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Key Habitats (key + habitat)
Selected AbstractsPotential impacts of projected sea-level rise on sea turtle rookeriesAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 2 2010MMPB Fuentes Abstract 1.Projected sea-level rise (SLR) is expected to cause shoreline erosion, saline intrusion into the water table and inundation and flooding of beaches and coastal areas. Areas most vulnerable to these physical impacts include small, tropical low-lying islands, which are often key habitat for threatened and endemic species, such as sea turtles. 2.Successful conservation of threatened species relies upon the ability of managers to understand current threats and to quantify and mitigate future threats to these species. This study investigated how sea-level rise might affect key rookeries (nesting grounds) (n=8) for the northern Great Barrier Reef (nGBR) green turtle population, the largest green turtle population in the world. 3.3-D elevation models were developed and applied to three SLR scenarios projected by the IPCC 2007 and an additional scenario that incorporates ice melting. Results indicate that up to 38% of available nesting area across all the rookeries may be inundated as a result of SLR. 4.Flooding, as a result of higher wave run-up during storms, will increase egg mortality at these rookeries affecting the overall reproductive success of the nGBR green turtle population. Information provided will aid managers to prioritize conservation efforts and to use realistic measures to mitigate potential SLR threats to the nGBR green turtle population. Copyright © 2009 John Wiley & Sons, Ltd. [source] North American Brant: effects of changes in habitat and climate on population dynamicsGLOBAL CHANGE BIOLOGY, Issue 6 2005David H. Ward Abstract We describe the importance of key habitats used by four nesting populations of nearctic brant (Branta bernicla) and discuss the potential relationship between changes in these habitats and population dynamics of brant. Nearctic brant, in contrast to most geese, rely on marine habitats and native intertidal plants during the non-breeding season, particularly the seagrass, Zostera, and the macroalgae, Ulva. Atlantic and Eastern High Arctic brant have experienced the greatest degradation of their winter habitats (northeastern United States and Ireland, respectively) and have also shown the most plasticity in feeding behavior. Black and Western High Arctic brant of the Pacific Flyway are the most dependent on Zostera, and are undergoing a shift in winter distribution that is likely related to climate change and its associated effects on Zostera dynamics. Variation in breeding propensity of Black Brant associated with winter location and climate strongly suggests that food abundance on the wintering grounds directly affects reproductive performance in these geese. In summer, salt marshes, especially those containing Carex and Puccinellia, are key habitats for raising young, while lake shorelines with fine freshwater grasses and sedges are important for molting birds. Availability and abundance of salt marshes has a direct effect on growth and recruitment of goslings and ultimately, plays an important role in regulating size of local brant populations. [source] Habitat-specific demography and source,sink dynamics in a population of Siberian jaysJOURNAL OF ANIMAL ECOLOGY, Issue 1 2010Magdalena Nystrand Summary 1.,There are a number of models describing population structure, many of which have the capacity to incorporate spatial habitat effects. One such model is the source,sink model, that describes a system where some habitats have a natality that is higher than mortality (source) and others have a mortality that exceeds natality (sink). A source can be maintained in the absence of migration, whereas a sink will go extinct. 2.,However, the interaction between population dynamics and habitat quality is complex, and concerns have been raised about the validity of published empirical studies addressing source,sink dynamics. In particular, some of these studies fail to provide data on survival, a significant component in disentangling a sink from a low quality source. Moreover, failing to account for a density-dependent increase in mortality, or decrease in fecundity, can result in a territory being falsely assigned as a sink, when in fact, this density-dependent suppression only decreases the population size to a lower level, hence indicating a ,pseudo-sink'. 3.,In this study, we investigate a long-term data set for key components of territory-specific demography (mortality and reproduction) and their relationship to habitat characteristics in the territorial, group-living Siberian jay (Perisoreus infaustus). We also assess territory-specific population growth rates (r), to test whether spatial population dynamics are consistent with the ideas of source,sink dynamics. 4.,Although average mortality did not differ between sexes, habitat-specific mortality did. Female mortality was higher in older forests, a pattern not observed in males. Male mortality only increased with an increasing amount of open areas. Moreover, reproductive success was higher further away from human settlement, indicating a strong effect of human-associated nest predators. 5.,Averaged over all years, 76% of the territories were sources. These territories generally consisted of less open areas, and were located further away from human settlement. 6.,The source,sink model provides a tool for modelling demography in distinct habitat patches of different quality, which can aid in identifying key habitats within the landscape, and thus, reduce the risk of implementing unsound management decisions. [source] Priority habitats for the conservation of large river fish in the Ganges river basinAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 4 2007Uttam Kumar Sarkar Abstract 1.Three classes of habitat used by groups of fish species classified as conservation and management priorities were developed for the Gerua River (also known as the Girwa River, Karnali River) in the Ganges river basin. This river is large (mean annual discharge ca 1500 m3 s,1, up to 900 m wide), surrounded by protected lands of India and Nepal, and upstream of major diversions and river alterations. 2.Fish and habitat sampling was conducted at 45 sites from 2000 to 2003. Data were analysed for 2172 fish of 14 species. Species and life stages found occupying a statistically distinct subset of the river habitats were grouped to identify classes of river habitat for conservation. 3.Most species and life-stage groups specialized on specific habitat conditions revealed by multivariate analyses of variance and a principal component analysis. The most numerous and diverse group (six species, 15 life stages) was associated with deep depositional habitats with sandy substrate. Two species covering three life stages were primarily oriented to erosional habitat marked by fast current velocity with pebble and cobble substrate. A third group of three species of adults and juveniles were intermediate in habitat use. 4.River conservation for fish faunas should maintain both erosional and depositional channel habitats with depths, substrates, and current velocity inclusive of the ranges reported. The erosional and depositional nature of the key habitats requires that rivers be maintained with flows capable of channel-forming functions. Copyright © 2006 John Wiley & Sons, Ltd. [source] | ||||||||||