Showing papers on "Habitat destruction published in 1996"

Natural and human-induced disturbance of seagrasses

Abstract: Many natural and human-induced events create disturbances in seagrasses throughout the world, but quantifying losses of habitat is only beginning. Over the last decade, 90000 ha of seagrass loss have been documented although the actual area lost is certainly greater. Seagrasses, an assemblage of marine flowering plant species, are valuable structural and functional components of coastal ecosystems and are currently experiencing worldwide decline. This group of plants is known to support a complex trophic food web and a detritus-based food chain, as well as to provide sediment and nutrient filtration, sediment stabilization, and breeding and nursery areas for finfish and shellfish.We define disturbance, natural or human-induced, as any event that measurably alters resources available to seagrasses so that a plant response is induced that results in degradation or loss. Applying this definition, we find a common thread in many seemingly unrelated seagrass investigations. We review reports of seagrass loss from both published and ‘grey’ literature and evaluate the types of disturbances that have caused seagrass decline and disappearance. Almost certainly more seagrass has been lost globally than has been documented or even observed, but the lack of comprehensive monitoring and seagrass. mapping makes an assessment of true loss of this resource impossible to determine.Natural disturbances that are most commonly responsible for seagrass loss include hurricanes, earthquakes, disease, and grazing by herbivores. Human activities most affecting seagrasses are those which alter water quality or clarity: nutrient and sediment loading from runoff and sewage disposal, dredging and filling, pollution, upland development, and certain fishing practices. Seagrasses depend on an adequate degree of water clarity to sustain productivity in their submerged environment. Although natural events have been responsible for both large-scale and local losses of seagrass habitat, our evaluation suggests that human population expansion is now the most serious cause of seagrass habitat loss, and specifically that increasing anthropogenic inputs to the coastal oceans are primarily responsible for the world-wide decline in seagrasses.

From Individual Behaviour to Population Ecology

Abstract: Interference Depletion Prey availability Prey populations Territories Mating systems and reproductive success Population regulation Migration Applied problems Habitat loss Predator avoidance and human disturbance Modelling techniques

Using Landscape Indices to Predict Habitat Connectivity

Abstract: The ecological consequences of habitat fragmentation include the direct effects of habitat loss and the indirect effects of reduced inter-patch dispersal. In particular, habitat patches that survive the process of fragmentation become increasingly isolated from one another, and this can cause species' declines in excess of predictions based strictly on reductions in habitat area. To quantify the hindrance of dispersal caused by habitat frag- mentation, landscape ecologists have invented the notion of habitat connectivity. Indices of landscape pattern are frequently used to estimate habitat connectivity, but whether they actually do so remains undocumented. If indices of habitat pattern do indeed estimate habitat connectivity, then these indices should correlate well with predictions of dispersal success. To test this possibility, I looked for correlations between nine common indices of habitat pattern and the results of a simulated dispersal process conducted using GIS data on the distribution of old-growth forest through the Pacific Northwest. The nine indices of habitat pattern that I examined were only weakly correlated with the results from the dispersal modeling, but I identified a new pattern index, termed patch cohesion, for which the fit was much better. Moreover, I found patch cohesion to be insensitive to the details and artifacts of the dispersal model. The methodology described here will be useful to inves- tigators using indices of landscape pattern to quantify habitat fragmentation.

Habitat Fragmentation and Extinction Thresholds in Spatially Explicit Models

Abstract: The incidence of habitat destruction on the survivorship of a single metapopulation is studied by means of a spatially explicit model. As the proportion of destroyed sites increases, the structural properties of the resulting landscape change in a non-linear way, showing the existence of critical thresholds and phase transitions. Such critical thresholds are identified by means of an order parameter, which discriminates a quantitative process, i.e. habitat loss, from a qualitative one, i.e. habitat fragmentation. This difference is only well understood using a spatially explicit framework. We introduce on such a fragmented landscape the dynamics of a metapopulation balanced by local colonization and extinction by means of the cellular automaton formalism. The existence of extinction thresholds when a given fraction of habitat is destroyed is reported. These thresholds are determined both by the critical behaviour of the landscape structural properties, and by the demographic properties of the metapopulation. Some differences between these results and those derived from the study of spatially implicit models are described and explained. In particular, the percentage of patch occupancy is lower for a given value of habitat destruction in the spatially explicit formulation. Extinction threshold also take place for a lower destruction value. Some implications for the management of natural landscapes are discussed.

Control of mammalian predators in game management and conservation

Abstract: Wildlife management in modern environments has to contend with an inheritance of faunal and landscape changes caused by humans which affect the relationships between predatory and prey species. In both game management for harvesting, and in species preservation, this leads to difficult decisions about whether and how to manage predation. Predator control by humans is as old as livestock husbandry. The deliberate, often organized, destruction of many mammalian predator species has been a feature of human development in Europe - and later in countries to which Europeans spread - for centuries. Destruction to the point of extinction was practised for a number of reasons (self-protection, protection of domestic stock, protection of wild game, fur, adventure, sport) which were rarely distinguished. Reduction of predator numbers specifically to allow an increased harvest of some game species was mainly a nineteenth century development, while the adoption of predator control to benefit endangered species for their own sake belongs to recent decades. We review scientific literature relevant to predator control in game management and in conservation. Understanding of the role of predation in prey population dynamics has changed considerably during the last 20 years, and predation is now credited with a much more powerful role than in the past. Increasingly it becomes possible not merely to understand what predator control achieves, but to predict when it might be valuable in management, and what strategy will best achieve the aims. Examples of conservation problems involving predation illustrate the complexity of decision-making in management. Because of habitat loss, habitat degradation, altered predator communities, or altered predator-prey ratios, predation losses often have increased significance in modern environments. Novel approaches potentially offer non-lethal ways to manage mammalian predators. However, most are still in an exploratory phase and there have been no unqualified successes. The best tested approach, excluding predators from small areas by fencing, is discussed. In Britain, predator control to benefit small game populations and allow harvesting has been practised for nearly 200 years, and has undoubtedly played a role in shaping the present-day fauna. Although earlier gamekeeping severely reduced the geographical range of several mammalian (and avian) predator species, nowadays predator control is subject to legal restrictions based on species' conservation status and humaneness. However, illegal persecution of species protected by law remains a persistent and significant conservation problem. The predator species legitimately targeted are successful, common and increasing in the modem environment, while wild populations of gamebirds and many other ground-nesting birds are declining seriously in most areas.

Predicting the Occurrence of Endangered Species in Fragmented Landscapes

Abstract: Reliable prediction of metapopulation persistence in fragmented landscapes has become a priority in conservation biology, with ongoing destruction of habitat confining increasing numbers of species into networks of small patches. A spatially realistic metapopulation model, which includes the first-order effects of patch area and isolation on extinction and colonization, has been tested. The distribution of an endangered butterfly was successfully predicted on the basis of parameter values estimated for a well-studied congeneric species. This modeling approach can be a practical tool in the study and conservation of species in highly fragmented landscapes.

Thermal Limits to Salmonid Distributions in the Rocky Mountain Region and Potential Habitat Loss Due to Global Warming: A Geographic Information System (GIS) Approach

Abstract: The present distribution of salmonid fishes in Wyoming streams was found to be limited to regions where mean July air temperatures did not exceed 22°C. Much of the present salmonid habitat in streams is predicted to be lost if climatic warming occurs. For increases of 1, 2, 3, 4, or 5°C in mean July air temperature, the geographic area of Wyoming containing suitable salmonid habitat would be reduced by 16.2, 29.1, 38.5, 53.3, or 68.0%, respectively. This loss of geographic range would correspond to reductions of 7.5, 13.6, 21.0, 31.4, or 43.3% in the length of streams having suitable salmonid habitat. In the Rocky Mountain region, increases of 1, 2, 3, 4, or 5°C in mean July air temperature would reduce the geographic area containing suitable salmonid habitat by 16.8, 35.6, 49.8, 62.0, or 71.8%, respectively. As warming proceeds, salmonid populations would be forced into increasingly higher elevations and would become fragmented as suitable habitat for coldwater fish becomes separated from main r...

Potential habitat loss and population fragmentation for cold water fish in the North Platte River drainage of the Rocky Mountains : Response to climate warming

Abstract: We used three approaches to examine potential habitat loss in relation to climate warming for cold water species of fish in the North Platte River drainage in Wyoming. The projected loss of habitat varied among approaches, but all methods indicated a noticeable loss of habitat for even minor increases in temperature. An approach based on the use of summer air temperatures to define the thermal limits of cold water species estimated a loss of 9-76% of the present geographic range for temperature increases of 1-5°C. A second approach, also based on air temperature limits, projected a loss of 7-64% of the stream distance currently having thermally suitable habitat for cold water fish for temperature increases of 1-5°C. A third approach, based on the use of summer water temperatures to define the thermal limits of cold water species, projected a loss of 16-69% of the stream distance currently having thermally suitable habitat for temperature increases of 1-5°C. In addition to habitat loss, population fragmentation would occur as remaining enclaves of cold water fish are forced to retreat to increasingly isolated headwater stream reaches.

Management Strategies to Conserve Marine Biodiversity

Abstract: INTRODUCTION Biodiversity is the variety of living organisms and their habitats: the structure, composition, dynamics, and function of living systems acquired over millions of years of evolution. Marine biodiversity is extremely rich but is poorly understood and has only recently become the subject of conservation concerns (Norse, 1993). Biodiversity refers to the spatial organization of plants and animals in a hierarch at the genetic, organism, population, species, community, ecosystem, and seascape levels (Hughes and Noss, 1992; Norse, 1993). Major threats to biodiversity are habitat destruction, environmental changes, and overfishing (Upton, 1992). Losses of biodiversity at the genetic and species levels are of special concern because they are permanent.

Habitat alteration, hunting and the conservation of folivorous primates in African forests

Abstract: The colobus monkeys and gorillas of African forests share a strong tendency to depend on foliage during lean seasons. In many areas, both kinds of primate are threatened by habitat destruction. But while the total removal of natural habitat is clearly a major threat to the survival of many African forest primates, an analysis of survey data suggests that human predation tends to have a greater negative impact on primate populations than does selective logging or low-intensity bush-fallow agriculture. In the absence of hunting, the population density of colobus monkeys correlates with the protein: fibre ratio of mature tree foliage in their habitat, and the density of gorillas appears to be correlated with the abundance of terrestrial herbaceous vegetation. Because moderately disturbed forest can be relatively rich in high-quality lean-season folivore foods, such forest sometimes supports a higher density of folivorous primates than forest that has not been recently disturbed but that has been subject to hunting. Conservation plans for African forests should place more emphasis on the control of hunting and less on rural development, and long-range plans should also allow for the strong possibility of political instability.

Population responses to habitat fragmentation: statistical power and the random sample hypothesis

Abstract: Oikos 76: 235-242. The random sample hypothesis states that small habitat fragments are random samples from large ones. Therefore, the effect of habitat fragmentation on population size is only related to pure habitat loss, the area and isolation of habitat fragments do not influence the population size in the landscape. An alternative hypothesis is that probability of occupation of a habitat fragment is related to area and isolation of the habitat fragment. Simulation models that included effects of area and isolation were used to investigate the effect of habitat fragmentation on population survival in landscapes with different proportions of suitable habitat. Four different combinations of area sensitivity and dispersal ability were used. These models were used to estimate the statistical power to reject the random sample hypothesis. The statistical power to detect differences, between a model based on the random sample hypothesis and a model which included effects of habitat fragment size and isolation between habitat fragments on population survival, was low in landscapes with a high proportion of suitable habitat, but increased as the proportion of suitable habitat decreased. Therefore, the results of different tests that support or reject the random sample hypothesis might be due to differences in the proportion of suitable habitat in the landscape. In landscapes where there are no effects of fragment size and isolation the habitat is functionally still continuous and the two hypotheses will give very similar predictions about the effects of habitat fragmentation. The threshold value in proportion of suitable habitat in the landscape where there is a true effect of habitat fragmentation (threshold for fragmentation) will vary across species and landscapes. H.

Predicting the Consequences of Habitat Loss for Migratory Populations

Abstract: For many migratory species the area of wintering or breeding habitat is changing or is likely to change as a result of processes such as habitat destruction or global environmental change. I show that the ratio of population decline to loss of typical wintering habitat equals d9/(d9 + b9), where d9 is the slope of relation between per capita winter mortality and population density and b9 is the slope of the relation between per capita net breeding output and population density. Similarly the ratio of population decline to loss of typical breeding habitat equals b9/(b9 + d9). Game theory models can be used to predict the values of b9 and d9. For example, incorporating values of d9 and b9 from such models for the oystercatcher Haematopus ostralegus shows that a loss of 1% of wintering habitat will result in a population decline of 0.69% while a loss of 1% of breeding habitat will result in a population decline of 0.31%.

Species Richness of Reef-Building Corals Determined by Local and Regional Processes

Abstract: Species richness in ecological communities has traditionally been explained in terms of species interactions, especially competition, operating within the local community over relatively short periods of time. Recently, it has become clear that ecological communities can be organized by a variety of processes operating at different spatial and temporal scales. Since local communities are imbedded within larger geographic regions, regional/historical phenomena and local processes may influence local richness jointly and should be analysed simultaneously. Here we perform such an analysis by comparing assemblages of hermatypic scleractinian corals from different regions sampled at over 100 sites around the world. Using multiple regression analysis, we find that local richness is as sensitive to regional richness as it is to each of two variables (depth and habitat) that subsume much of the local variability at a site. Our results indicate that although coral assemblages are believed to be intensely interactive, they are, nevertheless, regionally enriched and show no evidence of saturation. Multi-scale effects on local richness demand further investigation to clarify causal relationships, and to enlighten policy decisions over issues of biodiversity, habitat loss and fragmentation, and ecological restoration.

Global change and coral reefs: impacts on reefs, economies and human cultures

Abstract: Coral reefs have reconstituted themselves after previous large sea-level variations, and climate changes. For the past 6000 years of unusually stable sea-level, reefs have grown without serious interruptions. During recent decades, however, new stresses threaten localized devastation of many reefs. A new period of global climate change is occurring, stimulated by anthropogenic increases in greenhouse gases. Coral reefs will cope well with predicted sea-level rises of 4.5 cm per decade, but reef islands will not. Higher sea levels will provide corals with greater room for growth across reef flats, but there are no foreseeable mechanisms for reef island growth to keep pace with sea-level rise, therefore many low islands may ultimately become uninhabitable. Climate change will introduce localized variations in weather patterns, but changes to individual reefs cannot be predicted. Reefs on average should cope well with regional climate change, as they have coped with similar previous fluctuations. Air temperature increases of 0.2-0.3 °C/decade will induce slower increases in sea-surface temperatures, which may cause localized, or regional increases in coral bleaching. Changes in rainfall will impact on reefs near land masses. Likewise, increased storms and variations in El Nifio Southern Oscillation (ENSO) may stress some reefs, but not others. The greatest impact of climate change will be a synergistic enhancement of direct anthropogenic stresses (excessive sediment and pollution from the land; over-fishing, especially via destructive methods; mining of coral rock and sand; and engineering modifications), which currently cause most damage to coral reefs. Many of the world's reefs have been degraded and more will be damaged as anthropogenic impacts increase under the 'demophoric' increases in population (demos) and economic (phoric) activity. This biotic and habitat loss will result in severe economic and social losses. Reefs, however, have considerable recovery powers and losses can be minimized by effective management of direct human impacts and reducing indirect threats of global climate change.

British columbia lake enrichment programme: two decades of habitat enhancement for sockeye salmon

Abstract: The anadromous sockeye salmon (Oncorhynchus nerka) is the most valuable salmonid species on the Pacific coast of North America. Juvenile sockeye rear for 1–2 years in lakes, where they feed primarily on crustacean zooplankton. As a result of overfishing and habitat loss for over a century, most British Columbia nursery lakes are now recruitment limited, with too few adult salmon returning to spawn and provide fry. However, declining adult escapements have also resulted in a significant loss of nitrogen (N) and phosphorus (P) nutrients supplied by decomposing adult carcasses and the lakes have become less productive (oligotrophication) for rearing sockeye fry. To reverse this process and increase sockeye salmon abundance, in 1976 the Canadian Department of Fisheries and Oceans began enriching nursery lakes with nitrogen and phosphorus nutrients to increase their productivity and fry-rearing capacity. Many of the objectives, techniques and results from the Lake Enrichment Programme are also applicable to the management of regulated watersheds where mitigation for possible long-term reductions in freshwater habitat productivity is a concern. Over the last two decades, 20 lakes were fertilized weekly through the growing season with liquid fertilizers. The lakes have received limnological and fisheries assessments that have focused on pelagic food-webs and production processes. The lakes have shown a positive response at all trophic levels to nutrient additions, with an increase in activity and doubling of bacteria abundance, increases of 50–60% in autotrophic picoplankton abundance and phytoplankton biomass (chlorophyll) and up to twofold increases in primary production and zooplankton biomass. This enhanced lake production has increased growth and survival of juvenile sockeye and increased smolt weights (>60%) resulting in larger sockeye adult returns worth 10–20 million dollars per year to the Canadian economy. The benefit : cost ratio of lake fertilization is the best of currently available salmonid enhancement techniques.

An investigation on fire effects within xeric sage grouse brood habitat.

Abstract: We investigated the short-term influence of fire on xeric sage grouse (Centrocercus urophasianus) brood habitat in southeastern Idaho from 1990-92. A prescribed fire in 1989 removed Wyoming big sagebrush (Artemisia tridentata wyomingensis Nutt.)/threetip sagebrush (A. tripartita Rydb.) canopy cover from approximately 57% of a 5,800-ha area, potentially influencing brood-rearing habitat. Although the fire created a mosaic of sagebrush areas interspersed with open areas having abundant grasses and forbs, the relative abundance of males, females, and broods on survey routes in burned and unburned habitat were similar. Cover of forbs important in sage grouse summer diets was similar in burned and unburned habitat. However, the abundance of Hymenoptera, an insect Order important in sage grouse diets, was significantly lower in burned habitat the second and third years postburn. Our research did not support the contention that fire may enhance sage grouse brood-rearing habitat.

Habitat Destruction and the Extinction Debt Revisited

Abstract: A very important published analysis of the problem of habitat destruction (Tilman et al. 1994 (Nature 371:65-66)) concluded that such destruction may lead to an extinction debt, which is the irreversible, preferential loss of competitive species following a prolonged transient or delay after the habitat destruction. We analyzed this model using analytic and simulation techniques. Relating this analytic model to real-world situations shows that it applies to scattered permanent devegetation of small patches and to across- the-board decreases in fecundity such as could be caused by pollution. For repeated spatially random disturbance, we develop a new model that shows an even more severe extinction- debt effect. For larger fragments of remnant vegetation, such as forest woodlots, we argue that the assumptions of the model are violated but that an extinction debt nevertheless occurs due to gradual stochastic elimination of species that are very rare and isolated in these fragments. For habitat destruction on regional scales (reduction in ecosystem area without disturbance in remnant areas), one must, in contrast, apply species-area relations based on the distribution of different habitat types (e.g., elevational and rainfall gradients; physiographic and edaphic variability). Such an analysis predicts rapid, not delayed, loss of all types of species, not just competitive types. We conclude that the extinction-debt effect is real and arises in three different models, but relating the models to real-world conservation problems must be done with care.

Linking Extinction to Connectivity and Habitat Destruction in Metapopulation Models

Abstract: A metapopulation is a set of populations distributed over a number of patches that are connected, to varying degrees, by dispersal movements (e.g., Levins 1969, 1970; Hanski 1989; Hanski and Gilpin 1991). Single-species metapopulation models focus on the balance between recolonization and local extinction, with metapopulation persistence possible only if the rate at which empty patches are recolonized exceeds the rate at which populations go extinct (Hanski 1991). Conservation biologists have used metapopulation theory to support conservation corridors and other management techniques that create metapopulations. By enhancing the ability of individuals to move among populations, corridors are intended to increase the rate at which locally extinct patches are recolonized (e.g., Mackintosh 1989; Hudson 1991; Saunders and Hobbs 1991; Noss 1992). A metapopulation is also created when people move individuals in captive and managed wild populations among populations to maintain genetic diversity, replenish depleted populations, and establish populations in new areas (e.g., Cade 1988; Griffith et al. 1989; Rahbek 1993). In the absence of empirical data demonstrating that increasing migration rates increases the chance of metapopulation persistence-indeed, examples of metapopulations in nature have been hard to find (Taylor 1991; Harrison 1994)models have played a pivotal role in supporting initiatives that would create metapopulations. The single-species metapopulation model introduced by Levins (1969) has become the centerpiece of the metapopulation paradigm in conservation biology. This in itself is somewhat ironic because Levins was investigating methods to increase the regional effectiveness of crop pest control. In other words, he was trying to figure out how to increase extinctions. His model, expressed in its familiar form, is

Decline of Some West-Central Florida Anuran Populations in Response to Habitat Degradation

Abstract: Recent reports have suggested that a global decline in amphibian populations has taken place during the past few decades. Urban development is thought to affect the richness and abundances of species and, therefore, could be an important cause of decline. We estimated the richness and abundances of anurans in wetlands at a residential development and in similar wetlands at a nearby undeveloped park. The residential development originally was pine flatwoods habitat, as is the undeveloped park curiently. We also compared the anuran species' composition of the park in 1992 with the composition in 1974. Both richness and abundances of anurans in the residential development were different than those in the undeveloped park. Employing the same amount of sampling effort at both sites, we trapped or observed 11 species at the developement and 15 species at the park, and trapped 569 individuals at the development and 1224 individuals at the park. The anuran species richness at the undeveloped park in 1992 was nearly the same as in 1974; a single rare species apparently was not present in 1992. Of the 15 species present in both surveys, 14 showed higher abundances in 1992 than in 1974. We suggest that the current differences between the residential development and the park have resulted from degradation of both the uplands used by many species during the dry season and the temporary wetlands used by many species for reproduction. Four species especially sensitive to such degradation, Bufo quercicus, Scaphiopus h. holbrookii, Hyla femoralis, and H. gratiosa, were the species missing from the residential development. Not all species of anurans typical of pine flatwoods appeared to be affected adversely by development. Three species of ranids, Rana utricularia, R. grylio, and R. catesbeiana, were found in higher abundances at the residential development than at the park. These ranid species breed in a wide variety of aquatic systems, including the permanent bodies of water that are now abundant in the development, and probably use the uplands less than other anurans. If amphibian decline is international in scope, then the decline could be attributable either to global changes caused by humans, or to local, but widespread, environmental degradation, or to a combination of factors. While much recent popular focus has been on potential global causes of decline, we believe that this emphasis may have caused attention to be taken away from local causes that, as our study demonstrated, may be at least as important. We suggest that in many places, local environmental degradation is insidiously chipping away at amphibian diversity, and that more emphasis should be placed on these local causes than is now the case.

Geostatistics as a tool for examining hypothesized declines in migratory songbirds

Abstract: Data from the North American Breeding Bird Survey (BBS) indicate sig- nificant declines in the populations of several species of songbirds, including several Neo- tropical migrants. These declines have been attributed to habitat destruction and fragmen- tation on the breeding grounds, in strategic migratory stopover sites, and on the wintering grounds. Using BBS data from the 1967-1989 period and universal kriging, we produced maps of abundance change for two declining species of wood warblers to test hypothetical spatial scenarios of decline over entire breeding ranges. These species were the Cerulean Warbler (Dendroica cerulea) and the Prairie Warbler (D. discolor). We found considerable variability in the location of areas of decline when comparing successive 5-yr periods. In some comparisons, areas of decline were concentrated in the centers of abundance of these species, and in others, they were scattered throughout their range. We also found that the direction and intensity of population trends was quite sensitive to the methods used for calculating abundance. Our results indicate that, even for species where significant long- term declines have been reported, considerable variation exists in the direction of abundance change, both geographically and temporally. Although most of the long-term declines re- ported in particular species at local and regional scales are undeniable, gaps in our knowl- edge still prevent us from incorporating these trends into a global model of the annual cycle of Neotropical migrants.

Processes of wetland loss in India

Abstract: Wetlands in India supply crucial human and animal needs such as drinking water, protein production, fodder, water purification, wildlife habitat, and flood storage. Increased appreciation of uses and threats is essential to protect wetlands where justified. Three quarters of India's population is rural, it places great demands on India's wetlands and losses continue to occur. This paper is based on extensive discussions with natural resource managers, government employees, farmers, academicians, and resource users at dozens of sites in India, as well as an extensive literature search. Twelve important kinds of wetland loss are identified and mechanisms believed to be causing them discussed: (1) agricultural conversion, (2) direct deforestation, (3) hydrologie alteration, (4) inundation, (5) defoliation, (6) altered upper watersheds, (7) accumulative water demands, (8) water quality degradation, (9) wetland consolidation, (10) global climate change, (11) ground-water depletion, (12) exotic species and biodiversity. Wetland understanding, management, and Public awareness in India must continue growing if wetland resources are to remain functional.

The decline of the Green and Golden Bell Frog Litoria aurea viewed in the context of declines and disappearances of other Australian frogs

Abstract: The Green and Golden Bell Frog Litoria aurea has undergone a reduction in range and significant population declines during the past 15 years. In this paper the decline is viewed from the perspective of declines and disappearances of other species of frog along the east coast of Australia. In contrast to L. aurea most declines affected species occurring at high altitude with relatively restricted ranges. These species typically bred in streams, adults were closely associated with stream habitats, and anthropogenic impacts such as habitat destruction, pollution or introduced predators have not been identified. The decline of the Green and Golden Bell Frog accords in part with this pattern, high altitude populations have disappeared and low altitude populations have declined. However, the habitat of adults and breeding sites are typically associated with ponds and swamps not streams. Because the causal agent responsible for declines has not been identified, an experimental approach is considered to be necess...

The mountain tapir, endangered ‘flagship’ species of the high Andes

Abstract: The mountain tapir has already disappeared from parts of its range in the high Andes of South America and remaining populations are severely threatened by hunting and habitat destruction. With an estimated population of fewer than 2500 individuals, urgent measures are necessary to secure a future for the species. This paper presents an overview of the species throughout its range as well as some of the main results of the author's studies on tapir ecology. Finally, a plea is made for conservation action in Sangay National Park, which is one of the species's main strongholds.

Coasts in Crisis

Abstract: Coastal areas are staggering under an onslaught of human activity. We are presently in the process of destroying 70 percent of the world`s 600,000 square kilometers of coral reefs, an ecosystem containing some 200,000 different species and rivaling tropical rain forests in biodiversity. A combination of pollution, habitat destruction, and gross overfishing has led to the collapse of major fisheries and paved the way for malnutrition and disease in regions where people fish for subsistence. Globally, little is being done to manage the crisis of our coasts. Management strategies, if they exist at all, often deal with economic development along a wafer-thin strip of coastal land. Resource degradation is ignored, and watershed management is mostly rhetoric. Although some 55 countries have drawn up coastal management plans, only a handful have been properly implemented. Coasts must be managed in an integrated manner that takes into account the full range of human activities. Initiating this process is costly, time-consuming, and difficult. Yet we have more than three decades of accumulated experience to draw on.