198 resultados para Mosaics
Resumo:
Intermittent stream systems create a mosaic of aquatic habitat that changes through time, potentially challenging freshwater invertebrate dispersal. Invertebrates inhabiting these mosaics may show stronger dispersal capacity than those in perennial stream systems. To relate different combinations of dispersal and drought survival strategies to species persistence, we compared the distribution and dispersal potential of six invertebrate species across all streams in a montane landscape where drying is becoming increasingly frequent and prolonged. Invertebrates were collected from seventeen streams in the Victoria Range, Grampians National Park, Victoria, Australia. The species analysed were as follows: the caddisflies Lectrides varians Moseley (Leptoceridae) and Agapetus sp. (Glossosomatidae); the mayflies Nousia AV1 and Koorrnonga AV3 (Leptophlebiidae); the water penny beetle Sclerocyphon sp. (Psephenidae); and a freshwater crayfish Geocharax sp. nov. 1 (Parastacidae). These species were widespread in the streams and varied in their dispersal and drought survival strategies. The distribution of each species across the Victoria Range, their drought responses and within-stream habitat associations were determined. Hypotheses of the dispersal capacity and population structure for each species were developed and compared to four models of gene flow: Death Valley Model (DVM), Stream Hierarchy Model (SHM), Headwater Model (HM) or panmixia (PAN). Molecular genetic methods were then used to infer population structure and dispersal capacity for each species. The large caddisfly Lectrides resisted drought through aestivation and was panmictic (PAN) indicating strong dispersal capacity. Conversely, the small caddisfly Agapetus relied on perennially flowing reaches and gene flow was limited to short distances among stream headwaters, resembling the HM. Both mayflies depended on perennial surface water during drying and showed evidence of gene flow among streams: Koorrnonga mainly dispersed along stream channels within catchments, resembling the SHM, whereas Nousia appeared to disperse across land by adult flight. Sclerocyphon relied on perennial water to survive drying and showed an unusual pattern of genetic structure that indicated limited dispersal but did not resemble any of the models. Geocharax survived drought through aestivation or residence in perennial pools, and high levels of genetic structure indicated limited dispersal among streams, resembling the DVM. Despite good knowledge of species' drought survival strategies, the population structure of four species differed from predictions. Dispersal capacity varied strongly among species; most species were poor dispersers and only one species showed panmixia. Therefore, intermittent stream species may not necessarily be better dispersers than those in perennial streams. Species showing strong drought resistance strategies differed in dispersal capacity. Knowledge of life-history characteristics, distribution and refuge use does not necessarily enable successful prediction of invertebrate dispersal pathways or population structure. Dispersal among intermittent streams may be restricted to relatively short distances (km) for most invertebrate species. Thus, frequent drought refuges (perennial water) that provide strong connectivity to subpopulations through stream flow (hydrological dispersal), or continuous terrestrial vegetation (flight dispersal), will be critical to maintain genetic diversity, adaptability and population persistence.
Resumo:
El agua junto a las variaciones climáticas, encabezan discursos políticos y científicos globales en los que resurgen los debates sobre los conflictos acerca de este recurso, la geopolítica del agua, la gestión, la contaminación y la polución. Ante este panorama el IPCC (Panel Intergubernamental del Cambio Climático), la Organización Mundial de Meteorología (OMM),el Programa de la Naciones Unidas para el Medio Ambiente (PNUMA) y distintas organizaciones medioambientales hanenfocado sus intereses científicos en estudios en los cuales se utilicen indicadores hidroclimáticos. En este contexto, este artículo analiza la evolución hidroclimática reciente en dos cuencas principales de la isla de Puerto Rico, utilizando como indicadores las temperaturas, las precipitaciones y los caudales de distintas estaciones de NOAA y el USGS. Inicialmente analizamos cada estación individualmente y luego se hizo un análisis conjunto de la cuenca. Con los resultados obtenidos,en ninguna de las cuencas se pudo establecer tendencias claras en cuanto a la precipitación total anual. Aunque algunas estaciones mostraron tendencias positivas y otras regresivas, ninguna alcanzó valores estadísticamente significativos que permita rechazar la hipótesis nula de no tendencia. Nuestro análisis indica también que en una cuenca la temperatura media anual mostró un ligero aumento, mientras que en la otra la temperatura manifestó descendió. Por otro lado, el volumen de agua anual que discurre por las cuencas ha disminuido en ambos ríos donde se pudo rechazar la hipótesis nula de no tendencia con el análisis de Mann-Kendall. No obstante, existen otros factores que no fueron objeto de estudio en este análisis y que tienen impactos sobre los recursos hídricos, así como los distintos mosaicos paisajísticos que componen una cuenca hidrográfica.Palabras Claves: recursos hídricos, tendencias hidroclimáticas, cambio climático.ABSTRACTToday, water resources and climatic oscillations dominate all political and scientific discourses where the principal debate is focused on water management, water pollution and the geopolitics of this resource. Against this background, the IPCC (Intergovernmental Panel for Climate Change), WMO(World Meteorology Organization), the United Nations Environmental Program (UNEP) and other environmental organizations have focused their scientific research on hydro-climatic evolution. In this context, this article examines recent developments in hydro-climatic evolution on two mainrivers in Puerto Rico, using temperature, rainfall, stream-flow and discharge data from NOAA climatic stations and USGS hydrological stations. Initially, we analyze data from each individual station and then make an integrated analysis of the basins. With the obtained results, in none of the basins was it possible to establish clear trends as to total annual precipitation. Though some stations showed positive trends and others regressive, none reached statistically significant values.Our analysis also indicates that in one basin the annual average temperature showed a slight increase, whereas in the other basin a temperature decrease was confirmed. On the other hand, the volume of annual discharge from both rivers showed a decrease. However, there are other factors that were not considered in this analysis, such as land use, that impact water resources and the various landscape mosaics comprising a watershed.Key Words: water resources, hydro-climatic evolution, climate change
Resumo:
La visión bioregional de la conservación es reciente en Brasil. El planeamiento de mosaicos de las áreas protegidas con las intervenciones previstas en la zona tapón es un alternativa para corregir los dibujos actuales de áreas de protección. Lo Continuum Ecológico de Paranapicaba en el estado de Sâo Paulo (Brasil) se puede considerar uno de los corredores restantes más importantes de Mata Atlântica, reducidos hoy solamente a 7.3% de su extensión original. El Continuum Ecológico de Paranapiacaba tiene un alto nivel de biodiversidad. Se caracteriza por la vegetación que presenta gran diversidad estructural, y por lo tanto, así como la presencia de las especie-llaves endémicas, que requieren los esfuerzos efcientes para su conservación. Las estrategias que vienen siendo adoptados por los parceiros de la conservación buscan demostrar que es posible construir las ofertas adecuadas del uso y de la exploración sostenible de los recursos naturales. El empalme de algunas iniciativas socioambientales con el mosaico de las unidades de conservación, busca una “buena vecindad” a las unidades de la conservación que se hallan en el área-núcleo del Continuum. Palabras clave: Mata Atlântica, bosque lluvioso, buffer zone, conservación, áreas protegidas Abstract The bioregional vision of the conservation is recent in Brazil. The planning of mosaics of areas protected with interventions planned in the buffer zone is an alternative to correct the current drawings of Protecting Areas. The ecological Continuum of Paranapicaba in the State of São Paulo (Brazil) can be considered one of the most important remaining corridors of Atlantic Rainforest, today reduced only 7.3% of its original extension. High level of biodiversity is characterized by forest vegetation that presents great structural diversity, and consequently, as well as presence of endemic species-keys, that require effcient efforts for its conservation. The strategies that come being adopted for partners of the conservation search to demonstrate that it is possible to construct to adequate proposals of use and sustainable exploration of the natural resources. The joint of the some social-environmental initiatives with the mosaic of Units of Conservation, searchs to construct a “good neighborhood” to the Units of Conservation that if fnd in the area-nucleus of Continuum.Key words: Mata Atlântica, rainforest, buffer zone, conservation, áreas protegidas
