共查询到20条相似文献，搜索用时 31 毫秒
1.
- 1. The European Water Framework Directive (WFD) requires that Member States differentiate the transitional water bodies into types.
- 2. WFD assigns coastal lagoons to two different water categories, ‘transitional waters’ and ‘coastal waters’ on the basis of freshwater influence.
- 3. The main physical factors that contribute to the genesis and characterization of coastal lagoons are coastal typology, tidal range and climate.
- 4. Italian lagoons are presented as an example of how these physical factors can be used in coastal lagoon characterization and typology. On this basis, a clear distinction of Italian lagoons into two main groups is possible: Northern Adriatic and Mediterranean.
- 5. Large lagoons can be profitably subdivided into a hierarchical system of sub‐basins facilitating both the comparison of parts of the same lagoon and the comparison between different lagoons.
- 6. The basins are consistent water bodies that can be used as managerial units for environmental conservation, species protection and wise use of resources.
2.
3.
- 1. The Water Framework Directive (WFD) requires member states to establish ‘type‐specific biological reference conditions’ for the assessment of surface waters and describes a method for establishing such biological targets. The methodology described in the Directive is based on geographic and physical characteristics and similar to the ‘multimetric’ approach used widely in North America, but contrasts with the biological classification of the ‘multivariate’ approach which is commonly used in Europe.
- 2. An investigation was made of the relative efficiency of the multimetric and multivariate classification approaches in partitioning the observed biological variation of the macroinvertebrate communities of 22 minimally disturbed lakes in Northern Ireland. Furthermore, the accuracy of predictive models based on the two approaches was compared.
- 3. The WFD environmental typologies partitioned the observed biological variation poorly with a maximum ANOSIM R‐value of 0.216 compared with 0.609 for a multivariate biological site classification. The WFD System B approach partitioned more variation than the System A approach.
- 4. The use of a predictive model, based on any of the site classification approaches, resulted in more accurate faunal predictions than a null model. However, the biological model produced the most accurate predictions.
- 5. Canonical correspondence analysis showed that the environmental variables used in the biological classification model explained more variation (28%) than the best‐performing environmental classification model (24%). The most important variable was pH, followed by surface area and altitude. The variables used in all approaches explained more variation when used as continuous rather than categorized parameters.
- 6. The results of this work, the first such comparative study of predictive models in lakes, concur with similar studies in streams. It may be concluded that large‐scale environmental classifications are unreliable as a method for setting type‐specific reference targets for the ecological assessment of fresh waters.
4.
Vanina Pasqualini Christine Pergent‐Martini Catherine Fernandez Lila Ferrat Jean E. Tomaszewski Grard Pergent 《水产资源保护:海洋与淡水生态系统》2006,16(1):43-60
- 1. A monitoring system was developed in two Corsican coastal lagoons (Biguglia and Urbino; Corsica, Western Mediterranean).
- 2. Three species of seagrass (Nanozostera noltii, Ruppia cirrhosa and Cymodocea nodosa) were monitored by (i) measuring spatio‐temporal changes in the seagrasses, using fixed structures, (ii) investigating temporal changes in the biological parameters of the seagrasses, and (iii) mapping their distribution by processing aerial images of both lagoons.
- 3. These investigations showed that, while the two lagoons exhibit, a priori, a certain structural homogeneity (ecosystems based on aquatic plants), they function in different ways that are specifically linked to environmental conditions.
- 4. At present, the estimated net production varies from 86 to 469 g C m?2 yr?1 at Biguglia and 190 to 1301 g C m?2 yr?1 at Urbino. These values confirm the richness of these two lagoons, and the interest of using seagrass, by means of regular monitoring, for the conservation and management of coastal lagoons.
5.
6.
- The European Water Framework Directive 2000/60/EC (WFD) defines the ecological status of aquatic systems as the deviation between their present biological state and that which would be expected in the absence of any major human disturbance, referred to by the WFD as the ‘reference condition’ (RC). It assumes that their biotic composition should remain balanced and constant over time. This study tested both assumptions against an analysis of the historical distribution of the fish fauna in a large and highly disturbed Mediterranean basin. If fish communities change substantially over time, it will mean that the validity of the RC concept comes into question.
- Using presence/absence data for historical native fish fauna from the Guadalquivir Basin, distribution changes among sub-basins were quantified by mapping between the nineteenth century and today.
- The range of two native species (Anguilla anguilla and Salmo trutta) has changed significantly. In addition, the diadromous species assemblage has almost become locally extinct, with the exception of the eel. Finally, most Guadalquivir sub-basins (94.7%) have suffered major changes in the composition of their fish communities, either by losing native species or by adding new non-native species.
- These results render the definition of any RC unlikely. In Mediterranean areas, the WFD objective of ‘good ecological status’ recovery based on the integrity of aquatic communities is a theoretical rather than a real goal. Nonetheless, the WFD provides an ecological guiding principle that can also be transferred to the conservation of freshwater ecosystems.
- As an alternative to the RC concept in Mediterranean lotic ecosystems, specific multimetric indices can be used, based on expert criteria, the metrics of which can also relate to the conservation value of water bodies, and not only to their ecological status.
7.
Biodiversity values of remnant freshwater floodplain lagoons in agricultural catchments: evidence for fish of the Wet Tropics bioregion,northern Australia 总被引：1，自引：0，他引：1 
下载免费PDF全文
下载免费PDF全文 Angela H. Arthington Paul C. Godfrey Richard G. Pearson Fazlul Karim Jim Wallace 《水产资源保护:海洋与淡水生态系统》2015,25(3):336-352
- 相似文献
8.
9.
Desktop classification of inland wetlands for systematic conservation planning in data‐scarce countries: mapping wetland ecosystem types,disturbance indices and threatened species associations at country‐wide scale 下载免费PDF全文
下载免费PDF全文 Heidi van Deventer Jeanne Nel Namhla Mbona Nancy Job Justine Ewart‐Smith Kate Snaddon Ashton Maherry 《水产资源保护:海洋与淡水生态系统》2016,26(1):57-75
10.
11.
J.S. Rowan J. Carwardine R.W. Duck O.M. Bragg A.R. Black M.E.J. Cutler I. Soutar P.J. Boon 《水产资源保护:海洋与淡水生态系统》2006,16(6):637-657
- 1. In the absence of a standard procedure for characterizing the physical habitat of lakes in Europe, this paper describes the development of a multi‐purpose Lake Habitat Survey (LHS). The technique has been designed to meet the hydromorphological assessment needs of the Water Framework Directive (WFD), as well as to assist in monitoring the condition of designated sites in the UK and for wider application in environmental impact assessments and restoration programmes.
- 2. LHS involves detailed recording of shoreline features at a number of plots (Hab‐Plots), complemented by a meso‐scale survey of the entire lake, including shoreline characteristics and pressures, and modifications to the hydrological regime. A temperature and dissolved oxygen profile is also compiled at the deepest point of the lake (Index Site). Existing databases are exploited where possible, and remote sensing data (e.g. aerial photographs) are used to assist field‐based observations.
- 3. Initial field trials demonstrated that the consistency of the method, whether conducted by boat or on foot, was high. More than 250 surveys were carried out across the UK in 2004 through collaboration with the statutory environment and conservation agencies.
- 4. Two levels of complexity were tested — a full version requiring 10 Hab‐Plots and an abridged version, LHScore, involving four plots and omitting the Index Site. While 8–10 plots were required to capture the full diversity of features at complex sites, LHScore data were sufficient to generate metrics for classification purposes.
- 5. A Lake Habitat Modification Score (LHMS) may be calculated from LHS data. This synthesizes a wide array of hydromorphological and human pressures and has direct applications for assessment of ecological status under the WFD. Preliminary analysis illustrates a spectrum of hydromorphological alteration of 82 lakes in the UK.
- 6. Further considerations are discussed, including the prospect that the LHS protocol might form the basis of a European standard developed through CEN (Comité Européen de Normalisation).
12.
13.
14.
15.
16.
17.
18.
- 1. The objectives of the present study were to describe and analyse the composition and structure of aquatic Coleoptera and Hemiptera assemblages in three coastal lagoons of north‐western Spain during a one year cycle, in order to evaluate their relative adequacy to provide information about the conservation value of lagoonal habitats and sites. The lagoons are designated as Special Areas of Conservation (SAC) under the European Union Habitats Directive and two of them are also protected by the Ramsar Agreement. Several abiotic variables, including salinity, were recorded at the time of sampling.
- 2. In total, 67 species (52 Coleoptera and 15 Hemiptera) and 6568 adult individuals (2664 Coleoptera and 3904 Hemiptera) were collected. In all pair‐wise comparisons Kendall's coefficients of concordance between lagoons were higher for Hemiptera than for Coleoptera, indicating that Hemiptera assemblages were more similar across sites.
- 3. Most species recorded had a wide Palearctic distribution and only three species of water beetles could be considered endemic to Iberia: Hydroporus vagepictus, Hydroporus vespertinus and Hydrochus angusi. Similarly, the species collected had a widespread distribution in the Iberian Peninsula as the only species considered to be rare taxa at this scale were Hydrochus angusi and Cymbiodyta marginella among the Coleoptera and Sigara scotti and Notonecta glauca glauca among the Hemiptera.
- 4. The results do not support the idea of distinct aquatic insect assemblages for coastal lagoons in the Iberian Peninsula. Comparisons of the numbers of interior (non‐coastal) and coastal provinces of the Iberian Peninsula where the species had been recorded showed they had been recorded in a larger proportion of interior provinces.
- 5. Salinity seemed to reduce species richness in both groups while the results of a canonical correspondence analysis (CCA) showed that the majority of species responded negatively to salinity.
- 6. This study suggests that species richness and rarity of aquatic insect assemblages may underestimate the conservation value of lagoonal habitats because their net contribution to catchment biodiversity is likely to be low.
19.
20.
- 1. Mesotrophic lakes are a threatened habitat in the United Kingdom (UK), and are specified within the UK Biodiversity Action Plan (UKBAP) as requiring protection. Lough Melvin is a large mesotrophic lake that is of particular interest owing to the genetic diversity of its brown trout, but it is currently showing signs of nutrient enrichment.
- 2. In 1990, average lake total phosphorus (TP) was less than 19 µg P L?1 but increased to 29.5 µg P L?1 by July 2001. Inflow TP also increased from 34 µg P L?1 to 41 µg P L?1 over the same period. Neither phosphorus nor nitrogen appeared to be limiting.
- 3. Despite higher lake TP, annual chlorophyll a did not increase, remaining less than 5 µg L?1. The phytoplankton was dominated by cyanobacteria and seems to have remained unchanged since the 1950s. Rotifer numbers increased significantly after 2001 but the macro‐zooplankton did not. The absence of a phytoplankton response to P enrichment is attributed to light limitation caused by peat staining and thorough mixing.
- 4. In the catchment, an accelerated programme of clear‐felling began in 1999. Recent changes in the lake are consistent with the known impacts of clear‐felling conifers on peat soils, namely larger P and dissolved organic carbon (DOC) losses. The latter was reflected in a lower Secchi depth and an enhanced microbial food‐web supporting a larger rotifer population.
- 5. It is suggested that, for the purposes of the Water Framework Directive (WFD), Lough Melvin and other large, alkaline but peat‐stained lakes may be treated as a distinct lake type as they do not fit easily into the conventional classifications of dystrophic or mesotrophic lakes.