of our results, the koilin offers an encouraging alternative to blood in the study of trophic ecology, particularly for ages or stages in which capture is not possible.
Se realizó un análisis de isótopos estables en uñas para evaluar la composición de la dieta y el uso estacional de los recursos tróficos en individuos juveniles de Pingüino Patagónico (Spheniscus ...magellanicus) provenientes de las costas de Brasil. El análisis se llevó a cabo sobre las porciones basal y distal de las uñas, correspondientes a la temporada invernal y a la reproductiva, respectivamente, en función del tiempo de integración de la señal isotópica determinado por la tasa de crecimiento de la uña y la fecha de colecta. Se observaron diferencias significativas en las señales isotópicas de las dietas correspondientes a las temporadas reproductiva e invernal, sugiriendo diferencias en las contribuciones relativas de las presas. Durante la temporada invernal en Brasil hubo una alta contribución del calamar Loligo sanpaulensis y de la anchoíta, mientras que durante la temporada reproductiva la contribución de presas fue más diversa, con una alta proporción de peces. Esto se reflejó en una mayor amplitud de nicho isotópico en la dieta reproductiva que en la invernal, indicando un uso más amplio de los recursos tróficos en áreas reproductivas. El consumo de anchoíta es mayor al previamente reportado para individuos juveniles en áreas invernales.
Los pingüinos de las costas argentinas: estado poblacional y conservación Schiavini, Adrián(CONICET Centro Austral de Investigaciones Científicas ,Wildlife Conservation Society); Yorio, Pablo(Wildlife Conservation Society ,CONICET Centro Nacional Patagónico); Gandini, Patricia(Wildlife Conservation Society ,CONICET Centro Nacional Patagónico ,Universidad Nacional de la Patagonia Austral Centro de Investigaciones Puerto Deseado) ...
El Hornero,
08/2005, Letnik:
20, Številka:
1
Journal Article
Recenzirano
Odprti dostop
En las costas de Argentina se reproducen tres especies de pingüinos: el Pingüino de Magallanes (Spheniscus magellanicus), el Pingüino Penacho Amarillo (Eudyptes chrysocome) y el Pingüino Papúa ...(Pygoscelis papua). El Pingüino Rey (Aptenodytes patagonica) se reproducía históricamente en Isla de los Estados y recientemente ha sido registrado allí un individuo incubando un huevo. Este trabajo recopila la información disponible a la fecha sobre la distribución y el estado poblacional de estas especies. Se presenta una síntesis de la información disponible sobre el ciclo reproductivo, la ecología alimentaria y los requerimientos de hábitat del Pingüino de Magallanes y del Pingüino Penacho Amarillo, y una evaluación sobre sus interacciones con actividades humanas y su actual estado de conservación. La revisión está orientada a los aspectos de relevancia para el desarrollo de programas de monitoreo, planes de acción y estrategias regionales de conservación. Finalmente, se presenta una lista de recomendaciones de investigación, conservación y manejo.
Three penguin species breed along the coasts of Argentina: the Magellanic Penguin (Spheniscus magellanicus), the Rockhopper Penguin (Eudyptes chrysocome) and the Gentoo Penguin (Pygoscelis papua). The King Penguin (Aptenodytes patagonica) historically bred at Isla de los Estados, and one individual was recently recorded there incubating an egg. This paper reviews the available information on the distribution and the population status of these penguin species. It also presents a synthesis of the information on the breeding cycle, the feeding ecology and habitat requirements for the Magellanic Penguin and the Rockhopper Penguin, and an evaluation of their interactions with human activities and current conservation status. The review focuses on aspects that are relevant to the development of monitoring programs, action plans and regional conservation strategies. Finally, a list of research, conservation and management recommendations is presented.
The current information about the diet composition of the rock shag (
Phalacrocorax magellanicus
) in the SW Atlantic coast comes mainly from conventional pellet or stomach content analysis from a ...few locations situated in northern Patagonia (Chubut Province, Argentina). In this work, we studied the diet of breeding rock shags over several years at a colony from southern Patagonia (Ría Deseado, Santa Cruz Province, Argentina) using a combined technique of conventional diet assessment (pellet analysis) and stable isotope analysis of carbon and nitrogen. Our results confirm the importance of benthic prey and the low inter-annual variability in the diet of the rock shag. These results coincide with previous research in relation to the exploitation of slow moving, predictable, but low-energy density prey. The stable isotope mixing models, which was informed with prior data obtained from pellet analysis, allowed for the detection of subtle differences between the diet of adults and chicks, consisting in the incorporation of higher proportions of cephalopods, an energy-rich prey, in the diet of chicks. By comparing our results with the diet of the red-legged cormorant, which breeds in sympatry in the Ría Deseado Estuary and whose diet composition is strongly pelagic, we suspect a certain level of trophic resource partitioning between these rock shag and red-legged cormorant.
Penguins are the most threatened group of seabirds after albatrosses. Although penguins are regularly captured in fishing gear, the threat to penguins as a group has not yet been assessed. We ...reviewed both published and grey literature to identify the fishing gear types that penguins are most frequently recorded in, the most impacted species and, for these susceptible species, the relative importance of bycatch compared to other threats. While quantitative estimates of overall bycatch levels are difficult to obtain, this review highlights that, of the worldís 18 species of penguins, 14 have been recorded as bycatch in fishing gear and that gillnets, and to a lesser extent trawls, are the gear types that pose the greatest threats to penguins. Bycatch is currently of greatest concern for yellow-eyed Megadyptes antipodes (Endangered), Humboldt Spheniscus humboldti (Vulnerable) and Magellanic Spheniscus magellanicus penguins (Near Threatened). Penguins face many threats; reducing bycatch mortality in fishing gear will greatly enhance the resilience of penguin populations to threats from habitat loss and climate change that are more difficult to address in the short term. Additional data are required to quantify the true extent of penguin bycatch, particularly for the most susceptible species. In the meantime, it is crucially important to manage the fisheries operating within known penguin foraging areas to reduce the risks to this already threatened group of seabirds.
The use of combined conventional and stable isotope analyses to study the diet of seabirds has become very frequent. Unfortunately species and tissue-specific Trophic Discrimination Factors (TDF), ...necessary to run stable isotope mixing models in the most performing way, are lacking for a wide number of seabird species. We assessed the process of inspecting and selecting the most adequate TDFs by running mixing region simulations with three different TDFs scenarios. This was carried out in a combined dietary study of a widespread but poorly studied seabird from the Americas: the Neotropic Cormorant (
Phalacrocorax brasilianus
), at a breeding colony from coastal Patagonia. The mixing models were run with the best fitting carbon and nitrogen TDFs (whole blood), which were those obtained with R package SIDER, a Bayesian inference-based model predicting the TDFs of consumers considering their ecology and phylogenetic relatedness. We found that cormorants fed on rather mobile fish of a fairly variable ecological spectrum, both benthic and pelagic, and showed low prey diversity. Our results coincide with the overall generalist and opportunistic piscivorous habit found at different coastal areas along its broad distribution range. Despite some differences found in the proportion estimates of the main prey between the two methods, their combination through the incorporation of prior information into the mixing models provides a comprehensive trophic profile. Finally, the use of SIDER, alongside the inspection and comparison of different potential TDF values, offered a simple and effective framework to calculate and select the most adequate specific TDFs to be employed in stable isotope mixing models.
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