243 resultados para freshwater macrophytes
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This article provides insights into a particular aspect of freshwater research in China and its wider implications for western researchers. The senior author has collaborated with Professor Zhang Zhaohui from Guizhou Normal University to investigate the travertines of China. Travertines are freshwater carbonate deposits accumulating in hard-water springs and rivers. In some areas they develop rapidly, forming picturesque ascades and magnificent travertine-dammed lakes. Some of China's most famous tourist sites are the result of travertine formation. The travertine-depositing environment is a unique fast-flowing ecosystem inhabited by specialist plants and animals. The authors examine the freshwater algae of the Doupe Pool travertine situated on the Beishuihei River in Guizhou Province and compare their distribution on travertines elsewhere in the world.
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The importance of ponds for biodiversity in Britain has been demonstrated by a number of studies. However, most of the research and interest has been directed at permanent waterbodies, and temporary ponds have been largely neglected. In this article the author present some preliminary findings from a project which aims to fill some of the many gaps in our knowledge of temporary ponds in Britain. The project, which runs for three years until the end of 2001, aims specifically to investigate the ecology of temporary ponds in England and Wales by describing (i) their wetland plant and macroinvertebrate communities, (ii) their physico-chemical characteristics, and (iii) their value as a biodiversity resource. The article focuses on the assessment of temporary ponds as a biodiversity resource and briefly considers aspects of species richness, rarity and distinctiveness. Where possible, temporary ponds are compared with other waterbody types, mainly permanent ponds from the National Pond Survey (NPS), to give the results a broader context.
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Although the toxicity of cyanobacteria has been known for many years, cyanobacteria-related problems in the UK were generally limited in frequency. However, this all changed and became of national concern following the exceptional environmental conditions in the autumn of 1989, when widespread cyanobacterial blooms and scums developed in fresh waters. This paper summarises the Environment Agency's monitoring programme for freshwater algae since 1991 and describes the actions the Environment Agency has taken as a result of the monitoring data.
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This article explores the diversity of scientific disciplines and paradigms, their relevance for policy development, how policy emerges throughout society,-and the mechanisms by which scientists can promote the value of science in policy formation. The author gives examples from various countries where freshwater science was used to inform policy.
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This brief article provides some of the background to the publication of The Freshwater Algal Flora of the British Isles (John et al. 2002). This publication updates West and Fritsch's A Treatise on British Freshwater Algae (2nd edition) which was published in 1927. Taxonomic experts on the major freshwater algal groups were approached and almost all agreed to collaborate. The book which has taken more than 10 years to complete is illustrated with over 2000 line drawings and there are 20 half tone plates.
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Freshwater crabs are a strangely neglected component of the world's inland aquatic ecosystems. Despite their wide distribution throughout the tropical and warm temperate zones of the world, and their great diversity, their role in the ecology of freshwaters is very poorly understood. This is nowhere more true than in Africa, where crabs occur in almost every freshwater system, yet even fundamentals such as their higher taxonomy are yet to be determined. This review will attempt to stimulate interest in this fascinating group of organisms by summarising what little we do know about freshwater crabs in Africa. The author describes habitat, reproduction, diet, population density, terrestrial activity and economical importance of African freshwater crabs. The article concludes with an assessment of threats and conservation. In an appendix the author describes the five families of freshwater crabs which are recognised in Africa.
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The year 2004 marked the 75th anniversary of the Freshwater Biological Association. The author reflects the history of the Association focusing on the main events of the last 25 years since 1979.
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This article outlines the development of freshwater science between 1900 and 2000 and in particular traces British contributions, both to a deepened knowledge of specifics and to their interrelation as environmental and ecological science. The author provides a selected bibliography of important publications relevant to the topic of the article.
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This study was conducted to identify a functioning fingerlings production and delivery system for a sustainable aquaculture development. Data were collected from 234 respondents randomly sampled from a population of 600 fish farmers. Results indicated that farmer-to-farmer was the major source of fingerlings production and distribution system. Although this source accessed disadvantaged groups like the rural based, resource poor, less educated and women, it lacked knowledge on how to produce good quality fingerlings. These results suggest that a decentralized and privatized fingerlings production and delivery system should be promoted. For this system to operate effectively the aquaculture department should first identify potential zones for aquaculture growth and profit motivated fingerlings producers and distributors. Furthermore, the institutional mechanism through which farmer-to-farmer will operate should be identified and strengthened through short and long term training programmes. The government should support the system by providing guidelines for good quality fingerlings management; maintain brood stock parents and technical training in Bangladesh.
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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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Lough Erne in Northern Ireland has been the subject of much research over the last 30 years by, amongst others, the Department of Agriculture and Rural Development (DARD). In this article, the authors provide a summary of a workshop held on the 16–17th October 2003 in Enniskillen, on the shores of Lough Erne, which gave an opportunity to step back and take a holistic look at the Erne lakes. Ecological change has been driven by many factors, including land use changes and species invasions. The workshop consisted of five sessions which are summarised in this article: Session 1 – Invasive species, nutrients, phytoplankton and macrophytes; Session 2 – Zooplankton, benthic macroinvertebrates and fish; Session 3 – An ecosystem approach – relating the previous sessions; Session 4 – How does Lough Erne fit into lake classifications? Implications of the Water Framework Directive; Session 5 – Using new techniques to examine food webs and species invasions. Identifying a future research programme for Lough Erne.
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Bassenthwaite Lake is, in many ways, different from the other major lakes in the English Lake District: it is the most northerly, the shallowest, has the largest catchment and the shortest mean retention time. There is also considerable temporal variation in lake level. This article summarises the limnological features of Bassenthwaite Lake, the catchment and physical characteristics before describing the water chemistry, phytoplankton, macrophytes, zooplankton, invertebrates, fish, mammal and invertebrate population. The authors then describe the ecological pressures faced by Bassenthwaite Lake such as nutrients, sediments and introduced species.
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Ephemera danica Müller, 1764 (Ephemeroptera) is one of the largest mayflies found in the British Isles with some females reaching over 30 mm. It is a common and widespread species found in rivers, lakes and streams throughout Europe and is particularly abundant in many of the lowland rivers of the British Isles. The larvae are burrowers – mainly found where silt accumulates below macrophytes. This article gives a general overview of research work on the factors affecting the life cycle of Ephemera danica over a seven year period (1995–2002) on two rivers, the River Test at Leckford in Hampshire and the North Wey at Tilford in Surrey.
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This article introduces a new listing of published scientific contributions from the Freshwater Biological Association (FBA) and its later Research Council associates – the Institute of Freshwater Ecology (1989–2000) and the Centre for Ecology and Hydrology (2000+). The period 1929–2006 is covered. The authors offer also information on specific features of the listing; also an outline of influences that underlay the research, and its scientific scope.
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The present work appertains to a series of investigations in the field of trophodynamics of water bodies conducted by the department of hydrobiology ”Mosrybvtuza” under the leadership of Prof. Director N.S. Gaevska. Usually with quantitative collections of benthos ostracoda are hardly taken account of. But with the employment of special methods it is possible to be convinced that they are encountered in massive numbers. The role of ostracods in the nutrition of fish is recognised as important by many authors. On the question of the feeding of ostracods, in the literature there are only the fragmentary indications about the occurrence in the gut of ostracods of algae (diatoms, desmids) and detritus. The study of the feeding of ostracods was conducted both by the method of dissecting the guts of ostracods taken from natural waters, and by the method of feeding ostracods under laboratory conditions with a variety of food objects. Moreover, with a view to revision of obtained quantitative data, for determination of food requirements of ostracods the respiration method was applied.