خيارات البحث
النتائج 1641 - 1650 من 4,033
Prickly business: abundance of sea urchins on breakwaters and coral reefs in Dubai
2016
Bauman, Andrew G. | Dunshea, Glenn | Feary, David A. | Hoey, Andrew S.
Echinometra mathaei is a common echinoid on tropical reefs and where abundant plays an important role in the control of algal communities. Despite high prevalence of E. mathaei on southern Persian/Arabian Gulf reefs, their abundance and distribution is poorly known. Spatial and temporal patterns in population abundance were examined at 12 sites between breakwater and natural reef habitats in Dubai (UAE) every 3months from 2008 to 2010. Within the breakwater habitat, densities were greatest at shallow wave-exposed sites, and reduced with both decreasing wave-exposure and increasing depth. Interestingly, E. mathaei were significantly more abundant on exposed breakwaters than natural reef sites, presumably due to differences in habitat structure and benthic cover. Population abundances differed seasonally, with peak abundances during summer (July–September) and lower abundances in winter (December–February). Seasonal fluctuations are likely the result of peak annual recruitment pulses coupled with increased fish predation from summer to winter.
اظهر المزيد [+] اقل [-]Study on the cumulative impact of reclamation activities on ecosystem health in coastal waters
2016
Shen, Chengcheng | Shi, Honghua | Zheng, Wei | Li, Fen | Peng, Shitao | Ding, Dewen
The purpose of this study is to develop feasible tools to investigate the cumulative impact of reclamations on coastal ecosystem health, so that the strategies of ecosystem-based management can be applied in the coastal zone. An indicator system and model were proposed to assess the cumulative impact synthetically. Two coastal water bodies, namely Laizhou Bay (LZB) and Tianjin coastal waters (TCW), in the Bohai Sea of China were studied and compared, each in a different phase of reclamations. Case studies showed that the indicator scores of coastal ecosystem health in LZB and TCW were 0.75 and 0.68 out of 1.0, respectively. It can be concluded that coastal reclamations have a historically cumulative effect on benthic environment, whose degree is larger than that on aquatic environment. The ecosystem-based management of coastal reclamations should emphasize the spatially and industrially intensive layout.
اظهر المزيد [+] اقل [-]The role of social marketing, marine turtles and sustainable tourism in reducing plastic pollution
2016
Eagle, Lynne | Hamann, Mark | Low, David R.
Environmental plastic pollution constitutes a significant hazard to marine turtles, human health and well-being. We describe a transdisciplinary approach to draw together findings from diverse disciplines in order to highlight key environmental pollution problems and their consequences, together with social marketing-based strategies to address the problems. The example of plastic pollution and impacts to marine turtles illustrates the severity of the problem. Wildlife tourism and sustainable tourism activity have not focussed on specific behaviours to change and have had minimal impact on subsequent human behaviour regarding environmental issues, indicating the need for new strategies. Social marketing principles offer promise, but there is a need to investigate the utility of various theoretical foundations to aid the design and implementation of interventions. We offer insight towards using sophisticated multi-method research to develop insights into behaviours and segmentation-based strategies, that can aid the identification of barriers to, and enablers of, sustained behaviour change.
اظهر المزيد [+] اقل [-]Application of biological traits to further our understanding of the impacts of dredged material disposal on benthic assemblages
2016
Bolam, S.G. | McIlwaine, P.S.O. | Garcia, C.
While the effects of coastal disposal of dredged material on benthic assemblage structure have been well studied, our understanding of the mechanism of such responses, and their potential ecological implications, remain relatively unknown. Data from a licenced disposal site off the northeast coast of England are analysed to address this and improve our ability to make informed licencing decisions for this activity. Assemblages within the disposal site displayed reduced number of species and total invertebrate density, an altered assemblage taxonomic structure, and a shift towards a greater numerical dominance of less-productive individuals. Following separate analyses of biological response and effect traits, a novel approach for marine benthic trait analysis, we identify the traits responsible (i.e. response traits) for the observed structural alterations. Furthermore, analysis of the effect traits revealed that the assemblages characterising the disposal site possess a greater bioturbative capability compared to those not directly impacted by disposal.
اظهر المزيد [+] اقل [-]Weathering of field-collected floating and stranded Macondo oils during and shortly after the Deepwater Horizon oil spill
2016
Stout, Scott A. | Payne, James R. | Emsbo-Mattingly, Stephen D. | Baker, Gregory
Chemical analysis of large populations of floating (n=62) and stranded (n=1174) Macondo oils collected from the northern Gulf of Mexico sea surface and shorelines during or within seven weeks of the end of the Deepwater Horizon oil spill demonstrates the range, rates, and processes affecting surface oil weathering. Oil collected immediately upon reaching the sea surface had already lost most mass below n-C8 from dissolution of soluble aliphatics, monoaromatics, and naphthalenes during the oil's ascent with further reductions extending up to n-C13 due to the onset of evaporation. With additional time, weathering of the floating and stranded oils advanced with total PAH (TPAH50) depletions averaging 69±23% for floating oils and 94±3% for stranded oils caused by the combined effects of evaporation, dissolution, and photo-oxidation, the latter of which also reduced triaromatic steroid biomarkers. Biodegradation was not evident among the coalesced floating oils studied, but had commenced in some stranded oils.
اظهر المزيد [+] اقل [-]Validation of a new and cost-effective method for mercury vapor removal based on silver nanoparticles coating on micro glassy balls
2016
Shirkhanloo, Hamid | Osanloo, Mahmood | Ghazaghi, Mehri | Hassani, Hamid
Exposure to mercury vapor (Hg0) causes serious health problem in human body. In this study, a novel and applied method based on solid gas phase extraction (SGPE) with silver nanoparticles (AgNPs) coating on micro glassy balls (MGB) was used for Hg0 removal from artificial air. In bench scale set up, the mercury vapor in air composition was produced by mercury vapor generation system (HgGS) and restored in polyethylene air bag (5 Li). In optimized conditions, the mercury vapor in air bag, passed through AgNPs-MGB and absorbed on it. Then, the mercury was completely desorbed from AgNPs by increasing temperature up to 245 °C and online determined by cold vapor atomic absorption spectrometry (CV-AAS). By proposed procedure, the method recovery and capacity of AgNPs were obtained 98% and 91.8 mg g−1, respectively. A simple, fast and low cost synthesis of AgNPs causes, the SGPE introduce as a cost-effective method for mercury vapor removal from air. Validation of methodology was confirmed using ultra trace mercury analyzer (MC3000).
اظهر المزيد [+] اقل [-]Spatio-temporal distributions of chlorofluorocarbons and methyl iodide in the Changjiang (Yangtze River) estuary and its adjacent marine area
2016
Yuan, Da | Yang, Gui-Peng | He, Zhen
Temporal and spatial distribution patterns of volatile halogenated organic compounds (VHOCs), such as dichlorodifluoromethane (CFC-12), trichlorofluoromethane (CFC-11), trichlorotrifluoroethane (CFC-113), and methyl iodide (CH3I), in the Changjiang (Yangtze River) estuary and its adjacent marine area were measured during two cruises from 21 February to 10 March 2014 and from 10 to 21 July 2014. VHOC concentrations showed seasonal variation with higher values during winter. VHOC distributions evidently decreased along the freshwater plume from the river mouth to the open sea and from inshore to offshore regions. VHOC distributions were obviously influenced by the Changjiang runoff, anthropogenic inputs, and biological release of phytoplankton. The study area was a net sink for CFC-12 and CFC-11, but a net source for atmospheric CH3I during the study periods.
اظهر المزيد [+] اقل [-]A study of oxidative stress induced by two polybrominated diphenyl ethers in the rotifer Brachionus plicatilis
2016
Zhang, Jing | Wang, You | Sun, Kai-Ming | Fang, Kuan | Tang, Xuexi
Polybrominated diphenyl ethers (PBDEs) are widely dispersed persistent organic pollutants in the marine ecosystem. However, their toxic mechanisms in marine organisms, especially invertebrates, remain poorly understood. Two common congeners of PBDEs, tetrabrominated diphenyl ether-47 (BDE-47) and decabrominated diphenyl ether-209 (BDE-209), were investigated. Their toxic mechanisms, with a focus on oxidative stress, were examined in rotifer Brachionus plicatilis. Overproduction of reactive oxygen species (ROS) was induced by two PBDEs. The expression of superoxide dismutase (SOD) mRNA was increased, suggesting SOD play a main role in ROS-scavenging. The intercellular concentrations of calcium ([Ca2+]in) and the expression of calmodulin (CaM) mRNA were increased. This indicates the calcium ion (Ca2+) signaling channel is involved in PBDEs stress. Further analysis showed that the reproductive system might be the target site for toxicity of PBDEs. Moreover, high value of detection indexes in BDE-47 experimental groups suggested BDE-47 might cause higher oxidative damage than BDE-209 in rotifers.
اظهر المزيد [+] اقل [-]Detection and risk assessment of diarrheagenic E. coli in recreational beaches of Brazil
2016
Rodrigues, Vanessa F.V. | Rivera, Irma N.G. | Lim, Keah-Ying | Jiang, Sunny C.
Marine beaches are important recreational and economic resources in Brazil, but the beaches' water quality is negatively impacted by the discharge of domestic sewage effluent. The occurrence of diarrheagenic Escherichia coli among the E. coli isolated from three Brazilian marine beaches was investigated. Multiplex and single step PCR were used to screen 99 E. coli isolates for ten target toxin genes. Six toxin genes, stx1, eae, estp, esth, astA, and bfpA, were identified in 1% to 35% of the isolates. A quantitative microbial risk assessment (QMRA) of human exposure to diarrheagenic E. coli during marine recreation was carried out. The results indicated that the diarrheagenic E. coli risk is well below the U.S. EPA's recommended daily recreational risk benchmark. However, the overall recreational health risk due to all pathogens in the water could be much higher and exceeded the U.S. EPA's benchmark.
اظهر المزيد [+] اقل [-]Active biomonitoring of mussels Mytilus galloprovincialis with integrated use of micronucleus assay and physiological indices to assess harbor pollution
2016
Gherras Touahri, Hamida | Boutiba, Zitouni | Benguedda, Wacila | Shaposhnikov, Sergey
The mussels Mytilus galloprovincialis collected from a noncontaminated site (Chaib Rasso) were transplanted during one, three and six months at Ghazaouet harbor (GH), areas with a strong gradient of pollution. The micronucleus test (MN) was selected to monitor the impact of contamination, along with physiological indexes (condition index CI and organo-somatic indexes RI and GSI). The results show a negative correlation of MN variation in gill cells with CI but a positive correlation with transplantation duration. However, a significant correlation was found between the indexes. Moreover, the findings indicate that MN in the hemolymph and gills of transplanted mussels for one, three and six months at GH are significantly higher than those of the reference site. However, no significant differences were noted between the three transplants at the two organs. Monitoring the physiological status of mussels, in parallel with the biomarker measurements, is useful in assessing the impact of contaminants.
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