خيارات البحث
النتائج 581 - 590 من 3,243
Evidencing the natural and anthropogenic processes controlling trace metals dynamic in a highly stratified estuary: The Krka River estuary (Adriatic, Croatia)
2015
Cindrić, Ana-Marija | Garnier, Cédric | Oursel, Benjamin | Pižeta, Ivanka | Omanović, Dario
Distributions of trace metals (TM), organic carbon, SPM and physico-chemical parameters were studied in the highly stratified Krka River estuary in winter/summer periods. The non-conservative behaviour of Zn, Cd, Pb and Cu in the brackish layer (plume), easily spotted due to very low inputs by the river, was mainly caused by their inputs from the pleasure boats, nautical marinas and harbour (e.g. release from antifouling paints). Contrarily, Ni and Co followed near-conservative behaviour. The extremely low SPM discharged by the river, resulted in a predominant dissolved fraction (>80%) of all TM, except Pb. Vertical scavenging, coupled with the long residence time, caused accumulation and progressive upstream increase of TM and SPM in the bottom seawater. Decrease of distribution coefficient (KD) in the brackish layer for winter period was ascribed to the change of SPM nature (terrestrial vs. biogenic), whereas a variable and increased biogenic component of SPM caused scattered KDs in summer.
اظهر المزيد [+] اقل [-]Use of multiple cell and tissue-level biomarkers in mussels collected along two gas fields in the northern Adriatic Sea as a tool for long term environmental monitoring
2015
Gomiero, A. | Volpato, E. | Nasci, C. | Perra, G. | Viarengo, A. | Dagnino, A. | Spagnolo, A. | Fabi, G.
As a consequence of the growing global demand of energy supplies, intense oil and gas exploration and exploitation programs have been carried out worldwide especially within the marine environments. The release of oil-derived compounds in the sea from anthropogenic sources both as effluents or accidental spill is perceived as a major environmental concern. An approach based on a combination of biomarkers and the distribution of some classes of environmentally relevant pollutants was used to investigate the occurrence of a stress syndrome in mussels (Mytilus galloprovincialis) collected at three gas platforms placed in two distinct oceanographic districts within the Adriatic Sea. Biological responses were integrated by a ranking algorithm which demonstrated both a range of biological effects reflecting exposure gradients and a temporal related trend in the investigated responses. The overall results demonstrate a moderate to absent pollution from studied gas platforms with low but remarkable biological disturbance in sentinel organisms.
اظهر المزيد [+] اقل [-]Assessment of the European flounder responses to chemical stress in the English Channel, considering biomarkers and life history traits
2015
Dupuy, Célie | Galland, Claire | Pichereau, Vianney | Sanchez, Wilfried | Riso, Ricardo | Labonne, Maylis | Amara, Rachid | Charrier, Grégory | Fournier, Michel | Laroche, Jean
A multi-biomarker approach was developed to evaluate responses of European flounder (Platichthys flesus) in three contrasted estuaries over the English Channel: the Canche (pristine site), Tamar (heavy metals and PAHs contamination) and Seine (heavily pollution with a complex cocktail of contaminants). The condition factor and several biomarkers of the immune system, antioxidant enzymes, energetic metabolism and detoxification processes were investigated in young-of-the-year (0+) and one-year-old (1+) flounder. Results underlined the difference between the pristine site and the Seine estuary which showed a lower condition factor, a modulation of the immune system, a higher Cytochrome C oxidase activity, and an up-regulation of BHMT expression. The moderate biomarker responses in the Tamar fish could be linked to the specific contamination context of this estuary. Flounder life history traits were analyzed by otolith microchemistry, in order to depict how the fish use their habitat and thus respond to chemical stress in estuaries.
اظهر المزيد [+] اقل [-]The use of flow cytometric applications to measure the effects of PAHs on growth, membrane integrity, and relative lipid content of the benthic diatom, Nitzschia brevirostris
2015
Croxton, April N. | Wikfors, Gary H. | Schulterbrandt-Gragg, Richard D.
This laboratory study measured the direct effects of three polycyclic aromatic hydrocarbon (PAH) compounds (naphthalene, pyrene, and benzo(a)pyrene) upon cell growth, membrane integrity, and BODIPY-stained lipid fluorescence intensity of the benthic diatom Nitzschia brevirostris using flow cytometry as an analysis tool. Previous field and laboratory studies have reported reductions in algal populations following PAH exposure, but specific, functional responses of the microalgae to these pollutants could not be revealed by cell numbers alone. Using flow-cytometric measurements, we confirmed that maximal cell densities in PAH-exposed diatom cultures were significantly lower compared to controls; however, we also discovered increases in lipids and cells with compromised membranes in PAH-exposed cultures. These results highlight new tools for measuring the direct effects of organic pollutants upon the physiology of taxa comprising microphytobenthic communities important in estuarine food webs.
اظهر المزيد [+] اقل [-]A framework for the resilience of seagrass ecosystems
2015
Unsworth, Richard K.F. | Collier, Catherine J. | Waycott, Michelle | Mckenzie, Len J. | Cullen-Unsworth, Leanne C.
Seagrass ecosystems represent a global marine resource that is declining across its range. To halt degradation and promote recovery over large scales, management requires a radical change in emphasis and application that seeks to enhance seagrass ecosystem resilience. In this review we examine how the resilience of seagrass ecosystems is becoming compromised by a range of local to global stressors, resulting in ecological regime shifts that undermine the long-term viability of these productive ecosystems. To examine regime shifts and the management actions that can influence this phenomenon we present a conceptual model of resilience in seagrass ecosystems. The model is founded on a series of features and modifiers that act as interacting influences upon seagrass ecosystem resilience. Improved understanding and appreciation of the factors and modifiers that govern resilience in seagrass ecosystems can be utilised to support much needed evidence based management of a vital natural resource.
اظهر المزيد [+] اقل [-]Organochlorine contaminants and maternal offloading in the lecithotrophic Pacific angel shark (Squatina californica) collected from southern California
2015
Lyons, Kady | Lowe, Christopher G.
Pacific angel sharks (Squatina californica) are a benthic elasmobranch that occupy intermediate trophic level positions in coastal food webs. Angel sharks’ life history characteristics make them susceptible to accumulating high amounts of contaminants. Four angel sharks were opportunistically captured in southern California and their liver and uterine contents were analyzed for PCBs, DDTs and other pesticides. High DDT:PCB ratios were found in the sharks indicating direct or indirect foraging near a local EPA Superfund Site. Organic contaminants were measured in ovulated eggs, indicating that females are able to maternally offload contaminants. Despite the potential mismatch between ovarian and uterine fecundity, we estimated females to offload approximately 13±5% of their total body load, which represents the upper limit of this capability. Although low in sample size, the initial findings from this study suggest that habitat use might play an important role in contaminant accumulation in this species.
اظهر المزيد [+] اقل [-]Informing Marine Spatial Planning (MSP) with numerical modelling: A case-study on shellfish aquaculture in Malpeque Bay (Eastern Canada)
2015
Filgueira, Ramón | Guyondet, T. | Bacher, Cédric | Comeau, Luc A.
A moratorium on further bivalve leasing was established in 1999–2000 in Prince Edward Island (Canada). Recently, a marine spatial planning process was initiated explore potential mussel culture expansion in Malpeque Bay. This study focuses on the effects of a projected expansion scenario on productivity of existing leases and available suspended food resources. The aim is to provide a robust scientific assessment using available datasets and three modelling approaches ranging in complexity: (1) a connectivity analysis among culture areas; (2) a scenario analysis of organic seston dynamics based on a simplified biogeochemical model; and (3) a scenario analysis of phytoplankton dynamics based on an ecosystem model. These complementary approaches suggest (1) new leases can affect existing culture both through direct connectivity and through bay-scale effects driven by the overall increase in mussel biomass, and (2) a net reduction of phytoplankton within the bounds of its natural variation in the area.
اظهر المزيد [+] اقل [-]Environmental triggers for primary outbreaks of crown-of-thorns starfish on the Great Barrier Reef, Australia
2015
Wooldridge, Scott A. | Brodie, J. E. (Jon E.)
In this paper, we postulate a unique environmental triggering sequence for primary outbreaks of crown-of-thorns starfish (COTS, Acanthaster planci) on the central Great Barrier Reef (GBR, Australia). Notably, we extend the previous terrestrial runoff hypothesis, viz. nutrient-enriched terrestrial runoff→elevated phytoplankton ‘bloom’ concentrations→enhanced COTS larval survival, to include the additional importance of strong larvae retention around reefs or within reef groups (clusters) that share enhanced phytoplankton concentrations. For the central GBR, this scenario is shown to occur when El Niño-Southern Oscillation (ENSO) linked hydrodynamic conditions cause the ‘regional’ larval connectivity network to fragment into smaller ‘local’ reef clusters due to low ocean current velocities. As inter-annual variations in hydrodynamic circulation patterns are not amenable to direct management intervention, the ability to reduce the future frequency of COTS outbreaks on the central GBR is shown to be contingent on reducing terrestrial bioavailable nutrient loads ~20–40%.
اظهر المزيد [+] اقل [-]Residents’ perception of air quality, pollution sources, and air pollution control in Nanchang, China
2015
Liao, Xiong | Tu, Hong | Maddock, Jay E. | Fan, Si | Lan, Guilin | Wu, Yanyan | Yuan, Zhao Kang | Lu, Yuanan
To assess the public's understanding of the main sources of air pollution in Nanchang and factors influencing their perceptions of Nanchang's air quality status, a face–to–face survey data was collected at the provincial children's hospital and four kindergarten classes in Nanchang. A total of 989 parents with children between the ages of 2 to 10 years old participated in the survey. Among which 69% of respondents believed that the current air quality was worse than three years ago. This study reveals that parents who were under 40 years old of age with higher education level and international travel experience, had higher level awareness of air pollution. Men tend to have lower knowledge of air pollution as compared to women. The top three selected sources of air pollution were motor vehicles (78.5%), waste burning (56.3%) and industrial facilities (53.7%). In addition, 79.8% of respondents believed that the government did not spend enough on environmental protection and 96.8% suggested to increase government funding to improve air quality. The majority of respondents (>90%) strongly urges the Nanchang government to prioritize environmental protection. The findings from this study suggest the need for the government to improve the awareness of the main sources of air pollution, especially to residents of rural areas with lower levels of education, to more effectively and efficiently control air pollution in Nanchang.
اظهر المزيد [+] اقل [-]Mediterranean marine biodiversity under threat: Reviewing influence of marine litter on species
2015
Deudero, Salud | Alomar, Carme
The Mediterranean Sea is one of the most polluted seas worldwide, especially with regard to plastics. The presence of this emerging man made contaminant in marine environments precludes large effects and interactions with species exposed to massive litter quantities. In this review, available data of floating and seafloor litter around Mediterranean sub-basins are reported. A review of scientific literature on the interaction of plastic with marine biota resulted in the identification of 134 species, several taxa and feeding strategies affected from 1986 to 2014. Data from 17,334 individuals showed different levels of ingestion and effects on catalogued IUCN species (marine mammals and sea turtles) in addition to several pelagic fish and elasmobranchs. Biodiversity is certainly under threat, and knowledge of the extent of taxa affected is of concern considering the increasing plastic loads in the Mediterranean Sea and worldwide.
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