Report on the physical, bacteriological and biochemical analyses of seawater samples collected off existing sewage outfalls in the Sierra Leone River Estuary

The studies reported were undertaken as part of a wide environmental feasibility study for the establishment of a modern sewage system in Freetown. The aim of this part of the study was to determine whether the hydrological regime of the Sierra Leone River Estuary would permit the large-scale introduction of sewage into the estuary without damaging the environment. The important factors were whether: 1) there would be sufficient dilution of the sewage; 2) fleatable particles or other substances would create significant adverse effects in the estuarine ecosystem. The outfall sites are described together with the sampling stations, methods and analyses. Results include: 1) T/S profiles; 2) chemical analysis of the water. A review of literature on the Sierra Leone River Estuary is included which provides information on the plankton, benthos and fisheries. Results suggest that at certain points where local circulations occur it would be inadvisable to locate untreated sewage outfalls. Such points are frequently observed in small embayments. These studies have been of short duration but the data can serve as baseline for more extended investigations which would give a more complete picture of the seasonal patterns in the estuary.

Seawater irrigation systems for intensive marine shrimp farming in Thailand

The aim of the seawater irrigation system (SIS) is to clean up shrimp pond effluent and provide high quality seawater for shrimp farming. The system has 3 components: water intake; treatment reservoir and discharge system. There are criteria for site selection because shrimp farmers are required to form associations so they can work closely together. The construction site must be on the coastal area outside a mangrove forest and located away from a production agricultural area. All construction sites must have undergone an environmental impact assessment, and should be located on the area listed in Thailand's Coastal Zone Management Plan. Five SIS projects, which cover a culture area of 6,500 ha with 1,300 farmers (families), were completed and operated. The Department of Fisheries has planned for another 28 projects, that will cover almost 44,000 ha of culture area.

Methane hydrate growth velocity in seepage system of Qiongdongnan Basin, South China Sea

The occurrences of diapirs, gas-filled zones and gas plumes in seawater in Qiongdongnan Basin of South China Sea indicate that there may exist seepage system gas-hydrate reservoirs. Assuming there has a methane venting zone of 1500 m in diameter, and the methane flux is 1000 kmol/a, and the temperature of methane hydrate-bearing sediments ranges from 3 degrees C to 20 degrees C, then according to the hydrate film growth theory, by numerical simulation, this paper computes the temperatures and velocities in 0 mbsf, 100 mbsf, 200 mbsf, 425 mbsf over discrete length, and gives the change charts. The results show that the cementation velocity in sediments matrix of methane hydrate is about 0.2 nm/s, and the seepage system will evolve into diffusion system over probably 35000 years. Meanwhile, the methane hydrate growth velocity in leakage system is 20 similar to 40 times faster than in diffusion system.

Experimental study on the fractionation of yttrium from holmium during the coprecipitation with calcium carbonates in seawater solutions

The partitioning of Y and Ho between CaCO3 (calcite and aragonite respectively) and seawater was experimentally investigated at 25 degrees C and I atm. Both Y and Ho were observed to be strongly partitioned into the overgrowths of calcite or aragonite. Their partition coefficients, D-Y and D-Ho, were determined to be similar to 520-1400 and similar to 700-1900 in calcite, similar to 1200-2400 and similar to 2400-4300 in aragonite, respectively. Y fractionates from Ho during the coprecipitation with either calcite or aragonite. Within our experimental conditions, the fractionation factor, k = D-Y/D-Ho, was determined to be similar to 0.62-0.77 in calcite and similar to 0.50-0.57 in aragonite, respectively. The aqueous complexation of Y and Ho, which is a function of solution chemistry, probably plays an important role in both the partitioning and the fractionation. Further analyses suggest that the difference in covalency between Y and Ho associated with changes in their coordination environments is the determinant factor to the Y-Ho fractionation in the H2CO3-CaCO3 System.

Tide-influenced acidic hydrothermal system offshore NE Taiwan

Elemental sulfur and hydrogen sulfide emitted offshore of northeastern Taiwan known to local fishermen for generations, but never studied until recently, are found to have originated from a cluster of shallow (< 30 m depth) hydrothermal vents. Among the mounds is a massive 6 m high chimney with a diameter of 4 m at the base composed of almost pure sulfur and discharging hydrothermal fluid containing sulfur particles. The sulfur in the chimney has a delta(34)S= 1.1 parts per thousand that is isotopically lighter than seawater. A yellow smoker at shallow depths with such characteristics has never been reported on anywhere else in the world. Gas discharges from these vents are dominated by CO2 (> 92%) with small amounts of H2S. Helium isotopic ratios 7.5 times that of air indicate that these gases originate from the mantle. High temperature hydrothermal fluids have measured temperatures of 78-116 degrees C and pH (25 degrees C) values as low as 1.52, likely the lowest to be found in world records. Low temperature vents (30-65 degrees C) have higher pH values. Continuous temperature records from one vent show a close correlation with diumal tides, suggesting rapid circulation of the hydrothermal fluids. (c) 2005 Elsevier B.V. All rights reserved.

Determination of multiple trace elements in seawater using chelation ion chromatography and ICP-MS

An off-line chelation system combined with ICP-MS technique was developed for the quantitative determination of trace elements in seawater, namely V, Co, Ni, Cu, Zn, Mo, Cd, Pb, U and rare earth elements(REEs). The system was built based on an ion chromatography equipped with MetPac((R)) CC-I chelation columns which had a strong selective chelation to these target elements within a pH range 5.2-5.6. Acidified seawater samples and NH4Ac(2 mol/L) were blended to meet suitable pH before being injected into the chelation column, thus target elements were retained while alkali and alkaline metals were excluded. Then chelated elements were eluted by HNO3 (1 mol/L) and samples were collected for ICP-MS analysis. Varying the ratio of input( gen. 200 mL) to output( gen. 5 mL), the target elements which were concentrated as 40 times as their concentrations were far beyond instrumental quantification limits. At last, a certificated seawater CASS-4 was introduced and our detected values were in good agreement with those certified values.

Seasonal dynamics of the carbonate system in the Western English Channel

We present over 900 carbonate system observations collected over four years (2007–2010) in the Western English Channel (WEC). We determined CO2 partial pressure (pCO2), Total Alkalinity (TA) and Dissolved Inorganic Carbon (DIC) along a series of 40 km transects, including two oceanographic stations (L4 and E1) within a sustained coastal observatory. Our data follow a seasonal pattern of CO2 undersaturation from January to August, followed by supersaturation in September–October and a return to near-equilibrium thereafter. This pattern is explained by the interplay of thermal and biological sinks in winter and spring–summer, respectively, followed by the breakdown of stratification and mixing with deeper, high-CO2 water in autumn. The drawdown of DIC and inorganic N between March and June with a C:N ratio of 8.7–9.5 was consistent with carbon over-consumption during phytoplankton growth. Monthly mean surface pCO2 was strongly correlated with depth integrated chlorophyll a highlighting the importance of subsurface chlorophyll a maxima in controlling C-fluxes in shelf seas. Mixing of seawater with riverine freshwater in near-shore samples caused a reduction in TA and the saturation state of calcite minerals, particularly in winter. Our data show that the L4 and E1 oceanographic stations were small, net sinks for atmospheric CO2 over an annual cycle (−0.52±0.66 mol C m−2 y−1 and −0.62±0.49 mol C m−2 y−1, respectively).

The carbonate system of the NW European shelf: sensitivity and model validation

The ocean plays an important role in regulating the climate, acting as a sink for carbon dioxide, perturbing the carbonate system and resulting in a slow decrease of seawater pH. Understanding the dynamics of the carbonate system in shelf sea regions is necessary to evaluate the impact of Ocean Acidification (OA) in these societally important ecosystems. Complex hydrodynamic and ecosystem coupled models provide a method of capturing the significant heterogeneity of these areas. However rigorous validation is essential to properly assess the reliability of such models. The coupled model POLCOMS–ERSEM has been implemented in the North Western European shelf with a new parameterization for alkalinity explicitly accounting for riverine inputs and the influence of biological processes. The model has been validated in a like with like comparison with North Sea data from the CANOBA dataset. The model shows good to reasonable agreement for the principal variables, physical (temperature and salinity), biogeochemical (nutrients) and carbonate system (dissolved inorganic carbon and total alkalinity), but simulation of the derived variables, pH and pCO2, are not yet fully satisfactory. This high uncertainty is attributed mostly to riverine forcing and primary production. This study suggests that the model is a useful tool to provide information on Ocean Acidification scenarios, but uncertainty on pH and pCO2 needs to be reduced, particularly when impacts of OA on ecosystem functions are included in the model systems.

Development and validation of a shipboard system for measuring high-resolution vertical profiles of aqueous dimethylsulfide concentrations using chemical ionization mass spectrometry

A sampling and analytical system has been developed for shipboard measurements of high-resolution vertical profiles of the marine trace gas dimethylsulfide (DMS). The system consists of a tube attached to a CTD with a peristaltic pump on deck that delivers seawater to a membrane equilibrator and atmospheric pressure chemical ionization mass spectrometer (Eq-APCIMS). This allows profiling DMS concentrations to a depth of 50 m, with a depth resolution of 1.3-2 m and a detection limit of nearly 0.1 nmol L-1. The seawater is also plumbed to allow parallel operation of additional continuous instruments, and simultaneous collection of discrete samples for complementary analyses. A valve alternates delivery of seawater from the vertical profiler and the ship�s underway intake, thereby providing high-resolution measurements in both the vertical and horizontal dimensions. Tests conducted on various cruises in the Mediterranean Sea, Atlantic, Indian, and Pacific Oceans show good agreement between the Eq-APCIMS measurements and purge and trap gas chromatography with flame photometric detection (GC-FPD) and demonstrate that the delivery of seawater from the underway pump did not significantly affect endogenous DMS concentrations. Combination of the continuous flow DMS analysis with high-frequency hydrographic, optical, biological and meteorological measurements will greatly improve the spatial/temporal resolution of seagoing measurements and improve our understanding of DMS cycling.

Microbial community of the deep-sea brine Lake Kryos seawater-brine interface is active below the chaotropicity limit of life as revealed by recovery of mRNA

Within the complex of deep, hypersaline anoxic lakes (DHALs) of the Mediterranean Ridge, we identified a new, unexplored DHAL and named it ‘Lake Kryos’ after a nearby depression. This lake is filled with magnesium chloride (MgCl2)-rich, athalassohaline brine (salinity > 470 practical salinity units), presumably formed by the dissolution of Messinian bischofite. Compared with the DHAL Discovery, it contains elevated concentrations of kosmotropic sodium and sulfate ions, which are capable of reducing the net chaotropicily of MgCl2-rich solutions. The brine of Lake Kryos may therefore be biologically permissive at MgCl2 concentrations previously considered incompatible with life. We characterized the microbiology of the seawater–Kryos brine interface and managed to recover mRNA from the 2.27–3.03 MMgCl2 layer (equivalent to 0.747–0.631 water activity), thereby expanding the established chaotropicity window-for-life. The primary bacterial taxa present there were Kebrit Deep Bacteria 1 candidate division and DHAL-specific group of organisms, distantly related toDesulfohalobium. Two euryarchaeal candidate divisions, Mediterranean Sea Brine Lakes group 1 and halophilic cluster 1, accounted for > 85% of the rRNA-containing archaeal clones derived from the 2.27–3.03 M MgCl2 layer, but were minority community-members in the overlying interface-layers. These findings shed light on the plausibility of life in highly chaotropic environments, geochemical windows for microbial extremophiles, and have implications for habitability elsewhere in the Solar System.

Development of Bioreactors for Nitrifying Water In Closed System Hatcheries Of Penaeid And Non-Penaeid Prawns

In the present study the development of bioreactors for nitrifying water in closed system hatcheries of penaeid and non-penaeid prawns. This work is an attempt in this direction to cater to the needs of aquaculture industry for treatment and remediation of ammonia and nitrate in penaeid and non-penaeid hatcheries, by developing nitrifying bacteria allochthonous to the particular environment under consideration, and immobilizing them on an appropriately designed support materials configured as reactors. Ammonia toxicity is the major limiting factors in penaeid and non-penaeid hatchery systems causing lethal and sublethal effects on larvae depending on the pH values. Pressing need of the aquaculture industry to have a user friendly and economically viable technology for the removal of ammonia, which can be easily integrated to the existing hatchery designs without any major changes or modifications. Only option available now is to have biological filters through which water can be circulated for the oxidation of ammonia to nitrate through nitrite by a group of chemolithotrophs known as nitrifying bacteria. Two types of bioreactors have been designed and developed. The first category named as in situ stringed bed suspended bioreactor(SBSBR) was designed for use in the larval rearing tanks to remove ammonia and nitrite during larval rearing on a continuous basis, and the other to be used for nitrifying freshly collected seawater and spent water named as ex situ packed bed bioreactior(PBBR). On employing the two reactors together , both penaeid and non-penaeid larval rearing systems can be made a closed recirculating system at least for a season. A survey of literature revealed that the in situ stringed bed suspended reactor developed here is unique in its design, fabrication and mode of application.

Chitosan as a wall material for a microencapsulated delivery system for Macrobrachium rosenbergii(de Man) larvae

Chitosan has beenwidely accepted as awall material for preparing microcapsules of various purposes in human medicine. The possibility of using chitosan as a wall material for microencapsulating nutrients and drugs for aquaculture purposes, speci¢cally to Macrobrachium rosenbergii larvae was evaluated in this study. Two types of chitosan-coated microcapsules were prepared using either acetone (MEC-A) or NaOH (MEC-N) as the cross-linking agents. They were compared with a microbound diet relative to total leaching of nutrients and free amino acids (FAA). Among the microcapsules, MEC-N showed the lowest level of total leaching of nutrients (23.3%) during 5 h of immersion in seawater and released 65% FAA after 60min. During laboratory trials,75% larvae had accepted the MEC-N capsule. The results of the study suggest that chitosan can be used as a wall material for preparing microcapsules to deliver drugs and nutrients to M. rosenbergii larvae.

A novel medium for the development of in vitro cell culture system from Penaeus monodon

Lack of a valid shrimp cell line has been hampering the progress of research on shrimp viruses. One of the reasons identified was the absence of an appropriate medium which would satisfy the requirements of the cells in vitro. We report the first attempt to formulate an exclusive shrimp cell culture medium (SCCM) based on the haemolymph components of Penaeus monodon prepared in isosmotic seawater having 27 % salinity. The SCCM is composed of 22 amino acids, 4 sugars, 6 vitamins, cholesterol, FBS, phenol red, three antibiotics, potassium dihydrogen phosphate and di-sodium hydrogen phosphate at pH 6.8–7.2. Osmolality was adjusted to 720 ± 10 mOsm kg-1 and temperature of incubation was 25 8C. The most appropriate composition was finally selected based on the extent of attachment of cells and their proliferation by visual observation. Metabolic activity of cultured cells was measured by MTT assay and compared with that in L-15 (29), modified L-15 and Grace’s insect medium, and found better performance in SCCM especially for lymphoid cells with 107 % increase in activity and 85 ± 9 days of longevity. The cells from ovary and lymphoid organs were passaged twice using the newly designed shrimp cell dissociation ‘‘cocktail’’.

Kinetic study of the plastoquinone pool availability correlated with H2O2 release in seawater and antioxidant responses in the red alga Kappaphycus alvarezii exposed to single or combined high light, chilling and chemical stresses

Under biotic/abiotic stresses, the red alga Kappaphycus alvarezii reportedly releases massive amounts of H2O2 into the surrounding seawater. As an essential redox signal, the role of chloroplast-originated H2O2 in the orchestration of overall antioxidant responses in algal species has thus been questioned. This work purported to study the kinetic decay profiles of the redox-sensitive plastoquinone pool correlated to H2O2 release in seawater, parameters of oxidative lesions and antioxidant enzyme activities in the red alga Kappaphycus alvarezii under the single or combined effects of high light, low temperature, and sub-lethal doses of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) and 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIB), which are inhibitors of the thylakoid electron transport system. Within 24 h, high light and chilling stresses distinctly affected the availability of the PQ pool for photosynthesis, following Gaussian and exponential kinetic profiles, respectively, whereas combined stimuli were mostly reflected in exponential decays. No significant correlation was found in a comparison of the PQ pool levels after 24 h with either catalase (CAT) or ascorbate peroxidase (APX) activities, although the H2O2 concentration in seawater (R = 0.673), total superoxide dismutase activity (R = 0.689), and particularly indexes of protein (R = 0.869) and lipid oxidation (R = 0.864), were moderately correlated. These data suggest that the release of H2O2 from plastids into seawater possibly impaired efficient and immediate responses of pivotal H2O2-scavenging activities of CAT and APX in the red alga K. alvarezii, culminating in short-term exacerbated levels of protein and lipid oxidation. These facts provided a molecular basis for the recognized limited resistance of the red alga K. alvarezii under unfavorable conditions, especially under chilling stress. © 2006 Elsevier B.V. All rights reserved.

Temporal dynamics of benthic assemblages along a gradient of ocean acidification at a CO2 vent’s system of the Ischia Island

Global warming and ocean acidification, due to rising atmospheric levels of CO2, represent an actual threat to terrestrial and marine environments. Since Industrial Revolution, in less of 250 years, pH of surface seawater decreased on average of 0.1 unit, and is expected to further decreases of approximately 0.3-0.4 units by the end of this century. Naturally acidified marine areas, such as CO2 vent systems at the Ischia Island, allow to study acclimatation and adaptation of individual species as well as the structure of communities, and ecosystems to OA. The main aim of this thesis was to study how hard bottom sublittoral benthic assemblages changed trough time along a pH gradient. For this purpose, the temporal dynamics of mature assemblages established on artificial substrates (volcanic tiles) over a 3 year- period were analysed. Our results revealed how composition and dynamics of the community were altered and highly simplified at different level of seawater acidification. In fact, extreme low values of pH (approximately 6.9), affected strongly the assemblages, reducing diversity both in terms of taxa and functional groups, respect to lower acidification levels (mean pH 7.8) and ambient conditions (8.1 unit). Temporal variation was observed in terms of species composition but not in functional groups. Variability was related to species belonging to the same functional group, suggesting the occurrence of functional redundancy. Therefore, the analysis of functional groups kept information on the structure, but lost information on species diversity and dynamics. Decreasing in ocean pH is only one of many future global changes that will occur at the end of this century (increase of ocean temperature, sea level rise, eutrophication etc.). The interaction between these factors and OA could exacerbate the community and ecosystem effects showed by this thesis.