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Lagoon
Kinds of Lagoon Terms modified by Lagoon Selected AbstractsA prime inference on genetic diversity (RAPDs) in the marine fish Atherinella brasiliensis (Teleostei, Atherinopsidae) from Southern BrazilACTA ZOOLOGICA, Issue 2 2010Maria Cristina Da Silva Cortinhas Abstract Da Silva Cortinhas, M. C., Glienke, C., Prioli, A. J., Noleto, R. B., Matoso, D. A. and Cestari, M. M. 2010. A prime inference on genetic diversity (RAPDs) in the marine fish Atherinella brasiliensis (Teleostei, Atherinopsidae) from Southern Brazil. ,Acta Zoologica (Stockholm) 91: 242,248 As a result of the importance of Atherinella brasiliensis in estuarine environments, random amplified polymorphic DNA (RAPD) markers were used to verify the genetic diversity in A. brasiliensis from two different places in Paranaguá Bay (Paraná State) and one from the Conceição Lagoon (Santa Catarina State). Cytogenetic data have shown a high karyotypic diversity in some populations, although in others this peculiarity demonstrates rearrangements such as heterochromatinization. In the present study, a low level of genetic structuring between the samples from Conceição Lagoon compared with the others was observed through principal coordinate analysis (PCO), analysis of molecular variance and Mantel test according to 79 RAPD markers. As this specie does not perform horizontal migration and the individuals of Conceição Lagoon are isolated, three hypotheses are proposed to explain the results: (i) similar environments may show homogeneous populations not depending on the geographical distance, (ii) because vicariant events that formed the bays occurred in a recent period, the fragmentation effects over the structuring of the genetic diversity may still be low and not totally detectable by the RAPD technique and (iii) the isolation time or the number of generations may not be enough to promote a possible differentiation and genetic structuring between the specimens of these three places. The specimens of these places present a low level of differentiation and genetic structuring so we can consider them as a unique homogeneous population. [source] Regional differences in kelp-associated algal assemblages on temperate limestone reefs in south-western AustraliaDIVERSITY AND DISTRIBUTIONS, Issue 6 2003Thomas Wernberg Abstract.,Ecklonia radiata (C. Agardh) J. Agardh kelp beds , a characteristic feature of the nearshore environment along the south-west Australian coastline , contribute significantly to the coastal biodiversity in temperate Australia, yet, little is known about the organization of these macroalgal assemblages. By compiling existing and new data sets from habitat surveys, we have characterized and compared the structure of kelp-associated macroalgal assemblages in three regions (Marmion Lagoon, Hamelin Bay and the marine environment neighbouring the Fitzgerald River National Park) across more than 1000 kilometres of the south-west Australian coastline. 152 macroalgal taxa had been recognized within the three regions and this is in the range of species richness reported from other Australian and African kelp beds. The kelp-associated algal assemblages were regionally distinct, 66% of all taxa were only found in one region and only 17 taxa were found in all three regions. Adjacent regions shared an additional 13,15 taxa. The regional shifts in assemblage structure were evident in species composition of both canopy and understorey. The organization of assemblages followed a spatial hierarchy where differences in assemblage structure were larger among regions (hundreds of kilometres apart) than among sites within regions (kilometres apart) and differences among sites within region were larger than differences among quadrats within sites (metres apart). Despite this hierarchy each level of nesting contributed approximately the same to total variation in assemblage structure and these spatial patterns were stronger than temporal differences from seasons to 2,3 years. Our results suggest that local and small-scale processes contribute considerably to heterogeneity in macroalgal assemblages throughout south-western Australia, and, in particular, our results are consistent with E. radiata exerting a strong influence on macroalgal assemblage structure. Further, our study contradicts the existence of a general south-west Australian kelp assemblage, although a few species may form the core of E. radiata associations across regions. [source] Actinorhodopsins: proteorhodopsin-like gene sequences found predominantly in non-marine environmentsENVIRONMENTAL MICROBIOLOGY, Issue 4 2008Adrian K. Sharma Summary Proteorhodopsins are light-energy-harvesting transmembrane proteins encoded by genes recently discovered in the surface waters of the world's oceans. Metagenomic data from the Global Ocean Sampling expedition (GOS) recovered 2674 proteorhodopsin-related sequences from 51 aquatic samples. Four of these samples were from non-marine environments, specifically, Lake Gatun within the Panama Canal, Delaware Bay and Chesapeake Bay and the Punta Cormorant Lagoon in Ecuador. Rhodopsins related to but phylogenetically distinct from most sequences designated proteorhodopsins were present at all four of these non-marine sites and comprised three different clades that were almost completely absent from marine samples. Phylogenomic analyses of genes adjacent to those encoding these novel rhodopsins suggest affiliation to the Actinobacteria, and hence we propose to name these divergent, non-marine rhodopsins ,actinorhodopsins'. Actinorhodopsins conserve the acidic amino acid residues critical for proton pumping and their genes lack genomic association with those encoding photo-sensory transducer proteins, thus supporting a putative ion pumping function. The ratio of recA and radA to rhodopsin genes in the different environment types sampled within the GOS indicates that rhodopsins of one type or another are abundant in microbial communities in freshwater, estuarine and lagoon ecosystems, supporting an important role for these photosystems in all aquatic environments influenced by sunlight. [source] Relation between metal concentration in water and metal content of marine mussels (Mytilus galloprovincialis): Impact of physiology,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2008Stellio Casas Abstract The present study constitutes an in situ investigation of metal kinetics within soft tissue of mussels (Mytilus gallo-provincialis), which solves the problem of the decoupling of the effect of animal physiology and metal bioavailability in water. Field experiments were conducted to measure uptake and elimination kinetics for four metals (Hg, Pb, Cd, and Cu) in three Mediterranean sites with different contamination and nutritive levels. At each site, metal concentrations were monitored in soft tissues of mussels and in the surrounding waters. The experimental conditions were completely characterized: Lazaret Bay (located between Nice and Marseille, France) is a hot spot for Hg (6.3 ng/L) and Pb (163 ng/L) concentrations and is an oligotrophic, stable site; Bages Lagoon (located to the west of Montpellier, France) is particularly contaminated by Cd (1.5 ng/L) and Cu (1.5,g/L) and is a mesotrophic site where variability of trophic and physicochemical parameters is significant; and Port-Cros Island (located in the Hyeres National Park, France) is considered to be a reference site. Those kinetics permit us to decouple physiological, chemical, and environmental interactions. After normalizing mussel metal content for similar physiological conditions, application of the local weighted regression (LOWESS) statistical treatment shows a parallelism between the time trends of metal concentrations in the bivalve and metal concentrations in water. The results enabled us to obtain in situ kinetic parameters and realistic bioaccumulation factors. Their logarithmic values were 4.6 for Hg, 4.3 for Pb, 4.9 for Cd, and 3.9 for Cu. The importance of physiological processes such as spawning is discussed as a factor influencing the bioaccumulation factor. This information may be useful in refining monitoring tools for risk assessment and, more generally, in environmental management strategies. [source] Ecological risk assessment of persistent toxic substances for the clam Tapes philipinarum in the lagoon of venice, italyENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2004Christian Micheletti Abstract Because of contamination of sediments of the Lagoon of Venice, Italy, by inorganic pollutants (e.g., arsenic, cadmium, chromium, copper, lead, mercury, nickel, and zinc) and organic pollutants (e.g., polychlorobiphenyls), as well as the ecological and economical relevance of the edible clam Tapes philipinarum, an ecological risk assessment was undertaken to ascertain the extent of bioaccumulation that would pose a significant risk. Risk was estimated by means of toxic units and hazard quotient approaches, by comparing the exposure concentration with the effect concentration. Clam exposure was estimated by applying previous results based on bioaccumulation spatial regression models. In addition, a comparison was made between sum of dioxin-like polychlorinated biphenyl (PCB) congeners and total PCB bioaccumulation provided by spatial regression models and by a partitioning model. The effect concentrations were calculated as tissue screening concentrations, as the product of pollutant sediment quality criteria and the bioaccumulation factor. Finally, the cumulative risk posed by selected inorganic pollutants and total PCBs was estimated and a map of risk was drawn. The resulting chemicals of potential ecological concern were mercury, cadmium, arsenic, and nickel, as well as, to a lesser extent, total PCBs. [source] Variation of metallothionein and metal concentrations in the digestive gland of the clam Ruditapes decussatus: Sex and seasonal effectsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2001Maria A. Serafim Abstract Metallothionein (MT) and metal (Cd, Cu, and Zn) concentrations were determined in the digestive gland of male and female Ruditapes decussatus. Clams were collected monthly during the period of sexual development, from June to September, at two different sites of a coastal lagoon, the Ria Formosa Lagoon, on the south coast of Portugal. The MT concentrations were determined in the heat-treated cytosolic fraction of the digestive gland of both male and female clams. Total metal (Cd, Cu, and Zn) concentrations in the heat-treated cytosol of the digestive gland were also determined in both sexes. The MT and metal concentrations in the digestive gland were not sex dependent in this species. Therefore, these results suggest that random samples can be used to determine MT and metal concentrations in the digestive gland of R. decussatus. Seasonal and site-specific dependency, however, were detected for MT, Cd, and Cu concentrations. The maximum concentration levels of MT, Cd, and Cu were detected in July and August for both sexes in the same area. Zinc concentrations, however, did not show marked seasonal variations, indicating that this species is able to regulate zinc concentrations. The highest MT concentrations were significantly related to the highest metal concentrations. [source] Fisheries of two tropical lagoons in Ghana, West AfricaFISHERIES MANAGEMENT & ECOLOGY, Issue 6 2004H. R. Dankwa Abstract, The fisheries of two coastal lagoons, Keta and Songor, were studied as part of Ghana Coastal Wetlands Management Project (GCWMP) aimed at sustainable exploitation of wetland resources. Fish samples were obtained with seine nets and cast net as well as from local fishermen. Water quality parameters (pH, dissolved oxygen, temperature and turbidity) were similar in the two lagoons, except for salinity, which was significantly different (P < 0.001). Despite their close geographical proximity, the two lagoons supported different fish assemblages with the blackchin tilapia, Sarotherodon melanotheron Rüppell, and the redchin tilapia, Tilapia guineensis (Bleeker), being the most important commercial fishes in both lagoons. The number of individuals for each species in Songor Lagoon were far more abundant, with densities several orders of magnitude higher than in Keta Lagoon. However, both species were significantly larger (P < 0.01) in the latter [15,121 and 25,157 mm standard length (SL)] than in the former lagoon (30,102 and 15,95 mm SL) for S. melanotheron and T. guineensis respectively. Over-fishing, use of small-size mesh nets, limited mixing of marine and fresh water were some of the factors limiting fish production in both lagoons. [source] Diel variation in the seagrass ichthyofaunas of three intermittently open estuaries in south-eastern Australia: implications for improving fish diversity assessmentsFISHERIES MANAGEMENT & ECOLOGY, Issue 2 2001S. P. Griffiths Diel variation in the ichthyofaunas associated with Zostera capricorni Ascherson was investigated in three intermittently open estuaries in the Illawarra region, New South Wales. Each estuary showed differing diel shifts in fish assemblages, which appeared to be related to estuary size. In the largest estuary (Lake Illawarra) significantly more species were caught during the night than the day for all months. In contrast, there was little diel variation in the fish assemblages at Werri Lagoon and Shellharbour Lagoon, although many species were only caught during the night at both estuaries. The distinct diel changes at Lake Illawarra was thought to be attributable to the relatively deep channels adjacent to the seagrass beds which are better habitats for larger fishes compared with the shallow sand bars without deep channels throughout the two smaller estuaries. The composition of fish species within the three estuaries were significantly different, although each assemblage was characterised by large numbers of small-sized fish (<100 mm FL) indicating the importance of intermittently open estuaries as fish habitats. It was concluded that night sampling provided a more complete picture of the ichthyofaunas associated with Z. capricorni. As a result, inclusion of night sampling in fish diversity assessments would increase the chance of catching diurnally rare species and therefore attain a better representation of the true community structure. [source] Lagoon,tidal flat sedimentation in an epeiric sea: Proterozoic Bhander Group, Son Valley, IndiaGEOLOGICAL JOURNAL, Issue 2 2001Chandan Chakraborty Abstract The Bhander Group, the uppermost stratigraphic unit of the Proterozoic Vindhyan Supergroup in Son Valley, exhibits in its upper part a 550,m thick, muddy siliciclastic succession characterized by features indicative of deposition in a wave-affected coastal, lagoon,tidal flat environment suffering repeated submergence and emergence. The basic architecture of the deposit is alternation of centimetre- to decimetre-thick sheet-like interbeds of coarser clastics (mainly sandstone) and decimetre-thick mudstones. The coarser interlayers are dominated by a variety of ripple-formed laminations. The preserved ripple forms on bed-top surfaces and their internal lamination style suggest both oscillatory and combined flows for their formation. Interference, superimposed, ladder-back and flat-topped ripples are also common. Synsedimentary cracks, wrinkle marks, features resembling rain prints and adhesion structures occur in profusion on bed-top surfaces. Salt pseudomorphs are also present at the bases of beds. The mudstone intervals represent suspension settlement and show partings with interfaces characterized by synsedimentary cracks. It is inferred that the sediments were deposited on a coastal plain characterized by a peritidal (supratidal,intertidal) flat and evaporative lagoon suffering repeated submergence and emergence due to storm-induced coastal setup and setdown in addition to tidal fluctuations. The 550,m thick coastal flat succession is surprisingly devoid of any barrier bar deposits and also lacks shoreface and shelfal strata. The large areal extent of the coastal flat succession (c. 100,000,km2) and its great thickness indicate an extremely low-gradient epeiric basin characterized by an extensive coastal flat sheltered from the deeper marine domain. It is inferred that the Bhander coastal flat was protected from the open sea by the Bundelkhand basement arch to the north of the Vindhyan basin, instead of barrier bars. Such a setting favoured accumulation of a high proportion of terrigenous mud in the coastal plain, in contrast to many described examples from the Proterozoic. Copyright © 2001 John Wiley & Sons, Ltd. [source] Red-gartered Coot Fulica armillata feeding on the grapsid crab Cyrtograpsus angulatus: advantages and disadvantages of an unusual food resourceIBIS, Issue 1 2008GERMÁN O. GARCÍA The behaviour of Red-gartered Coots feeding on an unusual food source was examined at Mar Chiquita Coastal Lagoon, Argentina. The grapsid crab Cyrtograpsus angulatus made up all observed prey items, and 61% were small. Both handling and foraging duration increased with the size of captured crabs, but foraging efficiency decreased. Crab availability affected both the dive duration of the Coots and their foraging decisions with regard to prey-size selection. Two species of gull were observed kleptoparasitizing Coots, especially when the Coot was handling medium or large crabs. Feeding by Coots on Cyrtograpsus angulatus has not been previously documented and may be a feeding innovation. Our estimations suggest that Coots were foraging optimally, since smaller crabs were more energetically profitable. [source] The sediments of the venice lagoon (Italy) evaluated in a screening risk assessment approach: Part I,application of international sediment quality guidelinesINTEGRATED ENVIRONMENTAL ASSESSMENT AND MANAGEMENT, Issue 3 2007Sabine E Apitz Abstract Although it generally is agreed on in the scientific community that an evaluation of sediment quality solely based on total contaminant levels should be regarded only as a 1st tier or 1 LOE in a WOE framework, not all regulatory frameworks follow this approach. As will be discussed later, dredged material disposal in Venice Lagoon currently is regulated based upon the use of regionally developed SQGs as strict pass/fail criteria. The implications of this policy upon the management of the lagoon are under investigation, but studies on contaminant mobility and bioavailability and on sediment-related effects on biota and exposure (bioassays, biomarkers, bioaccumulation, biomagnification) having the characteristics (duration, number of sites and samples, frequency, number of chemicals and endpoints, etc.) to properly support (e.g., preliminary and/or detailed quantitative risk assessment) decisions on a basin scale have been carried out only recently in the Venice Lagoon (Thetis 2003; Losso et al. 2004; Carrer et al. 2005; Thetis 2005c). [source] The shallow flow equations solved on adaptive quadtree gridsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 6 2001A. G. L. Borthwick Abstract This paper describes an adaptive quadtree grid-based solver of the depth-averaged shallow water equations. The model is designed to approximate flows in complicated large-scale shallow domains while focusing on important smaller-scale localized flow features. Quadtree grids are created automatically by recursive subdivision of a rectangle about discretized boundary, bathymetric or flow-related seeding points. It can be fitted in a fractal-like sense by local grid refinement to any boundary, however distorted, provided absolute convergence to the boundary is not required and a low level of stepped boundary can be tolerated. Grid information is stored as a tree data structure, with a novel indexing system used to link information on the quadtree to a finite volume discretization of the governing equations. As the flow field develops, the grids may be adapted using a parameter based on vorticity and grid cell size. The numerical model is validated using standard benchmark tests, including seiches, Coriolis-induced set-up, jet-forced flow in a circular reservoir, and wetting and drying. Wind-induced flow in the Nichupté Lagoon, México, provides an illustrative example of an application to flow in extremely complicated multi-connected regions. Copyright © 2001 John Wiley & Sons, Ltd. [source] Effects of atmospheric circulation on ice conditions in the southern Baltic coastal lagoonsINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 13 2001Józef Piotr Girjatowicz Abstract Relationships between atmospheric circulation patterns and ice conditions in the southern Baltic coastal lagoons were explored. Ice data consisted of number of ice days (L) and duration of ice season (S) in the Szczecin Lagoon (off Karnin), the Puck Bay (off Puck) and the Vistula Lagoon (off Krasnoflotskoye) from 1950/1951 to 1989/1990. Atmospheric circulation patterns for the period studied were extracted from Lity,ski's ,Calendar of atmospheric circulation types' developed at the Institute of Meteorology and Water Management (IMWM). A circulation pattern was identified by three numerical parameters: the zonal circulation index, the meridional circulation index, both pertaining to a zone delimited by coordinates 40,60°N, 0,35°E, and the surface pressure index for Warsaw. The number of days with individual atmospheric circulation patterns occurring from October to March was calculated. Subsequently, the selected patterns were combined by wind direction sectors and several month-long periods that most closely correlated with ice conditions. The highest linear correlation coefficients (r>0.8) were obtained for the relationship between the number of days with winds from the east from December to February and December to March and the winter number of ice days (L). Somewhat higher were multiple correlation coefficients with winds from the east and west as circulation type predictors. Slightly lower correlation coefficients for the sectors and circulation periods mentioned were obtained for the duration of the ice season (S), although some of the coefficients were significant even at the probability level of ,=0.01. Higher correlation coefficients were obtained for correlations involving ,cold' circulation patterns (sector NE+E+SE winds) and ice conditions than for those involving ,warm' patterns (sector SW+W+NW). Copyright © 2001 Royal Meteorological Society [source] Roman Navigation in Venice Lagoon: the Results of Underwater ResearchINTERNATIONAL JOURNAL OF NAUTICAL ARCHAEOLOGY, Issue 2 2010Marco D'Agostino Venice lagoon formed part of a network of inland waterways used for navigation in the northern Adriatic, an almost continuous system of lakes, river-mouths and canals, at least partly pre-Roman in origin. The fossae which cross the present lagoon are the continuation of a complex system of natural watercourses and artificial canals between Ravenna and Aquileia. Two Roman buildings discovered on the present San Felice canal could be interpreted as providing navigational assistance at points linking the sea and inland routes. © 2009 The Authors [source] In-situ Corrosion Studies on Wrecked Aircraft of the Imperial Japanese Navy in Chuuk Lagoon, Federated States of MicronesiaINTERNATIONAL JOURNAL OF NAUTICAL ARCHAEOLOGY, Issue 1 2006Ian D. MacLeod A preliminary in-situ corrosion survey of the submerged Japanese WWII aircraft in Chuuk Lagoon, in the Federated States of Micronesia, has provided information on the way in which the wrecks interact with the marine environment. The aircraft are characterised by a lack of encrusting marine organisms and are clearly identifiable. The values of pH and the corrosion potentials vary with depth and the voltage depends on the composition of the underlying metal alloys. It is possible that with additional data from these non-destructive methods techniques it will be possible to provide marine archaeologists with appropriate diagnostic tools. © 2006 The Author. [source] Effects of Submerged Aquatic Vegetation on Macrozoobenthos in a Coastal Lagoon of the Southwestern AtlanticINTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 1 2007Rafael Arocena Abstract The freshwater-dominated part of Rocha coastal lagoon recently experienced sudden colonization by submerged aquatic vegetation (SAV). Macrophytes may be beneficial or detrimental for the zoobenthos, and both assemblages may in turn affect the food availability for birds and fishes. With the aim of evaluating the effect of SAV on water conditions and on the composition, abundance and diversity of macrozoobenthos, vegetated areas (V, up to 500 g DW m,2) were compared with vegetation-free areas (N). The benthic abundance was higher in V (up to 5000 ind m,2) than in N (up to 2200 ind m,2). Species richness and abundance of amphipods, gastropods and chironomids were also higher at V compared with N. Conversely, the abundance of Tanais stanfordi (Crustacea), Erodona mactroides (Bivalvia) and Laeonereis culveri (Polychaeta), and the Shannon diversity were higher at N. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Abundance, Population Structure and Production of Scrobicularia plana and Abra tenuis (Bivalvia: Scrobicularidae) in a Mediterranean Brackish Lagoon, Lake Ichkeul, TunisiaINTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 4 2005Caterina Casagranda Abstract Abundance, growth and production of the deposit-feeding bivalves were studied in the Ichkeul wetland, northern Tunisia, from July 1993 , April 1994. Scrobicularia plana(Da Costa, 1778) occurred at annual mean densities (biomasses) of 299 ± 65 to 400 ± 100 individuals/m2 (22.54 ± 3.00 to 34.27 ± 3.96 g ash-free dry mass (AFDM)/m2) depending on the study area. The annual mean density of Abra tenuis(Montagu, 1803) amounted to 640 ± 74 individuals/m2 during the whole study period, in contrast the biomass rose from 2.87 g AFDM/m2 in July to 10.29 g AFDM/m2 in April. Both species were largely dominated by age class I. Although not very successful, recruitment presented a two-period pattern: the main period at the beginning of spring, and a secondary one in late summer/autumn. S. plana rarely exceeded 40 mm and lived for only 2 years, while most individuals of A. tenuis lived for only 15,18 months growing to a length of 12 mm. The annual bivalve deposit-feeder production for the whole lagoon system (90 km2) was 8.24 g AFDM/m2 (5.26 g C/m2, 0.65 g N/m2). The annual P/ ratio was about 0.4 and therefore in the same order of magnitude as estimates from other brackish coastal waters. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Variability of Organic Matter Processing in a Mediterranean Coastal LagoonINTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 5-6 2004Margarita Menéndez Abstract The spatial variability of plant organic matter processing was studied experimentally in a shallow coastal lagoon (Tancada lagoon, average depth: 37 cm, area: 1.8 km2) in the Ebro River Delta (NE Spain). To determine the effect of hydrology and sediment characteristics on plant organic matter processing, leaves of Phragmites australis at the end of its vegetative cycle and whole plants of Ruppia cirrhosa(Petagna) Grande, just abscised, were enclosed in litter bags. Two different mesh sizes (100 ,m and 2 mm) were used to study the effect of macroinvertebrates on decomposition. The bags were placed in the water column and approximately 15 cm above the sediment at 6 different locations in the lagoon. The experiment was performed twice, in autumn-winter and spring-summer. The effect of macroinvertebrates on decomposition rate was not significant in Tancada lagoon. Breakdown rates showed spatial differences only in spring-summer. In the autumn-winter experiment, the effect of strong wind masked the effects of environmental variables and hydrology on decomposition rate. In the spring-summer experiment, characterised by high stability of the water column, dissolved inorganic nitrogen (DIN) concentration in the water column and organic matter in the sediment were the main factors determining the variability of organic matter processing. A positive relationship was calculated between P. australis decomposition rate and dissolved inorganic nitrogen in spring-summer (r2 = 0.92, p < 0.001). (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Water management tasks in the summer polders of the Nemunas lowland,IRRIGATION AND DRAINAGE, Issue 2 2006Antanas Lukianas plaine d'inondation; polders d'été; gestion des eaux Abstract Surplus water during floods as well as the low level of the soil surface determine the complicated ecological, economic and demographic conditions in the Nemunas delta. Subsequently, it leads to different types and intensity of use of farmland as well as different methods of water regime regulation: summer or winter type polders. The building of 17 summer polders in the 32,500,ha floodplain area was a compromise, seeking to improve farming conditions and maintain the stability of the flood regime and ecology in the delta. Field measurements and mathematical modelling were carried out. As study results have shown, grass yield losses due to flooding depend on the distribution of water levels and flood duration in the summer polders. Relative damage to agriculture is insignificant and makes up only 10,15% of the total amount of flood damage in the Nemunas lowland. The field measurements and hydraulic and mathematical modelling of flow and sediment regime as well as study of flooding and changed farming conditions also show that it is possible to reduce the height of floods and economic and ecological damage. Rearrangement of the system of protective dikes, regulation of the main river canal and water/sedimentation regime with the help of pumping stations, decrease of pollutant migration into the Curonian Lagoon and Baltic Sea, and recreation of natural meadows are important in that case. Copyright © 2006 John Wiley & Sons, Ltd. Des eaux excédentaires en période de crues et un faible niveau du sol déterminent les conditions écologiques, économiques et démographiques complexes du delta du fleuve Nemunas. En particulier, des types et intensités différentes dans l'utilisation des terres arables, ainsi que des méthodes différentes de régulation du régime des eaux: polders d'été ou d'hiver. La construction de 17 polders d'été sur 32 500,ha de plaine d'inondation a été une solution de compromis pour améliorer l'agriculture et maintenir la stabilité du régime des crues et de l'écologie du delta. Des mesures de terrain et des modèles mathématique ont été réalisés. D'après les résultats des études, les pertes de récolte d'herbe dûes aux crues dépendent de la distribution des niveaux d'eau et de la durée de la crue dans les polders d'été. L'impact négatif sur l'agriculture est négligeable et ne représente que 10 à 15% des dommages totaux dus aux crues dans le delta du fleuve Nemunas. Les mesures de terrain et la modélisation hydraulique et mathématique de l'écoulement et de la sédimentation, ainsi que l'analyse des crues et des modifications de production agricole, prouvent également qu'il est possible de réduire la hauteur des crues et de diminuer ainsi les dommages économiques et écologiques. Dans ce cas, il convient de réorganiser le système des digues de protection, de réguler le chenal principal du fleuve et le régime de sédimentation des eaux à l'aide de stations de pompage, de réduire les déversements polluants dans la lagune Curonian et la mer Baltique, et de régénérer des pâturages naturels. Copyright © 2006 John Wiley & Sons, Ltd. [source] Assessment of potential ecological disruption based on heavy metal toxicity, accumulation and distribution in media of the Lagos LagoonAFRICAN JOURNAL OF ECOLOGY, Issue 4 2007Otitoloju A. Adebayo Abstract Toxicity evaluations of heavy metals against three benthic animals, Tympanotonus fuscatus, Clibanarius africanus and Sesarma huzardi of the Lagos Lagoon were carried out under laboratory conditions. On the basis of the 96hLC50 values, Cd was found to be the most toxic metal tested followed by Cu, Zn and Pb, in a descending order of toxicity against T. fuscatus and S. huzardi; however, against C. africanus, Cu was the most toxic followed by Cd, Zn and Pb (least toxic). The determination of the metal concentrations in the water column and sediment of the Lagos Lagoon revealed that these media of the lagoon contained measurable concentrations of heavy metals but the levels were still several folds lower than the concentrations that will cause 50% mortality of exposed animals under laboratory conditions. The significance of the observed differences between the 96hLC50 values of the test metals, the concentration of heavy metals detected in tissues of field animals and ambient levels of the metals in the Lagos lagoon were discussed in relation to the protection of aquatic lives and potential public health risks. The need to verify the possibilities of synergistic interactions between the constituent metals when acting jointly against the exposed animals was recommended. Resume On a procédé en laboratoire à des évaluations de la toxicité des métaux lourds chez trois animaux benthiques, Tympanotonus fuscatus, Clibanarius africanus et Sesarma huzardi, du lagon de Lagos. Sur la base des valeurs de 96hLC50, on a trouvé que le Cd était le métal testé le plus toxique suivi par le Cu, le Zn et le Pb, en ordre de toxicité décroissant pour T. fuscatus et S. huzardi; cependant, pour C. africanus, le Cu était le plus toxique, suivi par Zn et Pb (le moins toxique). La détermination des concentrations de métaux dans l'eau et les sédiments du lagon de Lagos a révélé que ces milieux contenaient des concentrations mesurables de métaux lourds, mais que les niveaux étaient encore plusieurs fois plus bas que les concentrations qui causaient 50% de mortalité chez les animaux qui y étaient exposés en laboratoire. La signification des différences constatées entre les valeurs de 96hLC50 des métaux testés, la concentration des métaux lourds détectés dans les tissus des animaux du lagon et les niveaux observés dans le lagon ont été discutés en relation avec la protection de la vie aquatique et des risques potentiels pour la santé des personnes. On a recommandé de vérifier s'il est possible qu'il existe des interactions synergiques entre les métaux constituants lorsqu'ils agissent conjointement sur les animaux qui y sont exposés. [source] The occurrence and ecology of a marine hydrobiid mudsnail in the southern hemisphere: the Knysna Estuary, South AfricaAFRICAN JOURNAL OF ECOLOGY, Issue 3 2002R. S. K. BarnesArticle first published online: 6 AUG 200 Abstract Earlier published records of the gastropod Hydrobia from the warm temperate Knysna Lagoon on the Indian Ocean coast of South Africa are in error. Nevertheless, an animal hitherto identified as an Assiminea (Assimineidae) or as a Tomichia (Pomatiopsidae) is in fact a Hydrobia s.l., and it does occur intertidally within the Knysna system. The same species also occurs in salt pans in the cool temperate Great Berg Estuary on the Atlantic coast of South Africa. This extends the distribution of confirmed species of the dominant coastal hydrobiid mudsnails of the northern hemisphere into the southern hemisphere. H. knysnaensis (Krauss) occurs patchily at low density near the head of the Knysna Estuary in waters of low salinity. This appears to be a suboptimal habitat, and it is suggested that Hydrobia is restricted to this zone as a result of interference competition from potamidid mudwhelks and ocypodid crabs. The prevalence of potamidids and ocypodids in the tropics and in the temperate southern hemisphere may account for the rareness or absence of hydrobiids in these areas. Unlike its equally intertidal relative, the widespread North Atlantic/Arctic H. ulvae, H. knysnaensis develops directly like other Hydrobia. Résumé Les publications faisant état de la présence du gastéropode Hydrobia dans le lagon tempéré chaud de Knysna, sur la côte sud-africaine de l'océan Indien sont erronées. Néanmoins, un animal identifié jusqu'ici comme un Assiminea (Assimineidae) ou comme un Tomichia (Pomatiopsidae), est en fait un Hydrobia s.l. et il apparaît sur l'estran dans le système de Knysna. La même espèce se rencontre aussi dans des cuvettes saumâtres dans l'Estuaire de Great Berg, tempéré frais, sur la côte atlantique d'Afrique du Sud. Ceci élargit vers l'hémisphère sud la distribution d'une espèce confirmée des mollusques côtiers hydrobiinae dominants de l'hémisphère nord. H. knysnaensis (Krauss) se trouve çà et là, en faible quantité, au fond de l'estuaire de Knysna, dans des eaux de faible salinité. Ceci semble être un habitat sub-optimal, et on suggère qu'Hydrobia est confiné dans cette zone suite à la compétition avec les buccins potamilidae et avec les crabes ocypodidae. La prévalence de ces derniers sous les tropiques et dans la partie tempérée de l'hémisphère sud pourrait expliquer la rareté ou l'absence d'hydrobiidae dans ces régions. Contrairement à son parent H. ulvae, qui vit comme lui sur l'estran, très répandu dans l'Atlantique nord et dans l'Arctique, H. knysnaensis se développe directement, comme les autres Hydrobia. [source] The effect of temperature and somatic growth on otolith growth: the discrepancy between two clupeid species from a similar environmentJOURNAL OF FISH BIOLOGY, Issue 3 2006D. P. Fey Otolith growth rates of the early life stages of herring Clupea harengus (n= 472) and smelt Osmerus eperlanus (n= 348) collected in the Vistula Lagoon (Baltic Sea) during 1997,1999 were analysed. The larvae and early juveniles were not only collected in the same geographical area they were also of the same size (range 15,43 mm standard length, LS), similar ages and were collected during the same seasons (May to July). Although the two clupeid species experienced very similar environmental conditions, there were significant discrepancies in the analysed relationships. The otolith growth of larval and juvenile smelt was very strongly related to somatic growth while temperature had a minor effect. In herring, the effect of somatic growth, although clearly visible and statistically highly significant, was of less importance than temperature. Furthermore, variation in the otolith size and LS relationship was affected by temperature and somatic growth in both species, but the variance of otolith size at LS was higher for herring than for smelt. Although growth backcalculation from otoliths can presently be recommended as an appropriate method for use with both smelt and herring (despite possibly lower precision and accuracy with the latter), other methods referring directly to short-term increment width changes (e.g. marginal increment analysis) are recommended for smelt but not for herring. [source] Reproduction of Micropogonias funieri in a shallow temperate coastal lagoon in the southern AtlanticJOURNAL OF FISH BIOLOGY, Issue 2002D. Vizziano The white croaker Micropogonias furnieri, in the coastal Rocha Lagoon, spawned during 5 months, in late spring and summer. It was eurythermic (gonad growth at 12·5 to 25·5° C, spawning at 20 to 27° C) and mesoxic (living at 5·2 to 9·1 mg l -1). The spawning occurred in brackish (8,18 salinity), basic (c. 8 pH) and oxygenated (c. 8·0 mg l -1) waters. The temperature appeared to be an important environmental factor affecting the timing of reproduction. The size at first maturity (19,20 cm) was 11,12 cm lower than the reported for the Río de la Plata spawning area (Uruguay). Juveniles were observed throughout most of the year suggesting that the lagoon is also a nursery area. In Brazil, M. furnieri spawns in marine areas while in Uruguay it spawns in estuaries. This is the first time that a coastal lagoon of the subtropical and temperate western coast of the South Atlantic Ocean has been shown to be a spawning area of a marine species. [source] Quality Characteristics of Sea Bass Intensively Reared and from Lagoon as Affected by Growth Conditions and the Aquatic EnvironmentJOURNAL OF FOOD SCIENCE, Issue 2 2002E. Orban ABSTRACT: Sea bass (Dicentrarchus labrax) of commercial size free-living in the lagoon of Orbetello (Tuscany, Italy) and from intensive rearing were compared for proximate composition, essential and toxic metals, unsaponifiable lipids, and for the fatty acid profile of total, neutral, and polar lipids. Farmed sea bass had a total lipid content (10.57 ± 0.17g/100g) significantly higher (P , 0.001) than fish in the wild (1.78 ± 0.01 g/100g). Fish from either productive systems showed comparably high total polyunsaturated fatty acid levels and n-3/n-6 ratio values. Differences in the mineral content occurred among fish, particularly in the levels of mercury and selenium, significantly higher in those from the lagoon. [source] 81 Recent introduction of polysiphonia morrowii (ceramiales, rhodophyta) to punta arenas, chileJOURNAL OF PHYCOLOGY, Issue 2003M.S. Kim Polysiphonia morrowii (Rhodomelaceae, Rhodophyta) is abundant intertidally in spring in the Northwest Pacific. The species occurs in a large part of the North Sea and in Thau Lagoon, France, showing disjointed distributions, where the alga has been probably introduced recently. Using plastid protein-coding rbcL sequence data from specimens of P. morrowii and putatively related taxa, collected in Korea, Japan and Far-east Russia, and Chile, we tested the taxonomic position of each taxon. Pairwise divergence and topology of the sequences indicate that the Chilean taxon was identical to P. morrowii and was clearly separated from other related taxa from Chile. The results suggest that P. morrowii is recently anthropogenically introduced from the Northwest Pacific to Chile by boat or by transport with aquacultured organisms. Detailed observations of field-collected material will probably enable a more realistic evaluation of distribution of P. morrowii to be made in the Pacific Ocean. [source] Seasonal changes of antioxidant and oxidative parameters in the coral Pocillopora capitata on the Pacific coast of MexicoMARINE ECOLOGY, Issue 3 2010Marco A. Liñán-Cabello Abstract The physiological responses of the coral Pocillopora capitata to environmental conditions common in winter and summer were studied in 2007 during February,March (winter) and June,July (summer) at La Boquita reef (Manzanillo, Colima, Mexico). Shallow and deep sampling stations were established at different distances from a small jetty built next to the Juluapan Lagoon. We analyzed superoxide radicals () and lipid peroxidants (TBARS); the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), and glutathione-S-transferase (GST); chlorophyll a (Chl a), zooxanthellae density (ZD); and mycosporine-like amino acids (MAAs). Our results showed that the , TBARS, CAT, GST, MAAs, and Chl a, levels were significantly higher in summer (P < 0.05); no seasonal difference was found for GPx, GR or ZD. We found significant differences (P < 0.05) in winter only for Chl a and ZD at shallow sites and, in contrast, for at deeper sites. The results of this study indicate that increasing temperature and radiation associated with seasonal changes (from winter to summer), the efficiency of the enzymes GST, CR and GPX, and the production of MAAs together form a powerful mechanism for P. capitata to offset the detrimental effects of environmental change. [source] INTERACTIONS BETWEEN THE INDIAN RIVER LAGOON BLUE CRAB FISHERY AND THE BOTTLENOSE DOLPHIN, TURSIOPS TRUNCATUSMARINE MAMMAL SCIENCE, Issue 4 2002Wendy D. Noke Abstract Anecdotal reports from blue crab fishermen in the Indian River Lagoon (IRL), Florida suggested that bottlenose dolphins (Tursiops truncatus) followed their boats, and stole bait fish from crab pots soon after they were deployed. To investigate these reports, we made biweekly observations from IRL commercial crab boats from January 1998 to January 1999 (670 h). Only 2.8% of the 18,891 crab pots surveyed revealed evidence of dolphin/crab pot interaction. Dolphin interactions included: (1) begging at boats, (2) feeding on discarded bait fish, (3) engaging in crab pot tipping behavior, and (4) dolphin mortality from crab pot float line entanglement. Overall, 16.6% of the 1,296 dolphins sighted interacted with fishing boats. Seasonal trends were evident, with fishery interactions peaking in the summer. Crab pot interactions ranged from 0% to 36% of the traps checked daily. Different methods of securing the bait-well door and the role of trap locality were tested using a replicated experimental design. Results showed significant differences in successful bait removal by dolphins, among the degrees of door security (P < 0.001) and between trap location (P < 0.01). Thus, increased door security may help to reduce the negative impacts to the fishery and dolphins involved. [source] Isolation and characterization of eight microsatellite loci from Picnic seabream (Acanthopagrus berda)MOLECULAR ECOLOGY RESOURCES, Issue 4 2006C. T. JEAN Abstract Acanthopagrus berda (Sparidae) is abundant in estuaries and inshore waters of the tropical Indo-Pacific oceans. Because of the drastic decrease in the species' wild populations, there is an urgent need to understand its population structure. Eight microsatellite loci were isolated from A. berda. An analysis of 50 individuals from Tapeng Lagoon, southwestern Taiwan demonstrated a low degree of diversity. The allelic numbers ranged from nine to 20. The observed heterozygosity (HO) ranged from 0.28 to 0.64 (mean, 0.45). We also investigated the prospective value of the microsatellite primers to examine whether they were applicable to related taxa. [source] Indigenous Ecological Knowledge as Situated Practices: Understanding Fishers' Knowledge in the Western Solomon IslandsAMERICAN ANTHROPOLOGIST, Issue 3 2009Matthew Lauer ABSTRACT In this article, we draw on research among fisherfolk of Roviana Lagoon, Solomon Islands, to examine certain epistemological assumptions of the "indigenous knowledge" concept. We describe how approaches to knowledge in Roviana differ from prevailing models of knowledge that distinguish between cognitive aspects and other modalities of knowing. For many Roviana fishers, ecological knowledge is not analytically separated from the changing contexts of everyday activities such as navigating and fishing. Inspired by Roviana epistemologies, we argue that a practice-oriented approach provides a more sympathetic and informative theoretical framework for understanding knowledge and its role in contemporary marine-resource conservation efforts. The theoretical and methodological implications of the perspective are illustrated with examples from an ongoing marine conservation project in the western Solomon Islands that integrates indigenous knowledge, remote-sensing techniques, and Geographic Information System (GIS) technologies. [source] Hermaphrodite thinlip mullet Liza ramada (Risso, 1810) (Teleostei: Mugilidae) from Homa Lagoon (Izmir Bay-Aegean Sea)AQUACULTURE RESEARCH, Issue 10 2006Bahar Bayhan No abstract is available for this article. [source] | ||||||||||||||||||||||||||||||||||||||||