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Estuarine Waters (estuarine + water)
Selected AbstractsEvaluation of sorbent amendments for in situ remediation of metal-contaminated sedimentsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2010Seokjoon Kwon Abstract The present study evaluated sorbent amendments for in situ remediation of sediments contaminated with two divalent metals. A literature review screening was performed to identify low-cost natural mineral-based metal sorbents and high-performance commercial sorbents that were carried forward into laboratory experiments. Aqueous phase metal sorptivity of the selected sorbents was evaluated because dissolved metals in sediment porewater constitute an important route of exposure to benthic organisms. Based on pH-edge sorption test results, natural sorbents were eliminated due to inferior performance. The potential as in situ sediment amendment was explored by comparing the sorption properties of the engineered amendments in freshwater and saltwater (10 PPT salinity estuarine water) matrices. Self-assembled monolayers on mesoporous supports with thiols (Thiol-SAMMSÔ) and a titanosilicate mineral (ATSÔ) demonstrated the highest sorption capacity for cadmium (Cd) and lead (Pb), respectively. Sequential extraction tests conducted after mixing engineered sorbents with contaminated sediment demonstrated transfer of metal contaminants from a weakly bound state to a more strongly bound state. Biouptake of Cd in a freshwater oligochaete was reduced by 98% after 5-d contact of sediment with 4% Thiol-SAMMS and sorbed Cd was not bioavailable. While treatment with ATS reduced the small easily extractable portion of Pb in the sediment, the change in biouptake of Pb was not significant because most of the native lead was strongly bound. The selected sorbents added to sediments at a dose of 5% were mostly nontoxic to a range of sensitive freshwater and estuarine benthic organisms. Metal sorbent amendments in conjunction with activated carbon have the potential to simultaneously reduce metal and hydrophobic contaminant bioavailability in sediments. Environ. Toxicol. Chem. 2010;29:1883,1892. © 2010 SETAC [source] A spatially explicit, individual-based model to assess the role of estuarine nurseries in the early life history of North Sea herring, Clupea harengusFISHERIES OCEANOGRAPHY, Issue 1 2005JOACHIM MAES Abstract Herring (Clupea harengus) enter and remain within North Sea estuaries during well-defined periods of their early life history. The costs and benefits of the migrations between offshore spawning grounds and upper, low-salinity zones of estuarine nurseries are identified using a dynamic state-variable model, in which the fitness of an individual is maximized by selecting the most profitable habitat. Spatio-temporal gradients in temperature, turbidity, food availability and predation risk simulate the environment. We modeled predation as a function of temperature, the optical properties of the ambient water, the time allocation of feeding and the abundance of whiting (Merlangius merlangus). Growth and metabolic costs were assessed using a bioenergetic model. Model runs using real input data for the Scheldt estuary (Belgium, The Netherlands) and the southern North Sea show that estuarine residence results in fitter individuals through a considerable increase in survival probability of age-0 fish. Young herring pay for their migration into safer estuarine water by foregoing growth opportunities at sea. We suggest that temperature and, in particular, the time lag between estuarine and seawater temperatures, acts as a basic cue for herring to navigate in the heterogeneous space between the offshore spawning grounds at sea and the oligohaline nursery zone in estuaries. [source] Rare Earth Element Concentrations in the Natural Water Reference Materials (NRCC) NASS-5, CASS-4 and SLEW-3GEOSTANDARDS & GEOANALYTICAL RESEARCH, Issue 2 2007Michael G. Lawrence terres rares; yttrium; pré-concentration; ICP-MS; matériaux de référence du NRCC The rare earth element and yttrium concentrations of the NRCC reference materials North Atlantic Surface seawater, NASS-5; Coastal Atlantic Surface Seawater, CASS-4; and the estuarine water, SLEW-3 have been precisely determined by ICP-MS after ca. 1:8 preconcentration following a triple chelation using HDEHP (phosphoric acid 2-ethylhexyl ester -mono and di ester mixture) in heptane, and back extraction in nitric acid. We propose reference values with uncertainties for all naturally occurring lanthanides and yttrium. Les concentrations en terres rares et en yttrium des matériaux de référence suivants (du NRCC): l'eau de surface de l'Atlantique Nord NASS-5, l'eau de surface de l'Atlantique Côtier CASS-4 et l'eau d'estuaire SLEW-3 ont été déterminées précisément par ICP-MS après concentration d'un facteur 1 : 8 environ, suivie d'une triple chélation avec de l'HDEHP (mixture d'acide phosphorique 2-ethylhexyl ester - mono et di ester) dans de l'heptane et une extraction inverse en acide nitrique. Nous proposons des valeurs de référence avec leur incertitude pour toutes les terres rares naturelles et l'yttrium. [source] Spatial distribution and environmental correlates of Australian snubfin and Indo-Pacific humpback dolphinsECOGRAPHY, Issue 3 2006Guido J. Parra We present data on the spatial distribution of Australian snubfin and humpback dolphins using boat-based line transect surveys in three adjacent bays located in the Far Northern Section of the Great Barrier Reef Marine Park, northeast Queensland. We used Geographic Information Systems (GIS), and both randomization and Mantel tests to examine the relationship between the spatial distribution of the dolphins and three simple, readily quantified, environmental variables: distance to land, distance to river mouth, and water depth. Mantel tests allowed us to make clear inferences about the correlation of the species' distributions with environmental variables, while taking into account spatial autocorrelation and intercorrelation among variables. Randomization tests indicated snubfin and humpback dolphins occur closer to land than would be expected at random. Two-sample randomization tests indicated snubfin dolphins were found closer to river mouths than were humpback dolphins. Taking spatial autocorrelation into account, Mantel tests indicated all environmental variables were correlated with the spatial distribution of snubfin and humpback dolphins. Interspecific differences in spatial distribution appeared to be related to proximity to river mouths. Preference by snubfin and humpback dolphins for nearshore, estuarine waters is likely related to the productivity of these tropical coastal areas. This spatial analysis suggests that existing protected areas in this region may not include the most critical habitats for snubfin and humpback dolphins. The techniques used here shown relationships between the spatial distribution of the dolphins and environmental features that should facilitate their management and conservation. [source] The Ratios of Carbon, Nitrogen, and Phosphorus in a Wetland Coastal Ecosystem of Southern IndiaINTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 2 2003Lizen Mathews Abstract The fertility of the coastal and estuarine waters is of great concern because of its influence on the productivity of these waters. Seasonal variations in the distribution of organic carbon, total nitrogen and total phosphorus in the sediments of Kuttanad Waters, a part of the tropical Cochin Estuary on the south west coast of India, are examined to identify the contribution of sediments to the fertility of the aquatic systems. The adjoining region has considerable agricultural activity. The fresh water zones had higher quantities of silt and clay whereas the estuarine zone was more sandy. Organic carbon, total phosphorus and total nitrogen were higher in the fresh water zones and lower in the estuarine zones. Total phosphorus and organic carbon showed the lowest values during monsoon periods. No significant trends were observed in the seasonal distributions of total nitrogen. Ratios of C/N, C/P and N/P, and the phosphorus and nitrogen content indicate significant modification in the character of the organic matter. Substantial amounts of the organic matter can contribute to reducing conditions and modify diagenetic processes. [source] Prey selection by flounder, Platichthys flesus, in the Douro estuary, PortugalJOURNAL OF APPLIED ICHTHYOLOGY, Issue 3 2008C. Vinagre Summary Prey selection by the flounder, Platichthys flesus (Linnaeus, 1758), in an estuarine nursery was investigated and the major factors influencing food choice by this species were assessed. Diet breadth was narrow, reflecting the low prey diversity observed in the benthos. A gradual ontogenetic shift from small prey such as amphipods to larger prey like polychaetes and bivalves was observed. Amphipods had positive electivity values in the upper estuary and negative values in the lower estuary.Polychaetes showed the inverse pattern. Bivalve electivity values were always positive. Differential selectivity throughout the estuary was mainly related to spatial segregation of flounders according to size, with the smaller individuals concentrating in the upper estuary and larger individuals concentrating in the lower estuary. Amphipods such as Corophium spp. play a crucial role in the flounder diet because of their small size, low mobility and diel activity pattern. As prey, the polychaete value increases throughout flounder ontogeny since the flounder size range is compatible with the larger mouth gapes and detection ability of larger fish. Bivalve electivity values for flounder are mainly related to high calorific values. The absence of Crangon crangon (Linnaeus, 1758) in the diet may be due to low water temperature since the cost,benefit involved in the capture of highly mobile prey is too high at low temperatures. It was concluded that flounder must use several sensory features to detect and capture prey in turbid estuarine waters and that field studies provide important background information on the actual predator preferences under natural conditions. [source] RAPHIDOPHYCEAE [CHADEFAUD EX SILVA] SYSTEMATICS AND RAPID IDENTIFICATION: SEQUENCE ANALYSES AND REAL-TIME PCR ASSAYS,JOURNAL OF PHYCOLOGY, Issue 6 2006Holly A. Bowers Species within the class Raphidophyceae were associated with fish kill events in Japanese, European, Canadian, and U.S. coastal waters. Fish mortality was attributable to gill damage with exposure to reactive oxygen species (peroxide, superoxide, and hydroxide radicals), neurotoxins, physical clogging, and hemolytic substances. Morphological identification of these organisms in environmental water samples is difficult, particularly when fixatives are used. Because of this difficulty and the continued global emergence of these species in coastal estuarine waters, we initiated the development and validation of a suite of real-time polymerase chain reaction (PCR) assays. Sequencing was used to generate complete data sets for nuclear encoded small-subunit ribosomal RNA (SSU rRNA; 18S); internal transcribed spacers 1 and 2, 5.8S; and plastid encoded SSU rRNA (16S) for confirmed raphidophyte cultures from various geographic locations. Sequences for several Chattonella species (C. antiqua, C. marina, C. ovata, C. subsalsa, and C. verruculosa), Heterosigma akashiwo, and Fibrocapsa japonica were generated and used to design rapid and specific PCR assays for several species including C. verruculosa Hara et Chihara, C. subsalsa Biecheler, the complex comprised of C. marina Hara et Chihara, C. antiqua Ono and C. ovata, H. akashiwo Ono, and F. japonica Toriumi et Takano using appropriate loci. With this comprehensive data set, we were also able to perform phylogenetic analyses to determine the relationship between these species. [source] Photobleaching of Dissolved Organic Material from a Tidal Marsh-Estuarine System of the Chesapeake Bay,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2007Maria Tzortziou ABSTRACT Wetlands and tidal marshes in the Rhode River estuary of the Chesapeake Bay act as important sources of dissolved organic carbon and strongly absorbing dissolved organic matter (DOM) for adjacent estuarine waters. The effects of solar exposure on the photochemical degradation of colored DOM (CDOM) were examined for material derived from different sources (estuarine and freshwater parts of the Rhode River, sub-watershed stream, marshes) in this estuarine ecosystem. Consistent with changes in fluorescence emission, absorption loss upon exposure to different portions of the solar spectrum (i.e. different long-pass cut-off filters) occurred across the entire spectrum but the wavelength of maximum photobleaching decreased as the cut-off wavelength of the filter decreased. Our results illustrate that solar exposure can cause either an increase or a decrease in the CDOM absorption spectral slope, SCDOM, depending on the spectral quality of irradiation and, thus, on the parameters (e.g. atmospheric composition, concentration of UV-absorbing water constituents) that affect the spectral characteristics of the light to which CDOM is exposed. We derived a simple spectral model for describing the effects of solar exposure on CDOM optical quality. The model accurately, and consistently, predicted the observed dependence of CDOM photobleaching on the spectral quality of solar exposure. [source] Isolation and culture of the marine rotifer, Colurella dicentra (Gosse, 1887), from a Mississippi Gulf Coast estuaryAQUACULTURE RESEARCH, Issue 14 2006Paulinus Chigbu Abstract Few marine rotifer species (e.g. Encentrum linheii and Synchaeta cecilia) have been cultured successfully besides Brachionus plicatilis and B. rotundiformis, commonly used to rear larvae of many marine fish species. The development of culture techniques for marine rotifers smaller in size than the Brachionus species may be useful for rearing fish species for which the currently used prey are too large. We evaluated the possibility of culturing Colurella dicentra isolated from a Mississippi Gulf Coast estuary. An experiment was conducted to determine the effects of salinity (10,35 g L,1) on its population growth rate. Rotifers were fed Nannochloropsis oculata at a density of 100 000 cells mL,1 for 15 days. Colurella dicentra survived in water with a salinity of 10,47 g L,1. Densities of up to 300 rotifers mL,1 were sometimes attained in cultures. Salinity influenced C. dicentra production (P<0.001). The mean rotifer numbers at 10 g L,1 (22 840±2604 SD), 15 g L,1 (25 980±7071 SD) and 20 g L,1 (19 780±1029 SD) at the end of the experiment were similar (P>0.05), but were higher (P=0.05) than numbers at 25 g L,1 (4240±1783), 30 g L,1 (1300±264 SD) and 35 g L,1 (100±101 SD). The population growth rate (r) of the rotifers was the highest at 15 g L,1 (0.37,0.42 day,1), and the lowest at 35 g L,1 (,0.33,0.06 day,1). This is the first report of C. dicentra in the estuarine waters of the Gulf of Mexico, and also the first time it has been cultured successfully. [source] Low-Rank Smoothing Splines on Complicated DomainsBIOMETRICS, Issue 1 2007Haonan Wang Summary Smoothing over a domain with irregular boundaries or interior gaps and holes is addressed. Consider the problem of estimating mercury in sediment concentrations in the estuarine waters in New Hampshire. A modified version of low-rank thin plate splines (LTPS) is introduced where the geodesic distance is applied to evaluate dissimilarity of any two data observations: loosely speaking, distances between locations are not measured as the crow flies, but as the fish swims. The method is compared with competing smoothing techniques, LTPS, and finite element L-splines. [source] | |||||||||||||