Helminth communities in eels Anguilla anguilla from Adriatic coastal lagoons in Italy

The composition and diversity of the total and intestinal component and infra-communities were determined in eels Anguilla anguilla from three shallow lagoons on the Adriatic coast of Italy to determine whether the helminth communities would differ in composition and structure from those in eels from lagoons on the Tyrrhenian coast. The lagoons differed in respect of their management regimes and the extent of freshwater influx. Both freshwater and marine species of helminths were found in the eels in all three lagoons, but the freshwater component was richer in Valle Figheri. A suite of three digenean eel specialist species occurred in all three lagoons, of which any two members dominated each community. This conferred a high degree of similarity between the communities of the three lagoons. The same three species also dominated helminth communities in eels in lagoons along the Tyrrhenian coast of Italy, and compositional similarity levels were similar within and between western and eastern groups. Species richness was higher in the component communities of the eels of the Adriatic lagoons when compared to the Tyrrhenian ones, but diversity and dominance indices were of a similar order of magnitude and range. Intestinal helminth communities were richer and more diverse in two of the Adriatic lagoons because the proportion of eels with zero or one helminth species was, unusually, in the minority. It was nevertheless concluded that infracommunity structure was similar in eels from both western and eastern lagoons and that the hypothesis that it would differ in Adriatic lagoons could not be supported. The findings provide further evidence of the similarity in composition and structure of helminth communities in eels from coastal lagoons throughout Europe.     

Proposals for macrophyte restoration in eutrophic coastal lagoons

Based on the comparison of environmental requirements forRuppia cirrhosa andPotamogeton pectinatus growth, macrophyteversus phytoplankton biomass and production features, and differences in hydrological and nutrient balances between Tancada lagoon (where macrophytes form dense beds) and Enca?izada lagoon (with no macrophytes at all), several proposals for macrophyte restoration are presented. The highest photosynthetic efficiency ofR. cirrhosa takes place at high irradiance and it grows over a wide range of salinity.P. pectinatus is better adapted to lower light intensity and salinity thanRuppia. R. cirrhosa transplanted from Tancada to Enca?izada was successful in enclosures, where light availability increased (μ=0.013 cm⁻¹), but not in open waters where light extinction coefficient was 0.032 cm⁻¹. Phytoplankton biomass (0.11–2.15 g C m⁻²) is much lower than macrophyte biomass (16–200 g C m⁻²) in Tancada lagoon. However, phytoplankton production (165 g C m⁻² yr⁻¹ in Tancada, 480 g C m⁻² yr⁻¹ in Enca?izada) is the same order of magnitude as macrophyte production (244–467 g C m⁻² yr⁻¹). Turnover rates are 0.3–0.9 day⁻¹ for phytoplankton and 1.2–2.5 yr⁻¹ for macrophytes. Phytoplankton and inorganic particles are responsible for high turbidity of the water in Enca?izada lagoon. Phytoplankton blooms in Enca?izada lagoon are supported by high freshwater inflows from rice field drains from May to November. The Q_s (seawater discharge)/Q_F (Freshwater discharge) ratios are, respectively, 0.24 and 0.48, which denotes a higher seawater influence in Tancada than in Enca?izada lagoon. Decreasing freshwater inputs to Enca?izada lagoon both in May and November thus allowing greater inputs of sea water, is proposed as the most effective way to restore this eutrophic coastal lagoon. The objective being to reduce nutrient loadings to the lagoon and phytoplankton in order to favour macrophyte re-colonization.     

Modulation of adenyl cyclase activity in the gills of Tapes philippinarum

Adenyl cyclase (AC) plays a pivotal role in cell signaling. The AC system of bivalves has received little attention so far, and our study has been addressed to the characterization of AC properties in the gills of T. philippinarum. The enzyme showed a Km value of 0.77 mM for ATP in the presence of 5 mM Mg2+; in the absence of agonists, it was poorly affected by GTP, while it was stimulated by GTPgammaS and GppNHp up to 14-fold and 4-fold, respectively. Similarly to other invertebrates, the enzyme activity was scarcely stimulated by forskolin. The receptor agonist serotonin (5-HT) significantly stimulated the AC activity, and the pharmacological profile of the 5-HT receptor/s was as follows: (+)butaclamol > dihydroergocryptine > methysergide > prazosin > yohimbine. The AC activity was assessed in vitro in the presence of tributyltin chloride and HgCl2, which reduced the AC activity only at the highest dose tested (10-100 microM). Our data indicate the presence of a membrane-bound AC in gill membranes of T. philippinarum, coupled to Gs proteins and to a specific class of 5-HT receptors. Such receptors show a pharmacological profile slightly different from that reported for 5-HT invertebrate receptors cloned so far.     

Hydrological characteristics of three North African coastal lagoons: insights from the MELMARINA project

Hydrological and hydrodynamic characteristics are important controls in all wetlands including coastal lagoons. Enhanced understanding of lagoon functioning can be obtained through the acquisition and interpretation of hydrological, meteorological and related data. The MELMARINA Project investigated links between hydrological and ecological conditions within North African coastal lagoons. It employed three primary sites: Merja Zerga in Morocco, Ghar El Melh in Tunisia and Lake Manzala in Egypt. Hydrological, meteorological and related data were acquired for these lagoons. Data included precipitation, evaporation, wind speed and direction, freshwater discharges into the lagoons, tides beyond the lagoons in the open sea, lagoon bathymetry and time series of lagoon water levels/depths. Data were acquired from secondary sources (including online archives) and targeted field survey and monitoring programmes. Interpretation of these data provides insights into the hydrological functioning of the lagoons and contributed to the modelling requirements of MELMARINA. The functioning of Merja Zerga is dominated by the exchange of water between the Atlantic and the lagoon. Large, tidally induced oscillations in water level are responsible for the inundation of extensive inter-tidal mudflats whilst the rapid replacement of water by exchanges with the sea diminishes the influence of freshwater inflows and winter rainfall. The smaller Mediterranean tides reduce the magnitude of lagoon–sea exchanges and result in much smaller water level oscillations within Ghar El Melh. As a result, this lagoon lacks the inter-tidal environments found within the Moroccan site and hydrodynamic conditions are more likely influenced by wind set up. Although freshwater inflows to Ghar El Melh are smaller than those in Merja Zerga, their effects, coupled with heavy winter rainfall, can persist due to longer residence times of water within the lagoon. Freshwater inflows are central to the functioning of Lake Manzala. Large discharges of relatively freshwater are provided by major drains which cross the Nile Delta. These influence lake water levels and are responsible for the freshwater conditions within large parts of the lake. The small tidal range of the eastern Mediterranean, coupled with constricted connections with the sea, reduces the influence of lake–sea exchanges and tidally induced water level oscillations within Lake Manzala. Guest editors: J. R. Thompson & R. J. Flower Hydro-ecological Monitoring and Modelling of North African Coastal Lagoons     

Application of remote sensing to site characterisation and environmental change analysis of North African coastal lagoons

This article describes the use of satellite imagery for identifying key environmental characteristics within three North African coastal lagoons (Merja Zerga, Morocco; Ghar El Melh, Tunisia and Lake Manzala, Egypt) and for detecting the major environmental changes within these environments. A combination of Landsat MSS, Landsat TM, Landsat ETM+ and ASTER imagery was acquired for the three sites for a period covering the last three decades (1972–2004). Following geometric correction and enhancement, the interpretation of the most recent image acquired for each of the three lagoons provides important insights into their current conditions. For Merja Zerga, these include the distribution of the largest channels which drain extensive inter-tidal mudflats and the two major depositional features associated with sources of freshwater. The distribution of marginal aquatic vegetation is highlighted as is the intensive use of the surrounding landscape for agriculture. Intensive agriculture around Ghar El Melh is also indicated. The influence of the Mejerda River, which was diverted away from the lagoon over 100 years ago, is shown to persist as a residual area of deltaic deposits in shallow water that has been eroded over time. Coastal processes including the direction of the alongshore sediment transport and the influence of engineering work associated with port construction can also be recognised. Within Lake Manzala, vegetated islands divide the lake into a series of sub-basins which can be clearly distinguished. The large influence of human activities within this lake can be identified and include reclamation for agriculture and the conversion of parts of the lake bed for fish farms. The historical images available for the three lagoons provide important insights into decadal scale changes, which have been greatest at Lake Manzala. Since the early 1970s large parts of the lake, in particular in the southwest where the shoreline has migrated northwards, have been reclaimed. Major engineering works, such as the El Salam Canal and road embankments, are shown to have resulted in significant lake change. The distribution of emergent vegetation within the lake has also changed. Classification of images for this lake into open water, vegetation and land enables the quantification of these changes. Between 1973 and 2003, the lake declined in area by approximately 50%. Changes at Merja Zerga over the last three decades include reconfiguration of the marine outlet and the expansion of the internal delta at the end of the Nador Canal. The images of this site clearly demonstrate the intensification of agriculture around the lagoon. The most marked changes evident within the images of Ghar El Melh concern the sand bars that separate the lagoon from the sea. Geomorphological processes operating within the coastal zone have resulted in the straightening of the bars with central sections migrating out towards the sea. Remote sensing is established as a promising application for detecting the quantitative surface cover changes in coastal lagoons and their near landscapes. Guest editors: J. R. Thompson & R. J. Flower Hydro-ecological Monitoring and Modelling of North African Coastal Lagoons     

Environmental influences on the qualitative and quantitative composition of phytoplankton and zooplankton in North African coastal lagoons

Within the framework of the international research project MELMARINA, seasonal dynamics of plankton communities in three North African coastal lagoons (Merja Zerga, Ghar El Melh, and Lake Manzala) were investigated. The sampling period extended from July 2003 to September 2004 with the aim of evaluating hydrological and other influences on the structure, composition and space-time development of these communities in each lagoon. Phytoplankton in Merja Zerga showed a quasi-permanent predominance of marine diatoms in the open sea station and in the marine inlet channel. Dinoflagellates were abundant in summer and early autumn in the marine inlet and extended into the central lagoon station. In Ghar El Melh, marine species (especially diatoms and dinoflagellates) dominated despite occasional winter inflows of freshwater. In Lake Manzala, freshwater species generally predominated and the planktonic communities were comparatively very diverse. Chlorophyceae contributed 39% of the total species recorded and diatoms and cyanophyceans were also common; the Dinophyceae, Euglenophyceae, Chrysophyceae and Cryptophyceae less so. Zooplankton communities in both Ghar El Melh and Merja Zerga were dominated by marine copepods. Rotifera, Copepoda, Ostracoda, and Cladocera were recorded in both lagoons as were meroplanktonic larvae of Polychaeta, Cirripedia, Mysidacea and Gastropoda and free living nematodes. Ghar El Melh was the more productive of these two lagoons with spring and early summer being the productive seasons. Zooplankton communities in Lake Manzala were generally dominated by rotifers and highest zooplankton abundances occurred in April (2003). Sampling stations near the marine inlets showed the highest diversity and the zooplankton communities showed considerable spatial variation within this large lagoon. The three lagoons represent very different water bodies contrasted strongly in terms of tidal effects and freshwater availability. Yet, there are some similarities in ecosystem structure. Space-time development of the plankton communities was similar especially in Merja Zerga and Ghar El Melh. Species abundances and specific diversities indicated that seasonal changes in salinity and nutrient concentrations were the main influential factors. Lake Manzala was the most productive lagoon and all the three sites supported toxic algal species. Relatively low plankton biomass in Merja Zerga and Ghar El Melh probably resulted from a combination of factors including highly episodic nutrient inputs, light suppression (by turbidity) and nutrient competition with benthic algae. Water quality variables were largely driven by the hydrological regime specific to each lagoon. Nutrient enrichment and, particularly for Lake Manzala, sea level rise threaten the sustainability of the planktonic ecosystems in all three lagoons. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Guest editors: J. R. Thompson & R. J. Flower Hydro-ecological Monitoring and Modelling of North African Coastal Lagoons     

The lichen flora of coastal saline lagoons in England

Abstract:The lichen flora associated with twenty saline lagoons in England is described. Though often scarce, lichens were present on shingle, miscellaneous stones, half-submerged concrete structures, retaining walls, salt marsh vegetation, wooden posts, and strand-line materials. Sites that had been modified by the activity of man often held richer assemblages than ones in a more natural condition. The lichen flora is a mixture of common-place species and maritime specialists. The large lagoon behind Chesil Beach, known as ‘The Fleet’, was the most important site surveyed. Many of the marine lichens present are typical of very sheltered coastlines. Caloplaca suaedae, found at two sites, is described as new to science.     

First evidence of cell division in circulating haemocytes from the Manila clam Tapes philippinarum

In the present study, we report on haemocyte distribution, determined by a Coulter Counter, in the clam Tapes philippinarum. In addition, cytoskeleton components of haemocytes were examined using specific probes for F-actin and alpha-tubulin. The mean number of circulating haemocytes was 5 (x10(6))cells/ml haemolymph. Two main haemocyte populations were found in the haemolymph: small cells, 2-3microm in diameter and 10-100fl in volume; and large cells, 6-10microm in diameter and 150-400fl in volume. Analysis of the haemocyte cytoskeleton revealed bundles of actin filaments oriented according to the cell major axis, and microtubules radiating from the microtubule-organizing centre in proximity of the nucleus. Interestingly, mitotic spindles were also found radiating from the microtubule-organizing centres, located at the spindle poles (centrosomes) of undifferentiated cells. On the basis of both our previous findings regarding circulating stem cells (Cima, F., Matozzo, V., Marin, M.G., Ballarin, L., 2000. Haemocytes of the clam Tapes philippinarum (Adams & Reeve, 1850): morphofunctional characterisation. Fish Shellfish Immunol 10, 677-693) and new information from the present study, we suggest that haemoblasts are able to divide in the haemolymph of T. philippinarum. To our knowledge, this is the first report of mitotic spindles in circulating haemocytes from a bivalve species.     

Molecular evolution and recombination in gender-associated mitochondrial DNAs of the Manila clam Tapes philippinarum

Doubly uniparental inheritance (DUI) provides an intriguing system for addressing aspects of molecular evolution and intermolecular recombination of mitochondrial DNA. For this reason, a large sequence analysis has been performed on Tapes philippinarum (Bivalvia, Veneridae), which has mitochondrial DNA heteroplasmy that is consistent with a DUI. The sequences of a 9.2-kb region (containing 29 genes) from 9 individuals and the sequences of a single gene from another 44 individuals are analyzed. Comparisons suggest that the two sex-related mitochondrial genomes do not experience a neutral pattern of divergence and that selection may act with varying strength on different genes. This pattern of evolution may be related to the long, separate history of M and F genomes within their tissue-specific "arenas." Moreover, our data suggest that recombinants, although occurring in soma, may seldom be transmitted to progeny in T. philippinarum.     

Regime shifts in vegetation composition of Baltic Sea coastal lagoons

Vegetation communities, morphometric and water quality variables were sampled in 62 undisturbed coastal lagoons along a natural land-uplift gradient in the northern Baltic Sea. The lagoons had a morphological inlet threshold reflecting habitat isolation (i.e. the diminished connectedness of the lagoon to the sea) and located in different parts of the archipelago (corresponding to altering wave exposure). We used indirect multivariate methods to find changes in vegetation composition, and axes derived from the analyses were used in correlation and stepwise multiple regression analyses together with environmental variables. Habitat isolation proved to be the strongest predictor for vegetation composition. To identify significant change-points we used a method, which detects regime shifts by accounting for differences in chronological series and gives a regime shift index. Significant shifts in habitat isolation, average depth and total nitrogen were followed by shifts in species variables (i.e. dominant species, cover and species richness) and salinity, total phosphorus and turbidity. Of the species, especially Chara tomentosa showed a shift of high magnitude. Also a shift in wave exposure mirroring position of lagoons in the archipelago structured the species, but this division was seen only for less isolated lagoons. Our results suggest that lagoons are primarily structured by habitat isolation forming two structurally different regimes: one of less isolated lagoons dominated by a diverse array of vascular plants and marine algae of both outer and inner archipelago characters, and one with isolated lagoons dominated by high vegetation cover and dominance of Chara. In addition, vegetation seemed to stabilize water quality in the isolated regime by reducing turbidity and phosphorus, indicating a potential feed-back mechanism and a shift in structuring disturbances from abiotic to biotic factors with habitat isolation.     

Anthropogenic disturbance and spatial heterogeneity of macrobenthic invertebrate assemblages in coastal lagoons: the study case of Pialassa Baiona (northern Adriatic Sea)

The distribution patterns of macrobenthic invertebrate assemblages at different spatial scales and in relation to natural and anthropogenic disturbance gradients were investigated in the Pialassa Baiona, a eutrophic and polluted brackish coastal lagoon located along the Italian coast of the northern Adriatic Sea. This coastal lagoon shows a complex physiography with several shallow water ponds and channels separated by discontinuous artificial embankments. Environmental variables and macrobenthic invertebrate assemblages showed higher heterogeneity at small spatial scale (i.e. within channels and ponds). Distinction between channels and ponds is only weakly supported by the distribution patterns of macrobenthic assemblages. Depth was the major factor in structuring benthic communities within ponds, while species distributions along the channels were strongly correlated with the anthropogenic disturbance gradient. Anthropogenic disturbance mainly affected species richness, which was inversely correlated with the organic carbon contents in the sediments and the water surface temperature, which is affected by the input of cooling water from two thermal power plants. Some opportunistic species, like the polychaetes Streblospio shrubsolii and Capitella capitata, were more abundant in the southern polluted areas. In particular, the abundance of S. shrubsolii significantly increased with organic carbon contents in the sediments and water surface temperature, while C. capitata was more abundant in the warmed sites and close to sewages. Conversely, the abundance of the amphipod Corophium insidiosum was inversely related to organic carbon contents.     

华北农业干旱监测与冬小麦估产研究

评估了基于植被光学厚度(VOD)和日光诱导叶绿素荧光(SIF)等植被广义光学特性构建的标准化植被指数(Z_VI)监测农业干旱的适用性;并采用VOD、SIF两种指数和土壤水分等环境变量的不同组合建立冬小麦估产的岭回归模型,以探究其对冬小麦产量的预报能力。结果表明：相较于Z_VOD,旬尺度Z_SIF对华北地区的农业干旱具有更好的监测能力,对重旱的正确检测率达到77%。Z_SIF能够有效反映干旱发生、发展直至减轻的演变过程,其低值区与站点记录的干旱空间分布相吻合。在华北地区南部,生长季C波段和Ku波段的VOD对冬小麦单产的预报能力优于SIF;利用VOD、SIF两种指数和环境变量的全变量模型取得了最好的估产精度,影响冬小麦产量估算精度的关键预测变量为生长高峰期的SIF。研究可为大范围农业干旱监测和粮食安全提供技术支持。     

Characterization of the waterbird communities wintering in Tunisian coastal lagoons

This article aims at studying wintering waterbirds in Tunisian coastal lagoons in order to support effective conservation measures. Species number and abundance of wintering waterbirds were assessed in January, each year from 2002 to 2007, in 10 lagoon sites belonging to four different lagoon systems. We counted 76 species and on average more than 120,000 birds per year, which represented more than 25% of the national population sizes. The most abundant taxonomic groups were waterfowls and waders, which also represented the highest species number. In general, the six most abundant bird species comprised collectively more than 77% of all birds counted. Considering all the studied lagoon systems collectively, for 13 species the lagoon systems should be considered as of international importance according the Ramsar Convention as they support regularly more than 1% of the populations. Only the lagoon system of the North held regularly more than 20,000 birds. The species abundances and species richness varied significantly among year and among lagoon systems. Based on our results we proposed priority conservation measures, these ecosystems being of major importance for wintering birds, at both national and international level.     

Resources and possibilities for exploitation of North Adriatic seaweeds

Suggestions for a small-scale exploitation of seaweeds in the northern Adriatic are given along with a survey of the fresh weight biomass and chemical composition of individual species. The intertidal is occupied by Fucus virsoides. In polluted sites, it is replaced by seasonal annuals. Cystoseira species are dominant in the upper subtidal and represent the major part of seaweed resources in this area. In polluted sites they are replaced by Halopteris scoparia and Dictyota dichotoma. Peaks in biomass were found in spring in the upper water layers and in early summer lower in the subtidal. The protein content of most species exhibited maxima in spring. Elevated values were found in plants from polluted and estuarine habitats.     

Meiofauna of silty sediments in the coastal area of the North Adriatic,with special reference to sampling methods

At five coastal silty sediment stations ranging in depth from 8 to 30 m, the abundance and composition of meiofauna were investigated. Three methods of sampling were used, i.e. Pfleger corer, Van Veen grab and SCUBA divers. Four samples per station were taken. The mean density of total meiofauna was 660 ± 109 ind. 10 cm². The main meiofauna group was Nematoda, the second abundant was Copepoda, and third was Kinorhyncha. Statistical tests showed significant differences in meiofaunal abundance between corer and grab samples, and between corer and divers samples.Differences in meiofauna abundance between stations were found.     

Bacterial interactions in the rhizosphere of seagrass communities in shallow coastal lagoons

Rooted phanerogam communities in the shallow intertidal and subtidal coastal zone represent productive and healthy ecosystems. Inorganic nutrients are assimilated into seagrass biomass. Much of the organic matter resulting from moribund seagrass is rapidly mineralized, principally by bacteria. The microbial community of the rhizosphere is also highly active due to the supply of organic matter released during photosynthesis. This active sediment community plays an important role through carbon, nitrogen and phosphorous cycling in maintaining the stability and productivity of seagrass meadows. Over the last two decades, however, seagrass meadows in European coastal areas have declined due to increasing pollution. As eutrophication advances a trasition occurs from rooted phanerogram dominated communities to planktonic algal blooms and/or cyanobacterial blooms. Such changes represent the decline of a stable, high biodiversity habitat to an unstable one dominated by a few species. These changes of community structure can occur rapidly once the internal nutrient and organic matter control cycles are exceeded. A field investigation was undertaken to establish the spatial distribution of bacterial populations of Zostera noltii colonized and uncolonized sediment in the Bassin d'Arcachon, France. Bacteria were enumerated using both plate count and MPN techniques for different functional groups as well as determining the total bacterial populations present. Nitrogen fixation, ammonification, sulphate reduction rates, as well as alkaline phosphatase activity were also determined. Colonization of the Z. noltii roots and rhizomes was studied by light and scanning electron microscopy. Results confirmed that higher bacterial populations were present in the rhizosphere of Z. noltii compared to uncolonized sediments. Furthermore, electron microscopy identified the rhizome as the main site of colonization for a diverse range of morphological groups of bacteria. Sulphate reducing bacteria were identified as the key group of bacteria involved in N-fixation in the rhizosphere of Z. noltii. The data will be discussed in relation to the role played by the rhizosphere microflora in supplying and mobilising nutrients in Z. noltii.     

Distribution and biodegradation potential of oil-degrading bacteria in North Eastern Japanese coastal waters

Abstract The distribution of oil-degrading microorganism in samples of surface water and sediment from North Eastern Japanese coastal waters was studied. Modified natural sea water (NSW) agar supplemented with emulsified crude oil (Arabian light, 5 g 1⁻¹) was used to enumerate oil-degrading bacteria. In addition, filtered samples were inoculated into NSW broth containing weathered crude oil. Incubation was carried out at 20°C for 7–10 days. Populations of oil-degrading microorganisms ranged from 3–230 CFU 100 ml⁻¹ in surface waters and 2.9 × 10³ to 1.2 × 10⁵ CFU g⁻ in sediment samples. Analysis of variance showed that oil-degraders were heterogenously distributed. Six mixed populations selected from 20 samples were studied to determine which of the constituent microflora were capable of crude oil biodegradation. Among 51 strains selected for identification, only 61% could be identified which formed 17 different bacterial species. Acinetobacter species (14 strains), Psychrobacter immobilis (9 strains) and Gram-positive cocci (10 strains) were the predominant types. Oil-degrading activity by various mixed populations (three each from water and sediment samples) was determined by using a conventional total weight reduction technique. Reduction in amount of various aliphatic and aromatic hydrocarbon substrates was verified using gas chromatography and high pressure liquid chromatography. Biodegradation of crude oil ranged from 35–58%. One mixed population of the sediment samples degraded more hydrocarbon (both aliphatic and aromatic) and the biodegradation of the aromatic hydrocarbon reached as high as 48%.