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1.
Although benthic macrophytes must be considered in monitoring programs to establish the ecological status of transitional and coastal waters in the European Union, the patterns of variability in species composition of macrophyte assemblages in Mediterranean coastal lagoons has scarcely been studied. In this work the spatial (both vertical and horizontal) and seasonal dynamics of macrophyte assemblages in a coastal lagoon (Mar Menor) are compared with those of open coastal assemblages in the SW Mediterranean to analyze any biological variability in lagoon assemblages and the factors that determine such variability. Different assemblages, characterized by well defined groups of species, can be described according to their isolation from the open sea and the type of substratum; at the same time, a vertical zonation pattern, similar to that found in all marine communities but more compressed, exists. This implies that when applying the EU Water Framework Directive or assessing environmental impact, a lagoon should not be considered spatially uniform and unique unit but as a mosaic of assemblages.  相似文献   

2.
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3.
The Bolmon lagoon (South of France) is an oligo-mesohaline coastal lagoon that has undergone intense eutrophication in the past decades, resulting from a strong concentration of human activities in its drainage basin. Consequently, it exhibits some characteristics typical of an advanced trophic state; namely, the disappearance of submerged vegetation, the permanently intense phytoplankton growth and the recurrence of cyanoprokaryote blooms. As cyanoprokaryote dominance in south-temperate saline lagoons is little reported, we carried out this study in order to understand the seasonal variations in the phytoplankton composition and biomass, and to analyse the influence of environmental parameters such as salinity, nutrients and climate on the seasonal succession of species. In this lagoon, the phytoplankton was permanently dominated by cyanoprokaryotes, probably because of high availability of nutrients, low light penetration in the water column and frequent turbulent mixing induced by wind. The two most abundant species Planktothrix agardhii (in winter–spring) and Pseudanabaena limnetica (in summer) have low light requirements and are well adapted to a high mixing frequency, which defines the S1 functional group in Reynolds' typology for phytoplankton. Although widely studied in north-temperate lakes, blooms of these typically freshwater species are almost unreported in the Mediterranean area, especially in brackish ecosystems that are not their normal habitat. In the Bolmon lagoon, all their requirements for nutrients, light and mixing are satisfied and they seem to cope with a moderate presence of salt but P. agardhii was less competitive than P. limnetica at highest salinities, the latter being probably more halophytic. Contrary to the observations in lakes located at higher latitudes, the Mediterranean climate seems to induce a typical seasonal pattern of succession characterised by the dominance of P. agardhii (winter) – Chroococcales (spring) – Pseudanabaenaceae (summer) – P. agardhii (autumn, winter). The warm temperatures seemed to have a major influence on the phytoplankton succession, being responsible for the survival of Planktothrix during winter and its rapid and intense development in early spring. Intense mixing and high irradiance in summer promoted the development of Pseudanabaenaceae, as reported in another south-temperate lagoon, the Albufera of Valencia (Spain). The ecological success of Oscillatoriales observed in the Bolmon lagoon is a perfect example of a shift to the “turbid stable state” as proposed for freshwater shallow lakes only. Our work demonstrated that hypereutrophic Mediterranean lagoons can function very similarly to shallow lakes at higher latitudes; but the warmer climate and higher irradiances are probably responsible for differences in the seasonal pattern of species dominance.  相似文献   

4.
《Marine Policy》2007,31(5):599-606
The Solent region in southern England represents one of the highest concentrations of coastal lagoons and saline ponds in the UK. Four lagoon complexes within the region comprise a Special Area of Conservation (SAC), under the European Habitats Directive. The ephemeral nature of coastal lagoons presents a particular management challenge in terms of retaining designated sites in “favourable conservation status”. Consequently, in addition to sensitive management of existing sites, it is important to identify sites for habitat re-creation. A site-specific investigation of Hook Lake in Hampshire is presented. Previously, on the basis of salinity measurements alone, this site was deemed to have progressed naturally through brackish conditions to a freshwater habitat overgrown by reeds Phragmites sp. A more detailed survey, which considered salinity measurements together with an analysis of substratum heterogeneity and invertebrate fauna diversity, suggests that it is still predominantly a freshwater system with an adjacent brackish/saline ditch. Future management, linked to local biodiversity action plan targets, could proactively support the development of this site as a coastal lagoon in order to secure its integration as part of the international conservation designation. However, this is complicated by the need to then recognise and compensate for loss of freshwater habitat, the need to persuade the local community that any change would not compromise coastal defence integrity and ultimately by medium to long-term coastal defence investment decisions.  相似文献   

5.
The response of the aquatic macroinvertebrate communities to freshwater releases of different magnitude and persistence was investigated in two Mediterranean coastal lagoons (Ca l’Arana and Ricarda). The study was carried out during 14 months (June 2004–July 2005) in which different environmental variables and the macroinvertebrate communities associated with two different habitats, the Phragmites australis belt and the deep area of the lagoons, were sampled monthly. Additionally, potential colonizing sources were identified through the analysis of Chironomidae pupal exuviae. The initial response of the communities to the freshwater releases was similar, being characterized by a peak of opportunistic taxa (mainly Naididae), but the late response was different for each lagoon. In the Ca l’Arana, the magnitude of the freshwater release was higher (salinity dropped below five, which is the limit commonly established for most freshwater species) and its persistence was also higher, allowing the colonization of the lagoon by new insect taxa, which replaced the brackish water species. In the Ricarda, the salinity never dropped beyond five and pre-disturbance conditions were rapidly re-established. This, together with the acclimatizing mechanisms showed by the species Chironomus riparius and Hediste diversicolor, permitted the recovery of the pre-disturbance macroinvertebrate community.  相似文献   

6.
长江口3个不同生态系的浮游植物群落   总被引：7，自引：1，他引：7  
初步研究表明 ,长江口及邻近海域存在 3个不同的生态系 ,与以盐度划分的水团 (长江河口水、长江冲淡水、外海水 )基本一致 ,每个生态系包含 1个浮游植物群落。 1997～ 2 0 0 0年的 7个航次调查中共鉴定出浮游植物 393种 ,其中大部分为硅藻。长江口的浮游植物基本可归为 5个类群 :淡水类群、河口半咸水类群、近岸低盐性类群、外海高盐类群、海洋广布性类群。它们自西向东在 3个生态系中有明显的分布格局 ,并且随着长江径流量的变化而摆动和变化。根据栖息水域的盐度浮游植物可分为 3个群落 :河口群落、冲淡水低盐群落、外海高盐群落。  相似文献   

7.
Estuarine, Coastal and Shelf Science has throughout its history considered a diverse range of habitats including estuaries and fjords, brackish water and lagoons, as well as coastal marine systems. Its articles have reflected recent trends and developments within the estuarine and coastal fields and this includes the changing use of well-accepted terms. The term “transitional waters” first came to prominence in 2000 with the publication of the Water Framework Directive of the European Communities [European Communities, 2000. Directive 2000/60/EC of the European Parliament and of the Council of 23 October 2000 establishing a framework for Community action in the field of water policy. Official Journal of the European Communities 43 (L327), 75 pp.], where “transitional waters” are defined as “bodies of surface water in the vicinity of river mouths which are partially saline in character as a result of their proximity to coastal waters but which are substantially influenced by freshwater flows”. The inclusion of the term transitional waters in our own aims and scope reflects the evolution of language in this subject area, encompassing tidal estuaries and non-tidal brackish water lagoons. This article reflects on some of the difficulties posed by the use of the term and its attempts to be inclusive by incorporating fjords, fjards, river mouths, deltas, rias and lagoons as well as the more classical estuaries. It also discusses the problems of including in the term river mouths discharging either into predominantly brackish areas such as the Baltic Sea, or into freshwater-poor areas bordering the Mediterranean.  相似文献   

8.
Macroinvertebrate communities inhabiting shallow sandy bottoms from Catalonia and Balearic Islands coastal waters (Western Mediterranean) were used to develop the Mediterranean Occidental (MEDOCC) index, a new methodology to assess the ecological status (ES) according to Water Framework Directive (WFD) requirements. The dominance pattern of four ecological groups (EG; sensitive, indifferent, tolerant and opportunistic organisms) was studied along a disturbance gradient. Sensitive taxa were present in disturbed situations and tolerant species were related to opportunistic taxa. The thresholds between ES were scaled according to the shifts in the dominance pattern of the EGs. The distribution of the EGs along the gradient of disturbance may vary depending on the studied communities, thus influencing the boundaries defining the ES. With the development of the MEDOCC index it is shown that analysing the response of the communities to the increasing gradient of disturbance is critical to enable an accurate proposal for boundary setting to be made, and to improve the applicability of the indices. AMBI (AZTI Marine Biotic Index), Bentix (Biotic Index), and MEDOCC indices were applied to the dataset to compare the ES obtained.  相似文献   

9.
Results gathered from a monitoring programme on the Mondego Estuary (Western Coast of Portugal) were compliant with findings drawn from other studies, which pointed out that unstable environments, namely estuarine systems, constitute a great challenge for the use of environmental tools such as ecological indices. The Margalef Index, the Shannon–Wiener Index and AMBI were proposed to evaluate the ecological status of benthic communities in the scope of the European Water Framework Directive (WFD) in Portugal and other European member states. In this system these indices were not equally effective in tracking changes in benthic communities that expressed obvious responses to anthropogenic disturbances (eutrophic situations and severe physical disturbance) and to subsequent impacts' cessation. Natural variability played an important role on the indices' response, with estuarine gradient and habitat heterogeneity affecting the ranges of values obtained, and with extreme climate events slowing down the ongoing recovery process. Nonetheless, both natural and anthropogenic variability during the study period could be satisfactorily detected if we accounted for the information provided by all three indices. Based on the whole range of variation observed (a) as a response to different kinds of impacts, and (b) along recovery gradients, as well as accounting for the natural driving forces acting upon estuarine benthic invertebrate communities, we propose a set of reference values for these three indices. This proposal aims at contributing to the implementation of classification tools within the scope of the European WFD.  相似文献   

10.
The European Water Framework Directive (WFD, 2000/60/EC) recommends the development of biotic indices for assessing the ecological quality status of water bodies. The Benthic Index based on Taxonomic Sufficiency (BITS) was specifically developed for lagoonal systems, according to the tolerant/opportunistic approach. Macrobenthic data, variables indicative of eutrophication and variables indicative of sedimentary organic matter quality were collected during 18 surveys carried out between 2004 and 2005 in three Adriatic coastal lagoons (Venice Lagoon, Sacca di Goro, Lesina Lagoon). The relationship between environmental variables and biotic indices (AMBI, BENTIX, BITS, BOPA and FINE) was tested using multivariate analyses. Indices based on species classification level appeared to relate better with the variables describing organic matter quality, whereas BITS, which is based on family classification level, seemed related to eutrophication indicative variables, such as sulphide, ammonium, dissolved oxygen and orthophosphate concentrations. The BITS approach reduces the costs associated with sorting and identification of organisms. Providing a rapid assessment of ecological quality, and producing an ecologically relevant classification, BITS seems a promising tool for monitoring programs of Adriatic lagoonal ecosystems. Its sensitivity in reflecting the field conditions elsewhere, however, remains to be assessed.  相似文献   

11.
The intercalibration exercise is an important step in the building process of the surface water ecological quality assessment, which is required by the Water Framework Directive (WFD). Its aim is to apply the water quality classification in a uniform manner to all the Member States belonging to the same eco‐region. Cyprus, France, Greece, Italy, Slovenia and Spain participated in the soft‐bottom benthic invertebrate subgroup for the Mediterranean coastal region. The methodologies proposed by Member States were applied and tested; the results were compared and harmonized to establish agreed and comparable boundaries for the benthic invertebrate ecological status classes. The national methods used in the intercalibration process were: for Cyprus and Greece, the Bentix Index; for Slovenia, a combination of AZTI Marine Biotic Index (AMBI), richness and diversity with the use of factor and discriminant analysis (Multimetric AMBI); for Spain, a new index, named MEDOCC, which is an adaptation of the AMBI index to the Western Mediterranean area. Italy and France tested different methods, none of which have been officially adopted. Final class boundary values for the different official classification systems were obtained and compared. Besides describing methods and results obtained by the different countries, the Italian situation is examined in more detail. All the above methods have been applied to Italian data, but the results were not conclusive. Major causes for concern are related to insufficient sites and data, to the lack of real non‐impacted reference sites, and to the difficulties in validating the ecological status classification in sites not showing a pollution gradient.  相似文献   

12.
The status of water quality of Irish estuaries is reviewed; this sheds light on the rationale behind the design of the national monitoring programme. Relative to other EU Member States, Ireland's coastal monitoring programme is relatively young and not as advanced. The monitoring programmes in Ireland pre Water Framework Directive (WFD) were structured on a salinity-based typology, with an emphasis on quantifying the variability of the component elements. Although monitoring is a significant obligation under the WFD, there is little guidance on developing monitoring protocols; Member States are developing ad hoc monitoring programme. The Irish Environmental Protection Agency (EPA), responsible authority, undertook research programmes to assist design and implementation of the WFD. A substantial new national monitoring programme was developed. However, the Irish programme is not optimised; the programme is being refined to include elements not yet covered, notably the biota. New research, by the authors, aims to develop a robust approach towards monitoring integrating data and model results. This paper presents changes in Irish marine water quality monitoring policy and some of the associated research necessary to change policy.  相似文献   

13.
Abstract. The temporal variations of nutrients, chlorophyll a (chl a ), suspended particulate matter (SPM) and particulate organic carbon (POC) were measured over 12 months in three shallow coastal brackish water lagoons of the Amvrakikos Gulf, Ionian Sea. Two of the lagoons, Tsoukalio and Rodia, are interconnected but separated from Logarou by a narrow strip of land. Logarou has a better water exchange with the sea as indicated by the higher salinity and dissolved oxygen concentrations and the smaller variation of the above-mentioned parameters. Nitrate concentrations were largely the same in the three lagoons and higher than in the Amvrakikos Gulf. Phosphate concentrations in Logarou exceeded by far those of Tsoukalio/Rodia; the increased phosphate levels recorded in January caused an extended phytoplankton bloom with chl a concentrations higher than in the other two lagoons. Chl a in Tsoukalio was positively correlated with nitrate whereas in the most shallow lagoon, Logarou, it showed a positive correlation with light winds (force 4 and lower), probably caused by resuspension from the sediment. Increased phytoplankton biomass in Logarou coupled with the better water exchange may be related to the higher fish production in this lagoon.  相似文献   

14.
The Huizache–Caimanero coastal lagoon complex on the Pacific coast of Mexico supports an important shrimp fishery and is one of the most productive systems in catch per unit area of this resource. Four other less important fish groups are also exploited. In this study, we integrated the available information of the system into a mass-balance trophic model to describe the ecosystem structure and flows of energy using the E approach. The model includes 26 functional groups consisting of 15 fish groups, seven invertebrate groups, macrophytes, phytoplankton, and a detritus group. The resulting model was consistent as indicated by the output parameters. According to the overall pedigree index (0.75), which measures the quality of the input data on a scale from 0 to 1, it is a high quality model. Results indicate that zooplankton, microcrustaceans, and polychaetes are the principal link between trophic level (TL) one (primary producers and detritus) and consumers of higher TLs. Most production from macrophytes flows to detritus, and phytoplankton production is incorporated into the food web by zooplankton. Half of the flow from TL one to the next level come from detritus, which is an important energy source not only for several groups in the ecosystem but also for fisheries, as shown by mixed trophic impacts. The Huizache–Caimanero complex has the typical structure of tropical coastal lagoons and estuaries. The TL of consumers ranges from 2.0 to 3.6 because most groups are composed of juveniles, which use the lagoons as a nursery or protection area. Most energy flows were found in the lower part of the trophic web.  相似文献   

15.
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16.
The Land-Ocean Interactions in the Coastal Zone (LOICZ) biogeochemical model (LBM) was applied at different temporal and spatial scales in 17 Italian lagoons of the LaguNet network (http://www.dsa.unipr.it/lagunet). A series of alternative assumptions taking into account benthic vegetation and sedimentary fluxes were introduced and compared with the classical LBM approach at various time scales. The reliability of the LBM application to the seventeen Italian lagoons was tested by comparison to a pool of shallow coastal systems from the global LOICZ database with comparable depths and sizes. The nutrient loads of the Italian sites can be considered relatively low, particularly for dissolved inorganic phosphorus (DIP). Although the median values of estimated internal transformations (source-sink) of both dissolved inorganic phosphorous and nitrogen at the LaguNet sites were comparable with the selected LOICZ sites, the positive and negative extreme values were one order of magnitude lower. Overall, the LBM applications to the Italian sites gave good quality budgets for shallow systems subjected to relatively low nutrient inputs and with a wide range of primary producer communities, including seagrass, macroalgae and phytoplankton. Furthermore, stoichiometry of Carbon:Nitrogen:Phosphorous for the different primary producer groups allowed the integration of previous studies by identifying a series of relationships between nutrient loads and ecosystem functions.  相似文献   

17.
Lagoa de Araruama in the state of Rio de Janeiro, Brazil, is a hypersaline coastal lagoon as a result of semi-arid climate conditions, a small drainage basin and a choked entrance channel. The lagoon has been continuously hypersaline for at least 4·5 centuries, but the mean salinity has varied substantially. It has recently decreased from 57 to 52 as indicated by density (salinity) measurements between 1965 and 1990.Analysis of more than 20 years of salinity time series data, in addition to monthly lagoon cruises to measure the spatial salinity distribution, indicate that the lagoon salinity largely fluctuates in response to the difference between evaporation and precipitation. The major factor explaining the long-term trend of decreasing salinity in the lagoon is the constant pumping of 1 m3s−1of freshwater to the communities surrounding the lagoon from an adjacent watershed, and subsequent discharge of this water into Lagoa de Araruama. The net salt budget is primarily a balance between the advective import of salt from the coastal ocean and eddy diffusive export of salt to the ocean, although the extensive mining of salt from the lagoon during past decades is also a small but significant contribution to the salt budget. The flushing half-life is proposed as a useful time scale of water exchange, is calculated based on a combination of hydrological and tidal processes, and is excellent for comparison of lagoons and assessing water quality changes. The flushing half-life measures 83·5 days for Lagoa de Araruama, considerably longer than for most other coastal lagoons. The proposed dredging of a second ocean channel to Lagoa de Araruama is probably not a good idea. It is likely to accelerate the decrease of lagoon salinity and somewhat improve the lagoon water exchange. At the same time, this will eliminate the apparent buffering capacity provided by the hypersaline environment, and thus may potentially cause water quality problems.  相似文献   

18.
The Water Framework Directive (2000/60/EC) requires member states to classify and enhance the ecological quality of water bodies in accordance with their type. To estimate the effect on type of the natural variability of lagoons, we applied a two-dimensional hydrodynamic model to the lagoon of Venice. The model calculated the mean annual spatial distributions of two variables: salinity and residence time. The standard deviation of salinity was also included, in order to estimate the variation of salinity values around the mean, which is associated with the instability of the mean salinity value.A highly detailed numerical grid was calibrated and high-frequency tributary discharge data were used.The simulations, under realistic forcing conditions, are based on the years 2003 and 2005. The former was characterized by low precipitation, around 30% less than the typical value.A comparison of model results and measurements shows the high reliability of the model in reproducing the spatial distribution and temporal evolution of salinity.We found strong inter-annual variation in salinity, standard deviation of salinity and residence time. The effect on the typing process is that the most representative types shift from one category to another.On the basis of the spatial patterns of the variables and their superposition, we identified types that described the bulk of the lagoon.This numerical tool offers support for lagoon management on various levels, in terms of both WFD requirements and other applications, by: (1) providing unbiased and objective zoning indications for the basin; (2) evaluating the response of water quality elements; (3) establishing the reference status of a water body; and (4) establishing a hierarchical division of a lagoon that can be used to select an appropriate number of sampling stations for monitoring.  相似文献   

19.
The ratio of dissolved cadmium (Cd) to phosphate (PO4) in the subtropical coastal area of Ishigaki Island, Okinawa, Japan, was investigated. Twenty vertical seawater samplings were carried out once a month from May 2008 to January 2010. In order to examine how the Cd/PO4 ratio in seawater varies with the oceanographic conditions (i.e., the water temperature–salinity characteristics), the water masses at the study sites were classified into two types: group 1 with a water temperature of >25°C and a salinity range of 34.0–34.4, and group 2 with a water temperature of <25°C and a salinity of >34.4. A different phytoplankton assemblage was observed in each water mass defined. Different Cd/PO4 ratios were obtained for the two water mass types, due to the differences between the types in terms of the environmental conditions such as the water temperature–salinity (T–S) characteristics and phytoplankton assemblages, as well as possible variations in the concentrations of dissolved iron, zinc, manganese, and CO2 in seawater in each water mass.  相似文献   

20.
Member States of the European Union and the Mediterranean Regional Sea need to elaborate national strategies for coastal management according to ICZM principles and to undertake national stock-taking, which must consider major actors, laws and institutions influencing the management of their national coastal zone. However, different approaches to coastal management and defence and various degrees of development and implementation of national ICZM strategies can be found. The research presented in this article aims to analyze the different situations and to contribute to the further development of a common approach in terms of methodology to establish stakeholder and users participation in ICZM. An extensive survey was conducted in five pilot sites along the European Mediterranean coastal zone (Greece, Italy and France) show beach visitors’ perception of ICZM, coastal erosion and coastal defence systems, and beach visitors’ Willingness To Pay (WTP) for beach defence. The survey yielded important information for coastal and beach managers. Surprisingly, the level of awareness about generic Coastal Zone Management was found to be rather low in all regions except Riccione Southern beach, Emilia-Romagna Region. In the Languedoc-Roussillon Region, this is justified by the fact that most of the respondents were not local people or beach visitors (other than recreational day-visitors). As regards coastal erosion it appears significant that, despite the lack of awareness demonstrated overall by stakeholders in the Region of East Macedonia and Thrace, visitors respond very positively to definitions and show awareness of the erosion process in their coastal system. In conclusion, in order to raise public awareness about ICZM, erosion and coastal defence systems, it is suggested that education, training and public awareness should be promoted as well as identification of local needs for the implementation of specific demand-driven studies.  相似文献   

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