خيارات البحث
النتائج 2041 - 2050 من 5,137
Phylogenetic characterization of culturable bacteria and fungi associated with tarballs from Betul beach, Goa, India
2018
Tarballs are semisolid blobs of crude oil, normally formed due to weathering of crude-oil in the sea after any kind of oil spills. Microorganisms are believed to thrive on hydrocarbon-rich tarballs and possibly assist in biodegradation. The taxonomy of ecologically and economically important tarball-associated microbes, however, needs improvement as DNA-based identification and phylogenetic characterization have been scarcely incorporated into it. In this study, bacteria and fungi associated with tarballs from touristic Betul beach in Goa, India were isolated, followed by phylogenetic analyses of 16S rRNA gene and the ITS sequence-data to decipher their clustering patterns with closely-related taxa. The gene-sequence analyses identified phylogenetically diverse 20 bacterial genera belonging to the phyla Proteobacteria (14), Actinobacteria (3), Firmicutes (2) and Bacteroidetes (1), and 8 fungal genera belonging to the classes Eurotiomycetes (6), Sordariomycetes (1) and Leotiomycetes (1) associated with the Betul tarball samples. Future studies employing a polyphasic approach, including multigene sequence-data, are needed for species-level identification of culturable tarball-associated microbes. This paper also discusses potentials of tarball-associated microbes to degrade hydrocarbons.
اظهر المزيد [+] اقل [-]Polycyclic aromatic hydrocarbon (PAH) accumulation in different common sole (Solea solea) tissues from the North Adriatic Sea peculiar impacted area
2018
Frapiccini, Emanuela | Annibaldi, Anna | Betti, Mattia | Polidori, Piero | Truzzi, Cristina | Marini, Mauro
This study extends our knowledge of the bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) in marine organisms and investigates its possible determinants. PAH levels were measured in Solea solea tissue and in marine sediments collected from three areas of the northern Adriatic Sea characterized by different anthropic impacts (Venetian Lagoon, Po Delta, and fishing grounds off Chioggia). The possibility of differential PAH bioaccumulation in different tissues (muscle, liver and gills) was investigated by seeking relationships between mean individual and total PAH concentrations in tissue and sediment samples, the physicochemical properties of PAHs (rings and Kow), and some key biological variables (lipid content of tissues, body size, habitat). The present study demonstrated that the lipid content might not be the only determinant of PAH bioaccumulation in common sole tissues. The habitat characteristics, the tissue types and some physicochemical properties of compounds were closely related to PAH bioaccumulation.
اظهر المزيد [+] اقل [-]A 30-year monitoring of changes in coral community structure following anthropogenic disturbances in Tolo Harbour and Channel, Hong Kong
2018
Coral communities in Tolo Harbour and Channel, northeastern Hong Kong, suffered from tremendous degradations in 1980s due to excessive sewage pollutions. This study examined changes in coral community structures over the last 30 years including period before, at the height of and after implementation of abatement measures of pollution impacts. Signs of coral degradations finally stopped in inner harbour and some corals started to reappear, likely due to sewage export scheme since 1998. Yet, the coral cover remained very low (<2%) in 2012. Natural recovery is limited by very low coral recruitment success other than that of Oulastrea crispata. The outer coral communities, which suffered least in 1980s, continued to decline, possibly due to new biological disturbances like sea urchin predation and bioerosion. This long-term study clearly revealed how coral communities could so easily be destroyed and yet natural recovery could be so difficult and unlikely.
اظهر المزيد [+] اقل [-]Organochlorine pesticides and polychlorinated biphenyls in the Bering flounder (Hippoglossoides robustus) from the Sea of Okhotsk
2018
Lukyanova, Olga N. | Tsygankov, Vasiliy Yu | Boyarova, Margarita D.
The purpose of this study is to establish the presence of POPs in the Bering flounder (Hippoglossoides robustus) from the Sea of Okhotsk (North-West Pacific). Concentration of OCPs (α-HCH, β-HCH, γ-HCH, o,p′-DDT, p,p′-DDT, o,p′-DDD, p,p′-DDD, o,p′-DDE and p,p′-DDE) and PCBs (28, 52, 155, 101, 118, 143, 153, 138, 180, 207) in samples were measured by GC–MS and GC–ECD. The mean OCP concentrations in flounder from East and South areas of the Sea of Okhotsk were 99.8 ± 125.4 and 53.6 ± 40.5 ng/g lipid, respectively; PCB congeners – 112 ± 94.2 and 88.8 ± 50.8 ng/g lipid, respectively. POPs in fish tissue decreased in the order: PCBs > HCHs > DDTs. Our results indicate that consumers will have no health risk due to fish consumption from Sea of Okhotsk. OCP and PCB levels in the Sea of Okhotsk may be considered as background level for the North Pacific.
اظهر المزيد [+] اقل [-]Elevated concentrations of naturally occurring radionuclides in heavy mineral-rich beach sands of Langkawi Island, Malaysia
2018
Khandaker, Mayeen Uddin | Asaduzzaman, Khandoker | Sulaiman, Abdullah Fadil Bin | Bradley, D.A. | Isinkaye, Matthew Omoniyi
Study is made of the radioactivity in the beach sands of Langkawi island, a well-known tourist destination. Investigation is made of the relative presence of the naturally occurring radionuclide ⁴⁰K and the natural-series indicator radionuclides ²²⁶Ra and ²³²Th, the gamma radiation exposure also being estimated. Sample quantities of black and white sand were collected for gamma ray spectrometry, yielding activity concentration in black sands of ²²⁶Ra, ²³²Th and ⁴⁰K from 451±9 to 2411±65Bqkg⁻¹ (mean of 1478Bqkg⁻¹); 232±4 to 1272±35Bqkg⁻¹ (mean of 718Bqkg⁻¹) and 61±6 to 136±7Bqkg⁻¹ (mean of 103Bqkg⁻¹) respectively. Conversely, in white sands the respective values for ²²⁶Ra and ²³²Th were appreciably lower, at 8.3±0.5 to 13.7±1.4Bqkg⁻¹ (mean of 9.8Bqkg⁻¹) and 4.5±0.7 to 9.4±1.0Bqkg⁻¹ (mean of 5.9Bqkg⁻¹); ⁴⁰K activities differed insubstantially from that in black sands, at 85±4 to 133±7Bqkg⁻¹ with a mean of 102Bqkg⁻¹. The mean activity concentrations of ²²⁶Ra and ²³²Th in black sands are comparable with that of high background areas elsewhere in the world. The heavy minerals content gives rise to elevated ²²⁶Ra and ²³²Th activity concentrations in all of black sand samples. Evaluation of the various radiological risk parameters points to values which in some cases could be in excess of recommendations providing for safe living and working. Statistical analysis examines correlations between the origins of the radionuclides, also identifying and classifying the radiological parameters. Present results may help to form an interest in rare-earth resources for the electronics industry, power generation and the viability of nuclear fuels cycle resources.
اظهر المزيد [+] اقل [-]Seasonal dynamics of trace elements in sediment and seagrass tissues in the largest Zostera japonica habitat, the Yellow River Estuary, northern China
2018
Lin, Haiying | Sun, Tao | Adams, Matthew P. | Zhou, Yi | Zhang, Xiaomei | Xu, Shaochun | Gu, Ruiting
Trace element accumulation is an anthropogenic threat to seagrass ecosystems, which in turn may affect the health of humans who depend on these ecosystems. Trace element accumulation in seagrass meadows may vary temporally due to, e.g., seasonal patterns in sediment discharge from upstream areas. In addition, when several trace elements are present in sufficiently high concentrations, the risk of seagrass loss due to the cumulative impact of these trace elements is increased. To assess the seasonal variation and cumulative risk of trace element contamination to seagrass meadows, trace element (As, Cd, Cr, Cu, Pb, Hg, Mn and Zn) levels in surface sediment and seagrass tissues were measured in the largest Chinese Zostera japonica habitat, located in the Yellow River Estuary, at three sites and three seasons (fall, spring and summer) in 2014–2015. In all three seasons, trace element accumulation in the sediment exceeded background levels for Cd and Hg. Cumulative risk to Z. japonica habitat in the Yellow River Estuary, from all trace elements together, was assessed as “moderate” in all three seasons examined. Bioaccumulation of trace elements by seagrass tissues was highly variable between seasons and between above-ground and below-ground biomass. The variation in trace element concentration of seagrass tissues was much higher than the variation in trace element concentration of the sediment. In addition, for trace elements which tended to accumulate more in above-ground biomass than below-ground biomass (Cd and Mn), the ratio of above-ground to below-ground trace element concentration peaked at times corresponding to high water discharge and high sediment loads in the Yellow River Estuary. Overall, our results suggest that trace element accumulation in the sediment may not vary between seasons, but bioaccumulation in seagrass tissues is highly variable and may respond directly to trace elements in the water column.
اظهر المزيد [+] اقل [-]Baseline physio-chemical characteristics of Sydney estuary water under quiescent conditions
2018
Birch, G.F. | Lee, S.B.
The current study establishes baseline water quality properties for Sydney estuary, Australia for long periods of quiescence, which characterize the region. The study was undertaken in response to numerous requests for such data by researchers, government agencies and contractors.During quiescent periods, the range in Secchi depth transparency, turbidity, salinity and total suspended solid (TSS) values was 0.3–5.3 m, 18.6–0.1 NTU, 26.4–35.3 PSU and 8.3–1.0 mg/L in the upper and lower estuary, respectively. Baseline particulate metal concentrations were high, however TSS metal mass was greater during high rainfall.Tables and GIS-based maps allow baseline physio-chemical values to be extracted from the database for any location in Sydney estuary for quiescent conditions. Strong inter-parameter baseline relationships enable interpolation between water quality data. Baseline physio-chemical values were used to assess the impact of a high-precipitation event to demonstrate the utility of the new database.
اظهر المزيد [+] اقل [-]The combined effects of elevated pCO2 and food availability on Tigriopus japonicus Mori larval development, reproduction, and superoxide dismutase activity
2018
Li, Fei | Shi, Jiahui | Cheung, S.G. | Shin, P.K.S. | Liu, Xiaoshou | Sun, Yan | Mu, Fanghong
Previous studies have shown that ocean acidification has little effect on adult Tigriopus japonicus copepods, and mainly impairs the early development and reproduction of females. This study investigated the possible interactive effect between CO2-induced seawater acidification and food availability on larval development and reproductive output in T. japonicus. Copepods were exposed to either pH8.1 or pH7.3 under different food concentrations (0.5×104–80.0×104cells/mL). Both the development of nauplii and copepodites was delayed at pH7.3 with a greater effect at lower food concentrations. The reproductive output followed a bell-shaped curve with the highest reproductive output at food concentrations between 30×104 and 40×104cells/mL. As an indicator of oxidative stress, the activity of superoxide dismutase increased at lower pH, with a greater increase at lower food concentrations. Therefore, the effect of elevated pCO2 on T. japonicus was food dependent.
اظهر المزيد [+] اقل [-]Comparison of mesozooplankton mortality impacted by the cooling systems of two nuclear power plants at the northern Taiwan coast, southern East China Sea
2018
Lee, Pei-Wen | Tseng, Li-Chun | Hwang, Jiang-Shiou
The environmental impact caused by thermal discharge waters of power plants is of global concern since thermal discharge directly affects the environmental situation near power plants. The present study used the vital stain neutral red to identify live and dead zooplankton collected from stations at the intake and the outlet of two nuclear power plants (NPPs). Significantly higher mortalities occurred at the outlet station than at the intake station (p < 0.01) at both NPPs. The mortalities of most zooplankton taxa and all zooplankton assemblages were significantly positive correlated to differences of water temperature (ΔT) at NPP I (p < 0.05), whereas it was not significantly positive correlated with ΔT at NPP II (p > 0.05). The weight of organic matter of zooplankton fragments was higher at the outlet station than at the intake station at both NPPs, indicating the physical damage of zooplankton when passing the cooling system.
اظهر المزيد [+] اقل [-]Effects of sub-seabed CO2 leakage: Short- and medium-term responses of benthic macrofaunal assemblages
2018
Amaro, T. | Bertocci, I. | Queiros, A.M. | Rastelli, E. | Borgersen, G. | Brkljacic, M. | Nunes, J. | Sorensen, K. | Danovaro, R. | Widdicombe, S.
The continued rise in atmospheric carbon dioxide (CO2) levels is driving climate change and temperature shifts at a global scale. CO2 Capture and Storage (CCS) technologies have been suggested as a feasible option for reducing CO2 emissions and mitigating their effects. However, before CCS can be employed at an industrial scale, any environmental risks associated with this activity should be identified and quantified. Significant leakage of CO2 from CCS reservoirs and pipelines is considered to be unlikely, however direct and/or indirect effects of CO2 leakage on marine life and ecosystem functioning must be assessed, with particular consideration given to spatial (e.g. distance from the source) and temporal (e.g. duration) scales at which leakage impacts could occur. In the current mesocosm experiment we tested the potential effects of CO2 leakage on macrobenthic assemblages by exposing infaunal sediment communities to different levels of CO2 concentration (400, 1000, 2000, 10,000 and 20,000 ppm CO2), simulating a gradient of distance from a hypothetic leakage, over short-term (a few weeks) and medium-term (several months). A significant impact on community structure, abundance and species richness of macrofauna was observed in the short-term exposure. Individual taxa showed idiosyncratic responses to acidification. We conclude that the main impact of CO2 leakage on macrofaunal assemblages occurs almost exclusively at the higher CO2 concentration and over short time periods, tending to fade and disappear at increasing distance and exposure time. Although under the cautious perspective required by the possible context-dependency of the present findings, this study contributes to the cost-benefit analysis (environmental risk versus the achievement of the intended objectives) of CCS strategies.
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