خيارات البحث
النتائج 491 - 500 من 1,301
Macroalgal diversity along the Baltic Sea salinity gradient challenges Remane’s species-minimum concept
2011
Schubert, Hendrik | Feuerpfeil, Peter | Marquardt, Ronny | Telesh, Irena | Skarlato, Sergei
Remane’s species-minimum concept, which states that the lowest number of taxa occurs at the horohalinicum (5–8psu), was tested by investigating macroalgal diversity on hard substrates along the natural salinity gradient in the Baltic Sea. Field data on species occurrence and abundance were collected by SCUBA diving along 10 transects of the Finnish, Swedish and German coasts, covering a salinity range from 3.9 to 27psu. Macroalgal species numbers declined steadily with salinity, decreasing until 7.2psu was reached, but in the horohalinicum, a marked reduction of species number and a change in diversity were indicated by the Shannon index and evenness values. The non-linear decrease in macroalgal diversity at 5–8psu and the lack of increase in species numbers at salinities below 5psu imply a restricted applicability of Remane’s species-minimum concept to macroalgae.
اظهر المزيد [+] اقل [-]Hydrocarbon composition and distribution in a coastal region under influence of oil production in northeast Brazil
2011
Wagener, Angela de L.R. | Carreira, Renato S. | Hamacher, Claudia | Scofield, Arthur de L. | Farias, Cassia O. | Cordeiro, Lívia G.M.S. | Luz, Letícia G. | Baêta, Aída P. | Kalas, Francine A.
Waters and sediments from the Potiguar Basin (NE Brazilian coast) were investigated for the presence and nature of polycyclic aromatic hydrocarbons (PAH) and aliphatic hydrocarbons. The region receives treated produced waters through a submarine outfall system serving the industrial district. The total dispersed/dissolved concentrations in the water column ranged from 10–50ngL⁻¹ for ∑16PAH and 5–10μgL⁻¹ for total aliphatic hydrocarbons. In the sediments, hydrocarbon concentrations were low (0.5–10ngg⁻¹for ∑16PAH and 0.01–5.0μgg⁻¹ for total aliphatic hydrocarbons) and were consistent with the low organic carbon content of the local sandy sediments. These data indicate little and/or absence of anthropogenic influence on hydrocarbon distribution in water and sediment. Therefore, the measured values may be taken as background values for the region and can be used as future reference following new developments of the petroleum industry in the Potiguar Basin.
اظهر المزيد [+] اقل [-]Heavy metal concentrations and biomarkers of oxidative stress in native mussels (Mytilus edulis chilensis) from Beagle Channel coast (Tierra del Fuego, Argentina)
2011
Duarte, Claudia A. | Giarratano, Erica | Amin, Oscar A. | Comoglio, Laura I.
The aim of this study was to evaluate the usefulness of oxidative stress biomarkers of pollution in native mussels Mytilus edulis chilensis from the Beagle Channel. Spatial and seasonal variations of catalase, glutathione-S-transferase and lipid peroxidation in gills and digestive gland were analyzed in relation to environmental parameters, heavy metals in sediment and in tissue. Four sites with anthropogenic impact and a control site were selected and monitored during the four seasons of 2007. We found significant differences among sites in concentrations of dissolved nutrients and heavy metals in sediments, with the highest values recorded at sites with anthropogenic pressure. Different patterns were observed between concentrations of metals in tissues and in sediments suggesting differences in bioavailability. There were also significant differences in biomarker responses among sites, despite the strong seasonal variability. Our results showed relatively moderate levels of pollution in the study area as a result of urban influences.
اظهر المزيد [+] اقل [-]Sorption behavior of phenanthrene in Yangtze estuarine sediments: Sequential separation
2011
Yang, Yi | Liu, Min | Wang, Lili | Fu, Jialu | Yan, Caixia | Zhou, John L.
In the present study, phenanthrene was chosen as the probe compound for determining the sorption of PAHs in sediments from Yangtze estuary and nearby coastal area, China. Sorption isotherms were fitted well by the Freundlich and dual models, respectively. Selected sediments were further sequentially separated to remove the carbonate and organic carbon (OC). Calculated OC sorption capacity values based on both H₂O₂ oxidization and 375°C combustion methods were similar and comparable to the Kₒc values estimated by the empirical linear sorption equations. Both sorption models and sorption data using sequentially separated samples achieve the similar conclusions: (1) the partition behavior dominated by OC in sediments with fₒc>0.01; (2) for sediments with 0.001<fₒc<0.01, OC dominated sorption at relatively high aqueous concentration; whereas mineral phase adsorption dominated sorption at lower concentration especially when Cw/Sw was in the range of 0.0001–0.001 in natural aqueous system.
اظهر المزيد [+] اقل [-]The impact of dredge-fill on Posidonia oceanica seagrass meadows: Regression and patterns of recovery
2011
Badalamenti, Fabio | Alagna, Adriana | D’Anna, Giovanni | Terlizzi, Antonio | Di Carlo, Giuseppe
Posidonia oceanica meadows can be severely damaged by dredge-fill operations. We report on the construction of gas pipelines that occurred between 1981 and 1993 in SW Sicily, Italy. A large portion of the meadow was mechanically removed, and the excavated trench was filled with a mosaic of substrates, ranging from sand to consolidated rock debris. Meadow loss and recovery were quantified over 7years after the end of operations. We recorded an overall loss of 81.20ha of meadow. Substrate strongly affected recovery as the percent cover by P. oceanica consistently increased on calcareous rubble, reaching values of 44.37±3.05% in shallow sites after 7years, whereas no significant increase occurred on other substrates. As in the Mediterranean Sea exploitation of coastal areas continues to grow with consequent impacts on P. oceanica meadows, this case study illustrates how artificial rubble-like materials could be employed to support the restoration of damaged meadows.
اظهر المزيد [+] اقل [-]Hazardous and Noxious Substances (HNS) in the marine environment: Prioritizing HNS that pose major risk in a European context
2011
Neuparth, T. | Moreira, S. | Santos, M.M. | Reis-Henriques, M.A.
Increases in the maritime transportation of Hazardous and Noxious Substances (HNS), alongside the need for an effective response to HNS spills have led environmental managers and the scientific community to focus attention on HNS spill preparedness and responsiveness. In the context of the ARCOPOL project, a weight-of-evidence approach was developed aimed at prioritizing HNS that pose major environmental risks to European waters. This approach takes into consideration the occurrence probability of HNS spills in European Atlantic waters and the severity of exposure associated with their physico-chemical properties and toxicity to marine organisms. Additionally, a screening analysis of the toxicological information available for the prioritization of HNS was performed. Here we discuss the need for a prioritization methodology to select HNS that are likely to cause severe marine environmental effects as an essential step towards the establishment of a more effective preparedness and response to HNS incidents.
اظهر المزيد [+] اقل [-]Integrated biomarker assessment of the effects exerted by treated produced water from an onshore natural gas processing plant in the North Sea on the mussel Mytilus edulis
2011
Brooks, Steven | Harman, Chris | Zaldibar, Beñat | Izagirre, Urtzi | Glette, Tormod | Marigómez, Ionan
The biological impact of a treated produced water (PW) was investigated under controlled laboratory conditions in the blue mussel, Mytilus edulis. Mussel health status was assessed using an integrated biomarker approach in combination with chemical analysis of both water (with SPMDs), and mussel tissues. Acyl-CoA oxidase activity, neutral lipid accumulation, catalase activity, micronuclei formation, lysosomal membrane stability in digestive cells and haemocytes, cell-type composition in digestive gland epithelium, and the integrity of the digestive gland tissue were measured after 5week exposure to 0%, 0.01%, 0.1%, 0.5% and 1% PW. The suite of biomarkers employed were sensitive to treated PW exposure with significant sublethal responses found at 0.01–0.5% PW, even though individual chemical compounds of PW were at extremely low concentrations in both water and mussel tissues. The study highlights the benefits of an integrated biomarker approach for determining the potential effects of exposure to complex mixtures at low concentrations. Biomarkers were integrated in the Integrative Biological Response (IBR/n) index.
اظهر المزيد [+] اقل [-]Induction of tributyltin-binding protein type 2 in Japanese flounder, Paralichthys olivaceus, by exposure to tributyltin-d27
2011
Nassef, Mohamed | Tawaratsumita, Takahiko | Oba, Yumi | Satone, Hina | Nakayama, Kei | Shimasaki, Yohei | Honjo, Tsuneo | Ōshima, Yūji
In this study, individual Japanese flounder were intraperitoneally injected with 2μg tributyltin-d27 (TBT-d27) fish⁻¹. Blood samples were collected on day 7 after injection. TBT-binding protein types 1 and 2 (TBT-bp1, -bp2) in the blood serum were quantified by western blotting analysis. As a result, the concentration of TBT-bp2 in TBT-d27 treated group increased to 220% of that in the solvent control, whereas the TBT-bp1 concentration decreased to 65% of that in the solvent control. Additionally, a positive relationship between the concentrations of TBT-bp2 and TBT was observed in blood sera of wild and cultured flounder. We suggest that TBT-bp2 is produced in response to TBT exposure and may play an important role in fish physiology.
اظهر المزيد [+] اقل [-]Arsenic and trace metal contents in sediment profiles from the Admiralty Bay, King George Island, Antarctica
2011
Ribeiro, Andreza P. | Figueira, Rubens C.L. | Martins, César C. | Silva, Charles R.A. | França, Elvis J. | Bícego, Márcia C. | Mahiques, Michel M. | Montone, Rosalinda C.
Admiralty Bay (Antarctica) hosts three scientific stations (Ferraz, Arctowski and Macchu Picchu), which require the use of fossil fuel as an energy source. Fossil fuels are also considered the main source of pollution in the area, representing important inputs of major pollutants (organic compounds) and trace metals and metalloids of environmental interest. Accordingly, this work presents the results of As, Cd, Cr, Cu, Ni, Pb and Zn in sediment profiles from Admiralty Bay. The sediment results from Ferraz station were slightly higher than the other sampling sites. The highest contents were observed for Cu and Zn (from 44 to 89mgkg⁻¹). Otherwise, by using enrichment factors and geochronology analysis, the most relevant enrichment was observed for As in the samples collected close to the Ferraz station, indicating that increasing As content may be associated with the activities associated with this site.
اظهر المزيد [+] اقل [-]Can pharmaceuticals interfere with the synthesis of active androgens in male fish? An in vitro study
2011
Fernandes, Denise | Schnell, Sabine | Porte, Cinta
The in vitro interference of fibrate (gemfibrozil, clofibrate, clofibric acid), anti-inflammatory (ibuprofen, diclofenac), and anti-depressive (fluoxetine, fluvoxamine) drugs with key enzymatic activities—C17,20-lyase and CYP11β-involved in the synthesis of active androgens in gonads of male carp have been investigated. Among the tested compounds, fluvoxamine and fluoxetine were the strongest inhibitors of C17,20-lyase and CYP11β enzymes, with IC50s in the range of 321–335μM and 244–550μM, respectively. To our knowledge this is the first report on the interaction of pharmaceutical compounds with enzymatic systems involved in the synthesis of oxy-androgens. As oxy-androgens are known to influence spermatogenesis and stimulate reproductive behavior and secondary sexual characteristics in male fish, this work highlights the need for further investigating these endpoints when designing specific in vivo studies to assess the endocrine disruptive effect of pharmaceuticals in fish.
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