摘要:

Abstract1. The possible impacts of abstraction of water from streams and rivers in the UK have generated concern in conservation bodies.2. This paper examines the feasibility of using biotic scores and predictions from the computer‐based RIVPACS system to assess the effects of abstractions on benthic fauna.3. Control and ‘impacted’ sites on 22 rivers which experienced abstractions for hydroelectric power generation, supply of drinking water (either directly or through groundwater abstraction), spray irrigation and fish farming, were examined.4. The ratios of observed to predicted biotic scores and comparison of observed fauna with that predicted by RIVPACS were used to assess the biological quality of the sites.5. Only 11 of the 51 sites on the 22 rivers showed signs of reduced environmental quality. These included eight sites on a small lowland stream which receives run‐off from fertilized agricultural land and is subject to spray irrigation; two sites on upland streams which had experienced severe spates prior to our survey and a small chalk stream, the Pang.6. Discharge, baseflow, substrate and altitude were factors which explained most of the variation in faunal parameters such as biotic score, numbers of species, numbers of families and total abundance.7. The main conclusions of the study are that upland streams did not appear to suffer adverse effects as a result of abstraction whereas lowland streams appeared to be more degraded, but with the exception of the Pang this could not necessarily be attributed to abstraction.8. Biotic scores with RIVPACS cannot be used to set ‘minimum ecological flows’ but can be used either directly, to assess site‐quality and to identify areas of concern which may or may not be related to abstraction; or indirectly, by reference to the RIVPACS data‐base to assess the conservation interest of invertebr

ISSN:1052-7613    

DOI:10.1002/aqc.3270020102

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract1. To consider fully the conservation management of freshwater fish, it was important to know which fish were already in the protected environment of National Nature Reserves (NNRs) — the principal sites for nature conservation in Great Britain. For this reason, 235 NNRs declared by the Nature Conservancy Council (NCC) were surveyed for freshwater fish between 1987 and 1990 by questionnaires to the wardens, by compiling data from other sources, and, where necessary, by field sampling. The presence of fresh waters (as lakes, ponds, rivers and streams) was also recorded. The survey was organized to follow the country and regional structure by which nature conservation was administered by the NCC so that the results could be considered accordingly.2. Seventy five percent of NNRs contain fresh waters and, of these, just over 20% have no fish. Of the 51 fish species available 37 (73%) were recorded in NNRs. NCC regions with most fish species are: SW Scotland, West Midlands and East Anglia, but NW Scotland has the highest total of species occurrences in NNRs. In terms of both the numbers of species and their frequency of occurrence, NW and NE England are notably the lowest. The most common fish in NNRs are Eels, Brown Trout and Three‐spined Sticklebacks.3. The results for species and for sites (NNRs) are discussed from the viewpoint of fish conservation. The majority of fish in NNRs are those most common in Great Britain. Two of the species recorded (Powan and Smelt) are currently important for conservation, but several of those most threatened do not occur in NNRs. A number of NNRs have diverse fish communities, but only six have significant fish conservation value, of which Loch Lomond NNR is outstanding.4. There is considerable scope through NNR management to improve fish conservation and it is suggested that the acquisition of new reserves for threatened species should be conside

ISSN:1052-7613    

DOI:10.1002/aqc.3270020103

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract1. Seventy‐two per cent of the Flathead River catchment (22 241 km2) is federally designated and protected as wilderness or national park. Thus, the catchment remains one of the more pristine areas of its size in the temperate latitudes of the world.2. Discharge in the downstream reaches of the river system outside the protected areas is regulated by three dams for flood control and hydropower production. These dams have blocked natural migration of native fish from Flathead Lake (496 km2) and isolated populations in sub‐catchments. Temperature and erratic flow fluctuations have altered phenologies of river zoobenthos and fish, and in dam tailwaters aquatic biodiversity is drastically reduced in comparison to unregulated segments.3. Ecological problems caused by changing water quality conditions, altered land‐use patterns and introductions of non‐native biota are interactive with the impacts of stream and lake level regulation, thereby emphasizing the complexity of this river–lake ecosystem.4. Mitigation of the effects of regulation is compromised by differing management priorities and regulatory mandates of County, State, Tribal, and Federal agencies responsible for natural resource management within the catchment. Moreover, economic and ecological interests outside the Flathead influence the way flows are regulated within the catchment.5. The most pervasive influences of stream and lake regulation can be ameliorated by retrofitting the hypolimnial release dam with a selective depth outlet structure to allow temperature control, and by controlling changes in flow rates to create a more natural hydrograph in the tailwaters of the large dams. Allowing fish passage by construction of fish ladders is problematic because upstream passage will commingle native species that were isolated upstream by construction of the dams with non‐native species that were introduced subsequently below the dams. Cascading food web interactions elicited by invasions of non‐native biota may offset any advantage to native stocks gained by passage and/or augmentation with hatchery stocks.6. Mitigation must be adaptive in the sense that unanticipated effects and interactions with other management objectives can be documented and alternative action can be implemented.7. This case history of the effects of stream and lake level regulation, and the approaches to management reviewed in this paper, should serve as a lesson in river

ISSN:1052-7613    

DOI:10.1002/aqc.3270020104

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract1. Recent data on habitat characteristics and the animal and plant communities from 166 brackish lagoons in Great Britain have been analysed to interpret their community stucture and the environmental features important to maintaining the diversity of specialist lagoonal species.2. Lagoons supporting a diverse community of specialist species of restricted distribution are considered to be the most valuable in conservation terms.3. Lagoons are concentrated in the south and east of the country, are predominantly shallow with fine sand and mud sediments and cover a range of sea‐inlet types, areas and salinities (from zero to hyperhaline).4. The environmental characteristics of lagoons show more variability than those of ambient sea‐or estuarine water.5. Six suites of species are identified: freshwater species, stenohaline marine lagoonal specialists, euryhaline lagoonal specialists, estuarine species tolerant of lagoons, estuarine species incidental in lagoons and underrecorded species.6. The lagoons are categorized as freshwater sites and groups of saline sites of a range of conservation value in terms of their community, from high value sites dominated by stenohaline specialist species to sites supporting no specialist lagoonal community.7. The higher value sites are bar‐built or sluiced lagoons with a channel inlet, with salinities close to 35%0, a heterogeneous sediment, predominantly shallow and with larger area if narrow. Spatial density of lagoons may be important in recruitment of stenohaline specialist species, and frequent exchange of a proportion of the lagoon water with adjacent estuary or sea‐water may be important in maintaining requisite salinity.8. Aspects worthy of further study are ide

ISSN:1052-7613    

DOI:10.1002/aqc.3270020105

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract1. Small scale sand removal (loads of 0.5 to 10 tonnes) is a persistent environmental problem on beaches within Areas of Outstanding Natural Beauty in Northern Ireland.2. This study provides the first objective assessment of the problem in the British Isles, examining both the physical and biological impacts on the beach and the cultural background. These approaches are combined to indicate possible management strategies.3. About 5000 to 6000 tonnes of sediment (sand and gravel) was ‘drawn’ from the eleven beaches in the study area during 1990. The rate and magnitude of sediment removal varied between and within sites, by day of the week and by season.4. There are two direct impacts to the shoreline environment. First, over a long period, the amount of sediment removed is enough to cause serious erosion on some smaller beaches. Up to 80% of shoreline recession can be explained by sand lost through extraction. Second, extraction appears to lead to an impoverished beach fauna. More indirect impacts include the loss of aesthetic quality (important in an area reliant on tourism), disturbance of wildlife, damage to and possible reduction of access provision, and impairing the ability of the shoreline to develop foredunes.5. The views of the coastal community are quite polarized. One group (about 55%) wish to see sand removal cease, while the remainder (45%) do not. Interviews with people actually taking sand suggest that they do not see their actions as damaging the environment.6. Several options for future management are discussed. It would appear that a management prescription for each site, backed by legislation, might relieve the prob

ISSN:1052-7613    

DOI:10.1002/aqc.3270020106

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract1. This paper discusses the characteristics of scientific information used in river conservation and management.2. Information should be appropriately focussed, achieving a balance between the ideal and the achievable, recognizing the functioning of riverbasinsand not merely riverchannels.3. Technical data need to be presented in a way that is readily understood by decision‐makers — simply, but not simplistically. This is discussed using examples such as river corridor mapping and the application of numerical indices of water quality and conservation value.4. Ideally, river management policy and practice requires a scientific input that is both unequivocal and authoritative. Frequently, however, disagreement over its interpretation delays information transfer.5. The results of applied studies in freshwater science are not always as accessible as they should be to river managers. Once acquired there must be a genuine willingness by planners to incorporate the results of ecological research into project design, a process often hindered by complex bureaucratic structures. It is thus argued that operational flexibility in river management schemes is desirable, and post‐project appraisal esse

ISSN:1052-7613    

DOI:10.1002/aqc.3270020107

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

ISSN:1052-7613    

DOI:10.1002/aqc.3270020101

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY