Turbidity control and fisheries enhancement in a bottomland hardwood backwater system in Louisiana (USA)

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Selected abstracts

Most of these agricultural drainage waters contain high concentrations of salts and naturally occurring trace elements. Substantial numbers of waterbirds are exposed to contamination by selenium in the evaoporation ponds. Four methods are recommended for implementation: remove levee vegetation, remove windbreaks, deepen the ponds, and haze birds. A number of other methods are recommended for further consideration because they ar to have good prospects for reducing the contaminaon hazard: steepen interior levee slopes, apply herbicides and insecticides,place netting on pond shorelines, and provide freshwater habitat adjacent to evaporation ponds. It may be necessary to use a combination of methods. -from Authors

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92Z/00043 Turbidity control and fisheries enhancement in a bottomland hardwood backwater system in Louisiana (USA) M. S. Ewing, Regulated Rivers Research & Management, 6(2), 1991, pp 87-99. ChronicaUy high turbidity (>100 FTU) was the major factor limiting game fish production. High turbidity can be related to man-made alterations of natural flood patterns that had changed the major source of backwater flooding from Black River to the highly turbid Red River. In September, 1986, a construction project was undertaken to restore flood patterns to approximate natural conditions. A significant decrease in turbidity and an increase in game fish production have been noted. -from Author 92Z/00044 The National Rivers Authority: a conservation agenda D. Harper, ECOS: a Review of Conservation, 12(3), 1991, pp 13-20. Examines some of the issues in four water-based environmenta. In the area of lake water quality, eutrophication rather than acidification is the problem in England. In the area of river water quality, samples are taken too infrequently over too few sites, but even this inferior system has found a major decline in s!~e.cies richness and evidence of serious pollution incidents. River water quality is related to river management: it seems absurd for some schemes to rush water away in the winter only to have severe water shortages in the summer. The NRA has a golden opportunity to develop multi-purpose schemes in common with agricultural set-aside policies to reclaim whole landscapes, eg floodplains for conservation and recreation. -A.Gilg 92Z/00045 Forty years of Local Nature Reserves J. Box, ECOS: a Review of Conservation, 12(3), 1991, pp 40-43. The first Local Nature Reserve in the UK was set up in 1952 and in 1990 the 200th was declared. The average size is 60 ha in England, 468 ha in Scotland and 192 ha in Wales. Over half fall into the 10-99 ha size category. The author discusses the need for management agreements to be negotiated, and the new opportunities for more designations offered by urban wasteland, waterways and abandoned railway lines. Local Reserves offer a link between local communities and the sustainable concepts of the World Commission on Environment and Development (the Bmndtland Commission). -A.Gilg 92Z/00046 The dunes of England, an example of a national inventory G.P. Radley, tri: Coastal dunes. Proc. 3rd European dune congress, Galway, 1992, ed R.W.G. Carter & others, (Balkema), 1992, pp 439-453. Over a four year period all significant areas of coastal dune in England were located and visited. Remaining areas of semi-natural vegetation on blown sand were surveyed and described using National Vegetation Classification methodology. Information was collected on dune management, land use, and physical processes. The extent and nature of artificial sea defences was also assessed. Examples are given of ways in which the inventory can support the conservation work of English Nature. -from Author

92Z/00047 Mossor som indikerar skyddsvard skog (Bryophytes indicating high nature conservation values in Swedish woodland sites) T. I-Iallingback, SvenskBotanisk Tidskrifl, 85(5), 1991, pp 321-332. The species selected are those which occur mainly in sites where endangered bryophytes occur, are restricted to substrates and inches rarely found in forests of today, and are poor colonizers which are restricted to sites with long woodland continuity. -from English summary 92Z/00048 Management and conservation of sand dunes in Denmark A. Fellberg & F. Jensen, in: Coastal dunes. Proc. 3rd European dune congress, Galway, 1992, ed R.W.G. Carter & others, (Balkema), 1992, pp 429-437. The National Forest and Nature Agency under the Danish Ministry of Environment issues a manual about conservation of nature areas and cultural landscapes. The manual is being rewritten in 1991, the chapter about dunes is discussed here. After a short introduction dealing with the formation of the Danish dunes and their location, the ecological systems and their dynamics are described. The chapter in the manual deals with the white (or the active) dune, green dune, brown dune, grey dune, stone plains, shallow dune lakes, dune moors, Hippophae rhamnoides and Quercus shrubs and internal dunes. Each ecological system is briefly described and the dominant plant species are listed. The need for conservation of the dune areas depends on the imminent threats. In places, the dune system is a vital part of the coastal defence and maintainenee of an even and stable dune has first priority. Intensive human activity (tourism) may be too much for some dune areas and may call for counter-measures. Overgrowth by self-propagating mountain pine and other tree species occurs m places. In some areas lichens are monitored in order to check air pollution. Existing legislation is described; the Danish parliament is currently discussing a new nature protection Bill. The most vulnerable ecological systems ann species are mentioned. -from Authors 92Z/00049 Present a n d future conservation of the Wadden Sea. Proceedings of the 7th international Wadden Sea symposium, Ameland, 1990 N. Dunkers, C. J. Smit & M. SchoU, Netherlands Institute for Sea Research, Publication Series, 20, 1992, 301 pp. After setting out the recommendations of the symposium, the first main section of these proceedings contains keynote papers on the ecological development and the development of the legal and organisauonal structures. This section also contains four contributions describing the future Wadden Sea under different policy scenarios. In the second section the results of scientific research are presented, covering different trophic levels and different forms of human impact. The third section contains management or policy-related contributions. Contributions resent ideas on how management or legal structures can • improved and the aims and goals for the future Wadden Sea. Some of the papers in these sections are abstracted separately in Ecological Abstracts. The next section contams longer scientific contributions, generally on marine and tidal-flat organisms, eight of the nine being abstracted separately. Lastly there are a large number of poster papers, mostly on ecological and marine environmental subjects, and including mapping, effects of dredging, estuarine fauna, land reclamauon, nutrient concentrations and fluxes, eutrophication, coastal bird numbers, geographic information systems and coastal engineering. -J.W.Cooper

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92Z/00050 Grazing domestic livestock in Dutch coastal dunes: experiments, experiences and perspectives H. W. I. Van Dijk, in: Coas~l dunes. Proc. 3rd European dune congress, Galway, ]992, ed R.W.G. Carter & others, (Balkema), 1992, pp 235-250. In the Dutch dunes, a combination of a decreased intensity of livestock grazing and rabbits Oryctolagus cuniculus together with a strongly increased load of nitrogen caused by the pollution of the precipitation and afforestation, has led to a dune vegetation which has become significantly less open in character. Some dune areas, which had an