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Ocean Waters (ocean + water)
Selected AbstractsMeasurement of pulmonary surfactant disaturated-phosphatidylcholine synthesis in human infants using deuterium incorporation from body waterJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 7 2005Paola E. Cogo Abstract The aim of the study was to determine surfactant palmitate disaturated-phosphatidylcholine (DSPC-PA) synthesis in vivo in humans by the incorporation of deuterium from total body water into DSPC-PA under steady state condition. We studied three newborns and one infant (body weight (BW) 4.6 ± 2.9 kg, gestational age 37.5 ± 2 weeks, age 9 ± 9 days) and four preterm newborns (BW 1.3 ± 0.6 kg, gestational age 30.3 ± 2.5 weeks, postnatal age 8.8 ± 9.2 h). All infants were mechanically ventilated during the study and the four preterm infants received exogenous surfactant at the start of the study. We administered 0.44 g 2H2O/kg BW as a bolus intravenously, followed by 0.0125 g 2H2O/kg BW every 6 h to maintain deuterium enrichment at plateau over 2 days. Urine samples and tracheal aspirates (TA) were obtained prior to dosing and every 6 h thereafter. Isotopic enrichment curves of DSPC-PA from sequential TA and urine deuterium enrichments were analyzed by Gas Chromatography-Isotope Ratio,Mass Spectrometry (GC-IRMS) and normalized for Vienna Standard Mean Ocean Water. Enrichment data were used to measure DSPC-PA fractional synthesis rate (FSR) from the linear portion of the DSPC-PA enrichment rise over time, relative to plateau enrichment of urine deuterium. Secretion time (ST) was defined as the time lag between the start of the study and the appearance of DSPC-PA deuterium enrichment in TA. Data were given as mean ± SD. All study infants reached deuterium-steady state in urine. DSPC-PA FSR was 6.5 ± 2.8%/day (range 2.6,10.2). FSR for infants who did not receive exogenous surfactant was 5.7 ± 3.5%/day (range 2.6,9.9%/day) and 7.3 ± 2.1%/day (range 5.1,10.2%/day) in the preterms, whereas DSPC-PA ST was 10 ± 10 h and 31 ± 10 h respectively. Surfactant DSPC-PA synthesis can be measured in humans by the incorporation of deuterium from body water. This study is a simpler and less invasive method compared to previously published methods on surfactant kinetics by means of stable isotopes. Copyright © 2005 John Wiley & Sons, Ltd. [source] Basin evolution, diagenesis and uranium mineralization in the Paleoproterozic Thelon Basin, Nunavut, CanadaBASIN RESEARCH, Issue 3 2010Eric E. Hiatt ABSTRACT The Paleoproterozoic (Statherian) Thelon Basin is located in the Churchill Province of the Canadian Shield, formed following the Trans-Hudson Orogeny. Basin formation followed an interval of felsic volcanism and weathering of underlying bedrock. The diagenetic evolution of the Thelon lasted about one billion years and was punctuated by fluid movement influenced by tectonic events. Early quartz cements formed in well-sorted, quartz-rich facies during diagenetic stage 1; fluids in which these overgrowths formed had ,18O values near 0, (Vienna Standard Mean Ocean Water). Uranium-rich apatite cement (P1) also formed during diagenetic stage 1 indicating that oxygenated, uranium-bearing pore water was present in the basin early in its diagenetic history. Syntaxial quartz cement (Q1) formed in water with ,18O from ,4 to ,0.8, in diagenetic stage 2. Diagenetic stage 3 occurred when the Thelon Formation was at ca. 5 km depth, and was marked by extensive illitization, alteration of detrital grains, and uranium mineralization. Basin-wide, illite crystallized at ,200 °C by fluids with ,18O values of 5,9, and ,D values of ,60 to ,31,, consistent with evolved basinal brines. Tectonism caused by the accretion of Nena at ca. 1600 Ma may have provided the mechanism for brine movement during deep burial. Diagenetic stage 4 is associated with fracturing and emplacement of mafic dikes at ca. 1300 Ma, quartz cement (Q3) in fractures and vugs, further illitization, and recrystallization of uraninite (U2). Q3 cements have fluid inclusions that suggest variable salinities, ,18O values of 1.5,9,, and ,D values of ,97 to ,83, for stage 4 brines. K-feldspar and Mg-chlorite formed during diagenetic stage 5 at ca. 1000 Ma in upper stratigraphic sequences, and in the west. These phases precipitated from low-temperature, isotopically distinct fluids. Their distribution indicates that the basin hydrostratigraphy remained partitioned for >600 Ma. [source] Diversity and distribution of pigmented heterotrophic bacteria in marine environmentsFEMS MICROBIOLOGY ECOLOGY, Issue 1 2006Hailian Du Abstract A systematic investigation of marine pigmented heterotrophic bacteria (PHB) based on the cultivation method and sequencing analysis of 16S rRNA genes was conducted in Chinese coastal and shelf waters and the Pacific Ocean. Both the abundance of PHB and the ratio of PHB to CFU decreased along trophic gradients from coastal to oceanic waters, with the highest values of 9.9 × 103 cell mL,1 and 39.6%, respectively, in the Yangtze River Estuary. In contrast to the total heterotrophic bacteria (TB) and CFU, which were present in the whole water column, PHB were primarily confined to the euphotic zone, with the highest abundance of PHB and ratio of PHB to CFU occurring in surface water. In total, 247 pigmented isolates were obtained during this study, and the phylogenetic analysis showed a wide genetic diversity covering 25 genera of six phylogenetic classes: Alphaproteobacteria, Gammaproteobacteria, Actinobacteria, Bacilli, Flavobacteria and Sphingobacteria. PHB belonging to Alphaproteobacteria, Flavobacteria and Sphingobacteria were obtained mainly from the South China Sea and East China Sea; PHB from the Pacific Ocean water were predominantly affiliated with Gammaproteobacteria, and most isolates from the Yangtze River Estuary fell into the classes Actinobacteria and Bacilli. The isolates exhibited various colours (e.g. golden, yellow, red, pink and orange), with genus or species specificity. Furthermore, the pigment of PHB cells absorbed light mainly in the wavelength range between 450 and 550 nm. In conclusion, our work has revealed that PHB with broad genetic diversity are widely distributed in the marine environment, and may account for up to 39.6% of culturable bacteria, equivalent to 1.4% of the total microbial community. This value might even be underestimated because it is probable that not all pigmented bacteria were isolated. Their abundance and genetic distribution are heavily influenced by environmental properties, such as light and nutrition, suggesting that they have important roles in the marine ecosystem, especially in the absorption of visible light. [source] Synopsis of biological, fisheries and aquaculture-related information on mulloway Argyrosomus japonicus (Pisces: Sciaenidae), with particular reference to AustraliaJOURNAL OF APPLIED ICHTHYOLOGY, Issue 1 2008V. Silberschneider Summary Argyrosomus japonicus is a member of the family Sciaenidae, which are commonly known as drums and croakers. A. japonicus occurs in estuarine and nearshore Pacific Ocean and Indian Ocean waters surrounding Australia, Africa, India, Pakistan, China, Korea and Japan. The biology of A. japonicus is relatively well studied in South Africa, and more recently studied in Australia, but no information is readily available from other areas of its distributional range. The early life history distribution of A. japonicus may differ among regions, with their distribution in estuaries linked to salinity, turbidity, freshwater flows and depth of water. Studies in South Africa and Australia found that juvenile fish grow rapidly, attaining 35 cm TL in 1 year and 87,90 cm TL in 5 years. Sexual maturity also differs among regions and is attained at 2,3 years of age and >50 cm in eastern Australia, 5,6 years of age and >80 cm TL in western Australia and southern Africa. The maximum reported length and age of A. japonicus is 175 cm and 42 years, respectively. Spawning most likely occurs in nearshore coastal waters although there is evidence to suggest that it may also occur in the lower reaches of estuaries. Time of spawning varies among geographic localities and is probably linked to water temperature and oceanography. Juvenile fish (<2 years) appear to be relatively sedentary, but sub-adults and adults can move relatively long distances (>200 km) and such movements may be linked to pre-spawning migrations. A. japonicus is important in many recreational and commercial fisheries, but like other sciaenids, is prone to overfishing. It is classified as recruitment overfished in South Africa and overfished in eastern Australia. Although much research has been done to minimize the capture of juveniles in Australian prawn-trawl fisheries, greater protection of spawners and improved fishing practices to enhance survival of discarded juveniles, particularly from prawn trawling, may be required. An aquaculture industry is developing for A. japonicus in Australia and preliminary research on the impacts and success of re-stocking wild populations has begun in an attempt to arrest the apparent decline in populations. [source] Does saltwater flushing reduce viability of diapausing eggs in ship ballast sediment?DIVERSITY AND DISTRIBUTIONS, Issue 3 2006Sarah A. Bailey ABSTRACT Flushing of ballast tanks with seawater has been proposed to reduce the risk of invasion associated with residual ballast in ,no ballast on board' ships. The efficacy of this procedure, however, has not been determined. Using diapausing eggs isolated from ballast sediments , as well as from Lake Erie sediment , this study investigated the impact of salinity (0, 8 and 35,) and temperature (10, 20 and 30 °C) on the cumulative abundance and species richness of hatched zooplankton taxa. The rate and amount of hatching varied dramatically between sediments and across salinity,temperature regimes. Although exposure to saline water inhibited emergence of freshwater taxa during the exposure phase of all trials, mixed results were evident after diapausing eggs were returned to freshwater. The efficacy of salinity as a ballast treatment method was temperature dependent, although the direction of the effect was case-specific. Exposure of eggs to saline water was less effective at 10 and 30 °C than at 20 °C. Although flushing ballast tanks with open ocean water is expected to significantly reduce the number of active invertebrates living in residual ballast water (a potentially larger source of invaders), our results indicate that the most effective treatment conditions for reduction of diapausing egg viability is 8, salinity at 20 °C. [source] Niches of the pre-photosynthetic biosphere and geologic preservation of Earth's earliest ecologyGEOBIOLOGY, Issue 2 2007NORMAN H. SLEEP ABSTRACT The tree of terrestrial life probably roots in non-photosynthetic microbes. Chemoautotrophs were the first primary producers, and the globally dominant niches in terms of primary productivity were determined by availability of carbon dioxide and hydrogen for methanogenesis and sulfite reduction. Methanogen niches were most abundant where CO2 -rich ocean water flowed through serpentinite. Black smoker vents from basalt supplied comparable amount of H2. Hydrogen from arc volcanoes supported a significant methanogenic niche at the Earth's surface. SO2 from arc volcanoes reacted with organic matter and hydrogen, providing a significant surface niche. Methane ascended to the upper atmosphere where photolysis produced C-rich haze and CO, and H escaped into space. The CO and C-rich haze supported secondary surface niches. None of these ecologies were bountiful; less than 1% of the CO2 vented by ridge axes, arcs, and metamorphism became organic matter before it was buried in carbonate. In contrast, a photosynthetic biosphere leaves copious amounts of organic carbon, locally concentrated in sediments. Black shales are a classic geologic biosignature for photosynthesis that can survive subduction and high-grade metamorphism. [source] Estimation of mean residence times of subsurface waters using seasonal variation in deuterium excess in a small headwater catchment in JapanHYDROLOGICAL PROCESSES, Issue 3 2007Naoki Kabeya Abstract We measured deuterium excess (d = ,D , 8,18O) in throughfall, groundwater, soil water, spring water, and stream water for 3 years in a small headwater catchment (Matsuzawa, 0·68 ha) in the Kiryu Experimental Watershed in Japan. The d value represents a kinetic effect produced when water evaporates. The d value of the throughfall showed a sinusoidal change (amplitude: 6·9, relative to Vienna standard mean ocean water (V-SMOW)) derived from seasonal changes in the source of water vapour. The amplitude of this sinusoidal change was attenuated to 1·3,6·9, V-SMOW in soil water, groundwater, spring water, and stream water. It is thought that these attenuations derive from hydrodynamic transport processes in the subsurface and mixing processes at an outflow point (stream or spring) or a well. The mean residence time (MRT) of water was estimated from d value variations using an exponential-piston flow model and a dispersion model. MRTs for soil water were 0,5 months and were not necessarily proportional to the depth. This may imply the existence of bypass flow in the soil. Groundwater in the hillslope zone had short residence times, similar to those of the soil water. For groundwater in the saturated zone near the spring outflow point, the MRTs differed between shallow and deeper groundwater; shallow groundwater had a shorter residence time (5,8 months) than deeper groundwater (more than 9 months). The MRT of stream water (8,9 months) was between that of shallow groundwater near the spring and deeper groundwater near the spring. The seasonal variation in the d value of precipitation arises from changes in isotopic water vapour composition associated with seasonal activity of the Asian monsoon mechanism. The d value is probably an effective tracer for estimating the MRT of subsurface water not only in Japan, but also in other East Asian countries influenced by the Asian monsoon. Copyright © 2006 John Wiley & Sons, Ltd. [source] The effects of water source and secondary water treatment on flame angelfish Centropyge loriculus (Günther) reproductionAQUACULTURE RESEARCH, Issue 10 2010Chatham K Callan Abstract This study was conducted to determine whether water source and water treatment affected flame angelfish (Centropyge loriculus) reproduction. Flame angelfish broodstock were maintained and monitored for reproductive performance (fecundity, egg fertilization rates and egg viability) in either untreated well-water (WW), sterilized ocean water (OW) or WW treated by intensive recirculation treatment (biological filtration, protein skimming, UV sterilization and mechanical filtration) (RAS). Results of this experiment indicated that although pairs maintained in WW initially exhibited good spawning performance, fecundity, egg fertilization rates and egg viability declined after 25 weeks. Treatment of WW by recirculation did not significantly improve flame angelfish reproductive performance with only moderately improved fecundity compared with pairs in the WW treatment. In contrast, pairs held in sterilized OW exhibited significantly greater fecundity, egg fertilization rates and egg viability from week 25 onwards than pairs in either the WW or RAS treatments. However, in the process of developing OW biosecurity protocols, we found that sterilization of OW using chlorine at levels >25 mg L,1 (30 min) negatively affected flame angelfish egg fertilization rates indicating that alternative methods of water sterilization may be warranted. [source] Abundances of crenarchaeal amoA genes and transcripts in the Pacific OceanENVIRONMENTAL MICROBIOLOGY, Issue 3 2010Matthew J. Church Summary Planktonic Crenarchaea are thought to play a key role in chemolithotrophic ammonia oxidation, a critical step of the marine nitrogen (N) cycle. In this study, we examined the spatial distributions of ammonia-oxidizing Crenarchaea across a large (,5200 km) region of the central Pacific Ocean. Examination of crenarchaeal 16S rRNA, ammonia monooxygenase subunit A (amoA) genes, and amoA transcript abundances provided insight into their spatial distributions and activities. Crenarchaeal gene abundances increased three to four orders of magnitude with depth between the upper ocean waters and dimly lit waters of the mesopelagic zone. The resulting median value of the crenarchaeal amoA: 16S rRNA gene ratio was 1.3, suggesting the majority of Crenarchaea in the epi- and mesopelagic regions of the Pacific Ocean have the metabolic machinery for ammonia oxidation. Crenarchaeal amoA transcript abundances typically increased one to two orders of magnitude in the transitional zone separating the epipelagic waters from the mesopelagic (100,200 m), before decreasing into the interior of the mesopelagic zone. The resulting gene copy normalized transcript abundances revealed elevated amoA expression in the upper ocean waters (0,100 m) where crenarchaeal abundances were low, with transcripts decreasing into the mesopelagic zone as crenarchaeal gene abundances increased. These results suggest ammonia-oxidizing Crenarchaea are active contributors to the N cycle throughout the epi- and mesopelagic waters of the Pacific Ocean. [source] The potential significance of microbial Fe(III) reduction during deposition of Precambrian banded iron formationsGEOBIOLOGY, Issue 3 2005K. O. KONHAUSER ABSTRACT During deposition of late Archean,early Palaeoproterozoic Precambrian banded iron formations (BIFs) the downward flux of ferric hydroxide (Fe(OH)3) and phytoplankton biomass should have facilitated microbial Fe(III) reduction. However, quantifying the significance of such a metabolic pathway in the Precambrian is extremely difficult, considering the post-depositional alteration of the rocks and the lack of ideal modern analogues. Consequently, we have very few constraints on the Fe cycle at that time, namely (i) the concentration of dissolved Fe(II) in the ocean waters; (ii) by what mechanisms Fe(II) was oxidized (chemical, photochemical or biological, the latter using either O2 or light); (iii) where the ferric hydroxide was precipitated (over the shelf vs. open ocean); (iv) the amount of phytoplankton biomass, which relates to the nutrient status of the surface waters; (v) the relative importance of Fe(III) reduction vs. the other types of metabolic pathways utilized by sea floor microbial communities; and (vi) the proportion of primary vs. diagenetic Fe(II) in BIF. Furthermore, although estimates can be made regarding the quantity of reducing equivalents necessary to account for the diagenetic Fe(II) component in Fe-rich BIF layers, those same estimates do not offer any insights into the magnitude of Fe(III) actually generated within the water column, and hence, the efficiency of Fe and C recycling prior to burial. Accordingly, in this study, we have attempted to model the ancient Fe cycle, based simply on conservative experimental rates of photosynthetic Fe(II) oxidation in the euphotic zone. We estimate here that under ideal growth conditions, as much as 70% of the biologically formed Fe(III) could have been recycled back into the water column via fermentation and organic carbon oxidation coupled to microbial Fe(III) reduction. By comparing the potential amount of biomass generated phototrophically with the reducing equivalents required for Fe(III) reduction and magnetite formation, we also hypothesize that another anaerobic metabolic pathway might have been utilized in the surface sediment to oxidize the fermentation by-products. Based on the premise that the deep ocean waters were anoxic, this role could have been fulfilled by methanogens, and maybe even methanotrophs that employed Fe(III) reduction. [source] Reproductive biology of two co-occurring mugilids, Liza argentea and Myxus elongatus, in south-eastern AustraliaJOURNAL OF FISH BIOLOGY, Issue 4 2008B. W. Kendall The reproductive biology of Liza argentea and Myxus elongatus occurring in two estuaries (Lake Macquarie and St Georges Basin) was found to differ. Gonado-somatic index values and macroscopic staging of gonads identified the peak spawning period of L. argentea occurred between March and November in Lake Macquarie and January and April in St Georges Basin. In contrast, peak spawning of M. elongatus was concentrated between January and March in both estuaries. Spawning of L. argentea probably occurred in the lower reaches of estuaries as well as in nearshore coastal waters, whereas evidence indicated M. elongatus spawned only in ocean waters. The mean fork length at maturity (LF50) was greater for females than males in both species, and it also occurred at a larger mean LF in M. elongatus (males = 230 mm and females = 255 mm) than L. argentea (males = 180 mm and females = 207 mm). Estimates of total potential fecundity were also greater for M. elongatus (425 484,1 157 029) compared to L. argentea (159 933,548 954). Both species had determinate fecundity and displayed a group synchronous pattern of oocyte development, with two distinct size classes of oocytes present in mature ovaries. Liza argentea probably release the larger class of oocytes in one spawning event, but this could not be established for M. elongatus. [source] GLOBAL SYSTEMATIC AND PHYLOGENETIC ANALYSIS OF SARGASSUM IN THE GULF OF MEXICO, CARIBBEAN AND PACIFIC BASINJOURNAL OF PHYCOLOGY, Issue 2000N. Phillips Sargassum is one of the most species-rich genera in the brown algae with over 400 described species worldwide. The bulk of these species occurs in Pacific-Indian ocean waters with only a small portion found on the Atlantic side of the Isthmus of Panama. Sargassum also has one of the most subdivided and complex taxonomic systems used within the algae. Systematic distinctions within the genus are further complicated by high rates of phenotypic variability in several key morphological characters. Molecular analyses in such systems should allow testing of systematic concepts while providing insights into speciation and evolutionary patterns. Global molecular phylogenetic analyses using both conserved and variable regions of the Rubisco operon (rbcL and rbcL-IGS-rbcS) were performed with species from the Gulf of Mexico, Caribbean, and Pacific basin. Results confirm earlier analyses based on rbcL-IGS- rbcS from Pacific species at the subgeneric and sectional level while providing additional insights into the systematics and phylogenetics on a global scale. For example, species east of the Isthmus of Panama form a distinct well-resolved clade within the tropical subgenus. This result in sharp contrast to traditional systematic treatments but provides a window into the evolutionary history of this genus in the Pacific and Atlantic Ocean basins and a possible means to time speciation events. [source] Isolation and characterization of microsatellite loci in the icefish Chionodraco rastrospinosus (Perciformes, Notothenioidea, Channichthyidae)MOLECULAR ECOLOGY RESOURCES, Issue 1 2006CHIARA PAPETTI Abstract We characterized eight polymorphic microsatellites in the icefish Chionodraco rastrospinosus (Perciformes, Notothenioidea, Channichthyidae). Microsatellites were isolated from a partial genomic library enriched for an AC motif. Chionodraco rastrospinosus is an endemic species inhabiting southern ocean waters surrounding the Antarctic Peninsula, the South Shetland Islands, and the South Orkney Islands. An excess of homozygotes was observed in seven out of the eight investigated loci; however, presence of null alleles was detected only for three of them suggesting that other factors may act in reducing heterozygosity. These molecular markers will be useful to investigate icefish genetic structure, possibly providing insights on its effective population size and demographic history. [source] | |||||||||||||