845 resultados para Conservation of biodiversity


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The Danube is ca. 2850 km in length and is the second largest river in Europe. The Austrian part of the Danube falls 156 metres in altitude over its 351 km length and, since the early 1950s, the river has been developed into a power-generating waterway, so that the continuity of the river is now interrupted by ten impounded areas. Only two stretches of the original free-flowing river are left, the Wachau region (above river-km 2005, west of Vienna) and the region downstream from the impoundment at Vienna (river-km 1921). Most of the recent theories and concepts related to invertebrates, in the context of the ecology of running waters, are based on studies on small streams, whereas investigations of large rivers have played a minor role for a long time, mainly due to methodological difficulties. The authors' recent detailed studies on macroinvertebrates in the free-flowing section of the Danube below Vienna, provide an excellent opportunity to survey or restate scientific hypotheses on the basis of a large river. In this review the main interest focuses on the investigation of biodiversity, i.e. the number of species and their relative proportions in the whole invertebrate community, as well as major governing environmental factors. The article summarises the species composition, the important environmental variables at the river cross-section and the effect of upstream impoundment on the riverbed and its fauna.

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There are many ways of practising freshwater nature conservation: from strict legislative protection of individual species considered rare or threatened to protecting whole lakes or long stretches of rivers; from practical conservation management at a local scale to integrated catchment management at the river basin scale; and from the encouragement of better habitat management through codes of good practice to statutory control of pollution or abstraction. Whatever the mechanism, an essential pre-requisite is a way of choosing where to put the effort, especially when resources for nature conservation are severely limited. The aim of this article is to review the contribution from four specific international measures to the task of assigning priorities for conservation. The 1990s saw the introduction of two European directives (the Habitats Directive (HD) and the Water Framework Directive (WFD)) and one international convention (the Biodiversity Convention (CBD)) each with the potential for influencing, to a greater or lesser extent, the conservation of freshwater habitats and species. This article also discusses a much older convention – the Ramsar Convention – adopted in 1971 specifically to help tackle the conservation and management of wetlands and aquatic ecosystems. Although the authors have focused mainly on the UK, the subject is relevant to other parts of Europe and beyond. The article explores the degree to which these measures help in identifying the most important fresh waters for conservation, and asks whether or not they present the right conservation message to a wide audience.

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For efficient use of conservation resources it is important to determine how species diversity changes across spatial scales. In many poorly known species groups little is known about at which spatial scales the conservation efforts should be focused. Here we examined how the community turnover of wood-inhabiting fungi is realised at three hierarchical levels, and how much of community variation is explained by variation in resource composition and spatial proximity. The hierarchical study design consisted of management type (fixed factor), forest site (random factor, nested within management type) and study plots (randomly placed plots within each study site). To examine how species richness varied across the three hierarchical scales, randomized species accumulation curves and additive partitioning of species richness were applied. To analyse variation in wood-inhabiting species and dead wood composition at each scale, linear and Permanova modelling approaches were used. Wood-inhabiting fungal communities were dominated by rare and infrequent species. The similarity of fungal communities was higher within sites and within management categories than among sites or between the two management categories, and it decreased with increasing distance among the sampling plots and with decreasing similarity of dead wood resources. However, only a small part of community variation could be explained by these factors. The species present in managed forests were in a large extent a subset of those species present in natural forests. Our results suggest that in particular the protection of rare species requires a large total area. As managed forests have only little additional value complementing the diversity of natural forests, the conservation of natural forests is the key to ecologically effective conservation. As the dissimilarity of fungal communities increases with distance, the conserved natural forest sites should be broadly distributed in space, yet the individual conserved areas should be large enough to ensure local persistence.

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Local communities and local government units are recognized as the primary stakeholders and participants in the management of coral reef resources and the primary beneficiaries of small-scale fishing activities in the nearshore areas of the coastal zone. The issues relating to the management of the coastal zone are multi-faceted and some issues are largely intertwined with national policy and development goals. Thus, national governments have jurisdiction over these nearshore coastal resources to harmonize policies, monitor resource use and provide incentives for sustainable use. However, the natural boundaries of these reef resources, the processes that support reef ecosystems, and the local or national affiliation of the people who benefit from them may transcend the boundaries of the local and national management units. Therefore, efforts to arrest the decline in fish catch and loss of biodiversity for reefs require management interventions and assessment activities to be carried out at varying scales. In Southeast Asia, some aspects of reef and reef resources management — particularly in deciding the allocation of catch among competing fisheries, development of sustainable harvest strategies, use of broodstock for restocking or stock enhancement programs, protection of nursery and spawning areas, designation of systems of marine protected areas, and the identification of representative, adequate and comprehensive areas for biodiversity conservation in the region — may require the definition of larger management units. At the regional level, multi-country initiatives will need to define units for the transboundary management of resources. The use of large marine ecosystems (LMEs) to identify and manage fisheries resources may be a starting point; however, given the relatively sedentary nature of coral reef-dwelling and reef-associated organisms compared with other pelagic and demersal species, meso-scale transboundary units within the LMEs have to be defined. This paper provides suggestions for transboundary management units for coral reef and reef-associated resources in Southeast Asia based on information from genetic structures of model organisms in the region. In addition, specific reef areas are identified, which may be important beyond their national boundaries, as potential sources of recruits.

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The highly productive fisheries of Kerala, India, are suffering from overexploitation. Use of unsuitable fishing gears that result in a high level of wasteful bycatch and destruction of egg bearing and juvenile fish should be controlled. This paper makes some suggestions for monitoring and conservation of the fisheries in Kerala.

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Two new populations and the host plant of the rarely encountered Galapagos endemic moth Epiplema becki were found on Isabela Island, on Wolf and Sierra Negra volcanoes, with a sighting on Darwin Volcano. The host plant is the native Duranta dombeyana (Verbenaceae). The habitats where all known specimens were collected were Scalesia forest with Duranta bushes. To ensure the conservation of E. becki, we recommend control of introduced species in its habitat. CDF Contribution Number 1010.

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As the earth’s resources continue to face increasing pressure from a variety of human and natural causes, protection of the environment and biodiversity is a matter of contemporary concern, The conservation of coastal and marine resources, in particular, has become a priority for countries around the world. In this context, marine protected areas (MPAs) are being widely promoted as one of the most effective tools for the conservation of coastal and marine resources. Most MPAs are located in coastal areas of great biodiversity, and hence their development has direct impacts on the lives and livelihoods of coastal communities, especially small-scale and traditional fishing communities. Typically, they are the ones who have to bear the costs of conservation practices–lost livelihood options, expulsion from traditional fishing grounds and living spaces, and violation of human/community rights, to name a few. The articles in this dossier, drawn chronologically from the pages of Samudra Report, the triannual publication of ICSF, draw attention to these issues. They show that conservation and livelihoods are closely intertwined, and that top-down, non-participatory models of conservation can be counter-productive. Despite being poor and powerless, fishing and coastal communities can be powerful allies in conservation efforts, given their longstanding dependence on natural resources and their traditional ecological knowledge systems. As the examples in this dossier reveal, it is possible for fishing communities to protect and conserve the environment, while continuing with sustainable fishing operations. Clearly, only an integrated approach to fisheries management and conservation will prove successful. This dossier will be useful for policymakers, social scientists, non-governmental organizations and others interested in fisheries, conservation, communities and livelihoods.

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Seagrass ecosystems are protected under the federal "no-net-loss" policy for wetlands and form one of the most productive plant communities on the planet, performing important ecological functions. Seagrass beds have been recognized as a valuable resource critical to the health and function of coastal waters. Greater awareness and public education, however, is essential for conservation of this resource. Tremendous losses of this habitat have occurred as a result of development within the coastal zone. Disturbances usually kill seagrasses rapidly, and recovery is often comparatively slow. Mitigation to compensate for destruction of existing habitat usually follows when the agent of loss and responsible party are known. Compensation assumes that ecosystems can be made to order and, in essence, trades existing functional habitat for the promise of replacement habitat. While ~lant ingse agrass is not technically complex, there is no easy way to meet the goal of maintaining or increasing seagrass acreage. Rather, the entire process of planning, planting and monitoring requires attention to detail and does not lend itself to oversimplification.

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Range overlap patterns were observed in a dataset of 10,446 expert-derived marine species distribution maps, including 8,295 coastal fishes, 1,212 invertebrates (crustaceans and molluscs), 820 reef-building corals, 50 seagrasses and 69 mangroves. Distributions of tropical Indo-Pacific shore fishes revealed a concentration of species richness in the northern apex and central region of the Coral Triangle epicenter of marine biodiversity. This pattern was supported by distributions of invertebrates and habitat-forming primary producers. Habitat availability, heterogeneity and sea surface temperatures were highly correlated with species richness across spatial grains ranging from 23,000 to 5,100,000 km2 with and without correction for autocorrelation. The consistent retention of habitat variables in our predictive models supports the area of refuge hypothesis which posits reduced extinction rates in the Coral Triangle. This does not preclude support for a center of origin hypothesis that suggests increased speciation in the region may contribute to species richness. In addition, consistent retention of sea surface temperatures in models suggests that available kinetic energy may also be an important factor in shaping patterns of marine species richness. Kinetic energy may hasten rates of both extinction and speciation. The position of the Indo-Pacific Warm Pool to the east of the Coral Triangle in central Oceania and a pattern of increasing species richness from this region into the central and northern parts of the Coral Triangle suggests peripheral speciation with enhanced survival in the cooler parts of the Coral Triangle that also have highly concentrated available habitat. These results indicate that conservation of habitat availability and heterogeneity is important to reduce extinction and that changes in sea surface temperatures may influence the evolutionary potential of the region.

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Trainers from the region contributed theory and practical training to trainees from government departments, universities and NGOs relevant to conservation of seagrasses and monitoring methods.

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Unlike Lake Victoria, the fisheries of Lake George have undergone gradual changes in the size and proportion of the major commercial fish species, the Nile tilapia (Oreochromis niloticus: cichlidae) in the last 40 years (1950-1989). The size decreased from an average weight of 900g in 1950 to 430g in 1989 while percentage contribution in commercial catches during the same period declined from 92% to 36%. The over all annual commercial catches though showed a steady increase from the period 1950 when the fishery was opened to intensive and controlled exploitation, consistently high catches were observed in the 1960s and 1970s followed by a general decline in the early 1980s to amore or less stable fishery in the late 1980s. These changes are attributed to increased fishing pressure especially on the nil tilapia and to increased use of smaller gill net mesh sizes lower than the recommended 127mm mesh. The changes in gill net mesh have brought O. leucostictus, acichlid, into commercial catches confirming that the 88.9mm mesh size nets are used by the commercial fishermen to harvest smaller fish species. The commercial catches are presently dominated by the piscivorous fishes,(over 60%) whose contribution was less than 10% during initial exploitation of the virgin fishery in 1950.The piscivorous fish are mainly caught using hooks and lines. The entire fishery is believed to be exploited close to the maximum. The above trends serve to show the impact of exploitation on fish species diversity. Quantitive and qualitative changes of the major fish species on lake George are due to exploitation pressure unlike Lake Victoria where it is a combination of both exploitations and impact of fish introductions. There has been no fish introduction in Lake George.

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Ancherythroculter nigrocauda is a cyprinid fish endemic to the upper reaches of the Yangtze River, which has been reported to have 2 or 3 chambers to its air bladder. Morphological studies showed no differences between individuals with different types of air bladder, but did demonstrate geographical differences from different sources. After the completion of the Three Gorges Dam, it was expected that the population of this species would decrease, but artificial breeding and stocking is under consideration to protect this species from extinction. In the present study, mtDNA cytochrome b gene sequences were determined and analyzed for A. nigrocauda samples of different morphotypes and sources to identify their genetic differentiations, and thereby guide plans for the artificial propagation and conservation of this species. Haplotype diversity index values (h) and nucleotide diversity values (pi) for all the populations were found to be high indicating their high level genetic diversity. An analysis of molecular variance identified no differentiation among the studied populations. Therefore, we suggested that the individuals of different morphological types and geographical sources belong to the same species. To maintain its high level genetic diversity, it mill he necessary to use large and diverse sources of parental fish for artificial reproduction.

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Understanding the population genetic structure is a prerequisite for conservation of a species. The degree of genetic variability characteristic of the mitochondrial DNA control region has been widely exploited in studies of population genetic structure and can be useful in identifying meaningful population subdivisions. To estimate the genetic profile of the Yangtze finless porpoise (Neophocaena phocaenoides asiaeorientalis), an endangered freshwater population endemic to China, the complete mtDNA control region was examined in 39 individuals belonging to seven different stocks inhabiting the middle and lower reaches of the Yangtze River. Very low genetic diversity was found (nucleotide diversity 0.0011 +/- 0.0002 and haplotypic diversity 0.65 +/- 0.05). The mtDNA genetic pattern of the Yangtze population appears to indicate a founder event in its evolutionary history and to support the marine origin for this population. Analyses by F-st and Phi(st) yielded statistically significant population genetic structure (F-st = 0.44, P < 0.05; phi(st) = 0.36, P < 0.05). These results may have significant implications for the management and conservation of the Yangtze finless porpoise in the future.

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Fazey, I., Fischer, J., Lindenmayer, D. B. (2005). What do conservation biologists publish? Biological Conservation, 124 (1) 63-73. RAE2008