摘要:

Abstract1.In Europe, bait supply to anglers from the natural environment involves: (i) bait collection by anglers for own use, (ii) local semi‐professional bait digging and (iii) professional bait digging contracted to distributors.2.The management of bait digging activity is particularly acute where there is a conflict with conservation interests.3.Two case studies are presented describing the population dynamics of: IArenicola marinain the Lindisfarne nature reserve, and IINereis virensin the Menai Strait; both in conservation areas.4.Case I. Populations ofA marinaare subject to marked annual cycles in number and fresh weight. This case illustrates the response of the population to substantial overexploitation leading to a population crash. With the introduction of restrictive legislation the population was re‐established by recruitment of adults from neighbouring unexploited populations.5.Case II illustrates the dynamics of aN. virenspopulation dominated by large old individuals; it does not represent a sustainable resource in contrast with populations of the same species in other locations.6.The management of the exploitation of bait populations in conservation areas is discussed in relation to world patterns of utilization and sup

ISSN:1052-7613    

DOI:10.1002/aqc.3270030102

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

Abstract1.It is hypothesized that the recent intensification of agricultural practice in the coastal fringe of West Connemara, Ireland, has affected the vegetation of vulnerable ecosystems like lakes and wetlands.2.Lakes and wetlands, arranged in three transects running inland from the coast, were studied to detect an assumed decrease in the effects of eutrophication as a result of a decrease in the intensity in land use.3.The data obtained from the vegetation survey in 1988 were compared with those collected at the same sites in 1975. The data were subjected to various multivariate statistics to detect changes in species composition and relationships between these changes and environmental variables such as pH and orthophosphate concentration in the surface waters.4.Changes in species composition are accompanied by changes in environmental factors; notably a marked increase in orthophosphate level indicating an anthropogenic origin for most of the observed changes in vegetation.5.Changes in species composition have also been used to construct a transition matrix for sites between 1975 and 1988. This has served as a basis for a prognosis on the state of the vegetation at these sitescirca2000. Data have also been grouped to indicate lake‐specific patterns in the changes.6.The dynamics of all plant species have been established based on their frequency of disappearance from sites since 1975 and their rate of establishment in new sites in 1988. Special attention has been given to species from the red data list. It is concluded that over the past 13 years species diversity decreased in the whole area, and especially in coastal lakes. Red data list species appeared to be the more vulnerable one

ISSN:1052-7613    

DOI:10.1002/aqc.3270030103

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

Abstract1.A survey is presented of PCB and organochlorine pesticide concentrations in otter (Lutra lutra) spraints (faeces) from 18 catchments/sub‐catchments in Wales and adjacent English counties.2.There were wide differences in concentrations of lindane, dieldrin, DDE and PCBs between catchments and at sites within catchments. Only PCBs were considered likely to be of significance in influencing otter populations. Mean PCB concentrations (but not those of dieldrin and DDE) were inversely related to otter population performance (as measured by both catchment distribution and sprainting intensity) between catchments.3.It is suggested that PCB contamination is exerting a negative impact on otter populations in four catchments, while there is concern over four others. A study of food chain contamination should be an essential component of otter conservation strategies at both the national and local leve

ISSN:1052-7613    

DOI:10.1002/aqc.3270030104

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

Abstract1.This paper describes New Zealand's Resource Management Act in relation to freshwater management and conservation.2.The development of the Act is described with reference to the consolidation and integration of earlier legislation. The central concept of sustainable management is more limited than the related concept of sustainable development, and places constraints on activities which have environmental impacts.3.The specific provisions relating to fresh water are noted, and the resource consents required for taking water, damming or diverting watercourses, and discharging into water, or onto land where the discharge may reach water, are described. The relation of riparian management to the requirement for protection of fish habitat is noted, and water conservation orders are described. Attention is given to the likely implications for managers.4.An attempt is made to anticipate difficulties that may arise in implementing the Act; in particular, the possible balancing between socio‐economic and ecological considerations. The specific features of the freshwater environment are considered from the viewpoint of management, and the problems involved in tradeability are noted. Attention is drawn to the scope of the Act in the attempted integration of most, but not all, environmental considerations, and a final evaluation suggests that economic growth is likely to present a substantial challenge to the purpose of the Ac

ISSN:1052-7613    

DOI:10.1002/aqc.3270030105

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

ISSN:1052-7613    

DOI:10.1002/aqc.3270030106

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

ISSN:1052-7613    

DOI:10.1002/aqc.3270030107

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

ISSN:1052-7613    

DOI:10.1002/aqc.3270030108

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

ISSN:1052-7613    

DOI:10.1002/aqc.3270030101

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY