خيارات البحث
النتائج 441 - 450 من 2,459
Metallothioneins pattern during ontogeny of coastal dolphin, Pontoporia blainvillei, from Argentina
2014
Polizzi, P.S. | Romero, M.B. | Chiodi Boudet, L.N. | Das, K. | Denuncio, P.E. | Rodríguez, D.H. | Gerpe, M.S.
Metallothioneins are signals of metal exposure and widely used in biomonitoring. Franciscana dolphin is an endemic cetacean from the Southwestern Atlantic Ocean, classified as Vulnerable A3d by the IUCN. Metallothionein, copper and zinc in Franciscana were assessed in two geographic groups; one inhabits La Plata River estuary, anthropogenically impacted, and the other inhabits marine coastal ecosystems, with negligible pollution. Despite the environment, hepatic and renal MT concentrations were similar, but there was a declining trend from early to later developmental stages. Metallothionein K/L, Cu and Zn levels corresponded to normal reported ranges. MT was not related with Cd. Fetal concentrations were higher than its mother. These results and the health status of dolphins are suggesting that MT correspond to physiological ranges for the species, and they are closely to homeostasis of Zn and Cu, according to its ontogenetic changes. The information constitutes the first MT information on Franciscana dolphin and can be considered as baseline for the species conservation.
اظهر المزيد [+] اقل [-]Quality assessment of the blue mussel (Mytilus edulis): Comparison between commercial and wild types
2014
De Witte, B. | Devriese, L. | Bekaert, K. | Hoffman, S. | Vandermeersch, G. | Cooreman, K. | Robbens, J.
This study compared species identity, microplastics, chemical and microbial contamination between consumption mussels and wild type mussels, collected at Belgian department stores and Belgian groynes and quaysides, respectively. Species identification based on genetic analysis showed a high number of Mytilus (M.) edulis compared to M. galloprovincialis and M. edulis/galloprovincialis hybrid mussels. The number of total microplastics varied from 2.6 to 5.1fibres/10g of mussel. A higher prevalence of orange fibres at quaysides is related to fisheries activities. Chemical contamination of polycyclic aromatic hydrocarbons and polychlorobiphenyls could be related to industrial activities and water turbidity, with maximum concentrations at the quayside of port Zeebrugge. The inverse was noted for Escherichia coli contamination, which was relatively low at Zeebrugge quayside with a total count of 3.9×102CFU/100g tissue, due to limited agricultural effluents. Results of this complementary analysis stress the importance of integrated monitoring and quality assessment.
اظهر المزيد [+] اقل [-]The invasive kelp Undaria pinnatifida (Laminariales, Ochrophyta) along the north coast of Portugal: Distribution model versus field observations
2014
Veiga, P. | Torres, A.C. | Rubal, M. | Troncoso, J. | Sousa-Pinto, I.
After the first report of Undaria pinnatifida in north Portugal (between 1999 and 2007), a rapid spread of this species could be expected due to the presence of a stable population and the favourable environmental conditions proposed by distribution models. However, field surveys showed that U. pinnatifida was not present in most of the rocky shores in north Portugal. It seems that U. pinnatifida cannot outcompete native species outside of marinas in north Portugal. The only population in natural rocky shores was found in Buarcos, where this species was frequent. This study provides density data of U. pinnatifida that will be useful in the future to monitor changes on its abundance and distribution in the centre and south of Portugal.
اظهر المزيد [+] اقل [-]Sulfonamide antibiotics in the Northern Yellow Sea are related to resistant bacteria: Implications for antibiotic resistance genes
2014
Na, Guangshui | Zhang, Wanru | Zhou, Shiyao | Gao, Hui | Lu, Zihao | Wu, Xian | Li, Ruijing | Qiu, Lina | Cai, Yaqi | Yao, Ziwei
Antibiotic resistance gene (ARG) residues and the mode of transmission in marine environments remain unclear. The sulfonamide (SAs) concentrations, different genes and total bacterial abundance in seawater and sediment of the Northern Yellow Sea were analyzed. Results showed the genes sul I and sul II were present at relatively high concentrations in all samples, whereas the gene sul III was detected fewer. The ARGs concentrations in the sediment were 103 times higher than those in water, which indicated sediment was essential ARG reservoir. Statistical analysis revealed the total antibiotic concentration was positively correlated with the relative abundance of the gene sul I and sul II. The relative abundances of the gene sul I and the gene sul II were also correlated positively with those of the gene int1. This correlation demonstrated that SAs exerted selective pressure on these ARGs, whereas the gene int1 could be implicated in the propagation of the genes sul I and sul II in marine environments.
اظهر المزيد [+] اقل [-]Impacts of recreational motorboats on fishes: A review
2014
Whitfield, A.K. | Becker, A.
A considerable amount of research has been conducted on the impacts of recreational boating activities on fishes but little or no synthesis of the information has been undertaken. This review shows that motor boats impact on the biology and ecology of fishes but the effects vary according to the species and even particular size classes. Direct hits on fishes by propellers are an obvious impact but this aspect has been poorly documented. Alterations in the wave climate and water turbidity may also influence fishes and their habitats, especially submerged and emergent plant beds. Sound generated by boat motors can also influence the communication and behaviour of certain species. Pollution arising from fuel spillages, exhaust emissions and antifouling paints all have detrimental effects on fishes. Finally, the use of recreational boats as vectors of aquatic invasive organisms is very real and has created major problems to the ecology of aquatic systems.
اظهر المزيد [+] اقل [-]Partitioning behavior of perfluorinated compounds between sediment and biota in the Pearl River Delta of South China
2014
Zhao, Y.G. | Wan, H.T. | Wong, M.H. | Wong, Chris K.C.
Surface sediment and biota were collected from 12 sampling sites – seven along the Pearl River Delta and five along the Hong Kong coastline. Perfluorinated compound (PFC) concentrations were detected using a high-performance-liquid-chromatogram–tandem-mass-spectrometry system. Analytical results indicated that the total PFC concentrations were in the range of 0.15–3.11ng/g dry weight in sediments, while the total PFC concentrations in oyster and mussel samples were between 0.46–1.96 and 0.66–3.43ng/g wet weight, respectively. The major types of PFCs detected in the sediment samples were perfluorooctanesulfonic acid (PFOS) and perfluorobutanoic acid (PFBA), with concentrations ranging from low limits of quantification to 0.86±0.12ng/g dry weight and 1.50±0.26ng/g dry weight, respectively. In bivalve samples, PFOS was the dominant contaminant with concentrations ranging from 0.25±0.09 to 0.83±0.12ng/g wet weight in oysters and 0.41±0.14 to 1.47±0.25ng/g wet weight in mussels. An increase in PFC concentration was found to be correlated with increased human population density in the study areas.
اظهر المزيد [+] اقل [-]Could ocean currents be responsible for the west to east spread of aquatic invasive species in Maritime Canadian waters?
2014
Brickman, D.
The circulation in the shelf seas of Maritime Canada is predominantly in the northeast–southwest direction. Despite the mean northeast–southwest flow, a number of AIS invasions have been observed to proceed in the opposite direction – from the Gulf of Maine, around Nova Scotia, and into the southern Gulf of St. Lawrence. Flow fields from a numerical circulation model are used to investigate whether these invasions could be due to drift in ocean currents. Particle tracking experiments are performed and probability density functions (PDFs) derived that describe the probability of drifting a given upstream distance in a given drift time. Analysis of these PDFs revealed that for invasions that took 20–40y to occur, propagule drift in ocean currents could be responsible for the upstream spread, while this was not the case for short timescale invasions (<10y). Rafting could be responsible for both short and long timescale invasions.
اظهر المزيد [+] اقل [-]Large-scale oil spill simulation using the lattice Boltzmann method, validation on the Lebanon oil spill case
2014
Maslo, Aljaž | Panjan, Jože | Žagar, Dušan
This paper tests the adequacy of using the lattice Boltzmann method in large-scale oil spill modelling, such as the Lebanon oil spill. Several numerical experiments were performed in order to select the most appropriate lattice and to decide between the single- and two-relaxation time models. Large-scale oil spills require simulations with short computational times. In order to speed up the computation and preserve adequate accuracy of the model, five different flux limiting interpolation techniques were compared and evaluated. The model was validated on the Lebanon oil spill with regard to the oil-slick position and concentrations in the sea, and the beaching area on the coast. Good agreement with satellite images of the slick and field data on beaching was achieved. The main advantages of the applied method are the capability of simulating very low oil concentrations and computational times that are by an order of magnitude shorter compared to similar models.
اظهر المزيد [+] اقل [-]Development and application of an oil spill model with wave–current interactions in coastal areas
2014
Guo, WeiJun | Hao, Yanni | Zhang, Li | Xu, Tiaojian | Ren, Xiaozhong | Cao, Feng | Wang, Shoudong
The present paper focuses on developing a numerical oil spill model that incorporates the full three-dimensional wave–current interactions for a better representation of the spilled oil transport mechanics in complicated coastal environments. The incorporation of surface wave effects is not only imposing a traditional drag coefficient formulation at the free surface, but also the 3D momentum equations are adjusted to include the impact of the vertically dependent radiation stresses on the currents. Based on the current data from SELFE and wave data from SWAN, the oil spill model utilizes oil particle method to predict the trajectory of individual droplets and the oil concentration. Compared with the observations in Dalian New Port oil spill event, the developed model taking into account wave–current coupling administers to giving better conformity than the one without. The comparisons demonstrates that 3D radiation stress impacts the spill dynamics drastically near the sea surface and along the coastline, while having less impact in deeper water.
اظهر المزيد [+] اقل [-]Interactive effects of hypoxia and polybrominated diphenyl ethers (PBDEs) on microbial community assembly in surface marine sediments
2014
Chan, Yuki | Li, Amy | Gopalakrishnan, Singaram | Shin, Paul K.S. | Wu, Rudolf S.S. | Pointing, Stephen B. | Chiu, Jill M.Y.
Hypoxia alters the oxidation–reduction balance and the biogeochemical processes in sediments, but little is known about its impacts on the microbial community that is responsible for such processes. In this study, we investigated the effects of hypoxia and the ubiquitously dispersed flame-retardant BDE47 on the bacterial communities in marine surface sediments during a 28-days microcosm experiment. Both hypoxia and BDE47 alone significantly altered the bacterial community and reduced the species and genetic diversity. UniFrac analysis revealed that BDE47 selected certain bacterial species and resulted in major community shifts, whereas hypoxia changed the relative abundances of taxa, suggesting slower but nonetheless significant community shifts. These two stressors targeted mostly different taxa, but they both favored Bacteroidetes and suppressed Gammaproteobacteria. Importantly, the impacts of BDE47 on bacterial communities were different under hypoxic and normoxic conditions, highlighting the need to consider risk assessments for BDE47 in a broader context of interaction with hypoxia.
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