خيارات البحث
النتائج 1201 - 1210 من 3,991
The Sea of Okhotsk and the Bering Sea as the region of natural aquaculture: Organochlorine pesticides in Pacific salmon
2016
Tsygankov, Vasiliy Yu | Lukyanova, Olga N. | Khristoforova, Nadezhda K.
Kuril Islands of the Sea of Okhotsk and the western part of the Bering Sea are an area of natural feeding of Pacific salmon, and the catch area of ones for food market. Food safety of products is an important task of aquaculture. Сoncentrations of HCHs (α-, β-, γ-) and DDT and its metabolites (DDD and DDE) were determined in organs of the pink (Oncorhynchus gorbuscha), chum (O. keta), chinook (O. tshawytscha), and sockeye (O. nerka), which caught from the natural aquaculture region of Russia (near the Kuril Islands (the northern-western part of the Pacific Ocean), the Sea of Okhotsk and the Bering Sea). The average total concentration of OCPs in organs of salmon from Western Pacific is lower than that in salmon from the North Pacific American coast and the Atlantic Ocean. The region can be used to grow smolts, which will be later released into the ocean.
اظهر المزيد [+] اقل [-]Spatial variability in persistent organic pollutants and polycyclic aromatic hydrocarbons found in beach-stranded pellets along the coast of the state of São Paulo, southeastern Brazil
2016
Taniguchi, Satie | Colabuono, Fernanda I. | Dias, Patrick S. | Oliveira, Renato | Fisner, Mara | Turra, Alexander | Izar, Gabriel M. | Abessa, Denis M.S. | Saha, Mahua | Hosoda, Junki | Yamashita, Rei | Takada, Hideshige | Lourenço, Rafael A. | Magalhães, Caio A. | Bícego, Márcia C. | Montone, Rosalinda C.
High spatial variability in polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), organochlorine pesticides, such as DDTs, and polybrominated diphenylethers was observed in plastic pellets collected randomly from 41 beaches (15 cities) in 2010 from the coast of state of São Paulo, southeastern Brazil. The highest concentrations ranged, in ng g−1, from 192 to 13,708, 3.41 to 7554 and <0.11 to 840 for PAHs, PCBs and DDTs, respectively. Similar distribution pattern was presented, with lower concentrations on the relatively less urbanized and industrialized southern coast, and the highest values in the central portion of the coastline, which is affected by both waste disposal and large port and industrial complex. Additional samples were collected in this central area and PCB concentrations, in ngg−1, were much higher in 2012 (1569 to 10,504) than in 2009/2010 (173 to 309) and 2014 (411), which is likely related to leakages of the PCB commercial mixture.
اظهر المزيد [+] اقل [-]Assessment of factors enabling halite formation in a marsh in a humid temperate climate (Ajó Marsh, Argentina)
2016
Carol, Eleonora S. | Álvarez, María del Pilar | Borzi, Guido E.
The formation of evaporites associated with the final stages of the precipitation sequence, such as the case of halite, is frequent in marshes in arid areas, but it is not to be expected in those humid climates. This work, by means of the study of the hydrological, climatic and land use conditions, identifies the factors that allow the formation of saline precipitations in a marsh located in a humid climate area. The results obtained show that the exclusion of the marsh as a result of the embankment is the main reason for the presence of halite. It is to be expected that in the future the growth of the embanked marsh areas, together with the climatic and tidal condition tendencies recorded, will favour a higher rate of formation of evaporite salts. The identification of these factors makes it possible to set basic sustainable management guidelines to avoid soil salinisation.
اظهر المزيد [+] اقل [-]Microbial community structure shifts are associated with temperature, dispersants and nutrients in crude oil-contaminated seawaters
2016
Meng, Long | Liu, Han | Bao, Mutai | Sun, Peiyan
This study tracked structure shifts of bacterial compositions before, during and after invading by crude oil to determine the microbial response and explore how temperature, dispersants and nutrients affect the composition of microbial communities or their activities of biodegradation in artificial marine environment. During petroleum hydrocarbons exposed, the composition and functional dynamics of marine microbial communities were altered, favoring bacteria that could utilize this rich carbon source such as the Proteobacteria, Firmicutes, Actinobacteria and Bacteroidetes phyla. Low temperature as a dominant factor decreased bacterial richness and catabolic diversity due to abated enzymes activities in correlation with the process of biodegradation. Dispersants exerted no negative consequences on microbial composition, however, bacterial composition by the Chloroflexi, TM6, OP8, Cyanobacteria and Gemmatimonadetes phyla increased. It seemed that more frequent fertilizer application could be equally safe to bacteria and increased significantly the abundance of bacterial strains but Actinobacteria phyla decreased.
اظهر المزيد [+] اقل [-]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 [-]Regional variation in the structure and function of parrotfishes on Arabian reefs
2016
Hoey, Andrew S. | Feary, David A. | Burt, John A. | Vaughan, Grace | Pratchett, Morgan S. | Berumen, Michael L.
Parrotfishes (f. Labridae) are a unique and ubiquitous group of herbivorous reef fishes. We compared the distribution and ecosystem function (grazing and erosion) of parrotfishes across 75 reefs in Arabia. Our results revealed marked regional differences in the abundance, and taxonomic and functional composition of parrotfishes between the Red Sea, Arabian Sea, and Arabian Gulf. High densities and diversity of parrotfishes, and high rates of grazing (210%year−1) and erosion (1.57kgm−2year−1) characterised Red Sea reefs. Despite Arabian Sea and Red Sea reefs having broadly comparable abundances of parrotfishes, estimates of grazing (150%year−1) and erosion (0.43kgm−2year−1) were markedly lower in the Arabian Sea. Parrotfishes were extremely rare within the southern Arabian Gulf, and as such rates of grazing and erosion were negligible. This regional variation in abundance and functional composition of parrotfishes appears to be related to local environmental conditions.
اظهر المزيد [+] اقل [-]Monitoring of trace metals in coastal sediments around Korean Peninsula
2016
Hwang, Dong-Woon | Kim, Seong-Gil | Choi, Minkyu | Lee, In-Seok | Kim, Seong-Soo | Choi, Hee-Gu
Spatial distributions and temporal variations of trace metals in Korean coastal sediments were investigated by determining seven metals (As, Cd, Cr, Cu, Hg, Pb, and Zn) in sediment collected from 71 stations between 2004 and 2010 (n=491). High metal concentrations were found in the southeastern coast, where there are many cities and industrial complexes, indicating that metal concentrations in Korean coastal sediment are significantly influenced by human activities associated with urbanization and industrialization. However, metal concentrations in sediment did not markedly vary temporally, which was because the coast is managed sustainably and because of the characteristics of the sediment environments. Based on the sediment quality guidelines and geoaccumulation index, Korean coastal sediments are practically unpolluted with Cd, Cr, Cu, Hg, Pb and Zn but moderately polluted with As. More intensive monitoring is required to determine the potential As sources and to understand the As geochemical cycles in Korean coastal sediments.
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 [-]Integrated assessment of biomarker responses and microbiological analysis of oysters from São Luís Island, Brazil
2016
Ribeiro, E.B. | Bastos, L.S. | Galeno, L.S. | Mendes, R.S. | Garino, F. | Carvalho-Neta, R.N.F. | Costa, F.N.
This study was conducted to evaluate the use of biochemical biomarkers and microbiological analysis to identify levels of oyster contamination at different ports in São Luís Island (Maranhão), Brazil. Oysters were analyzed for total coliforms, thermotolerant coliforms, Escherichia coli and Aeromonas spp. In addition, tissue was removed from the digestive gland to determine the glutathione-S-transferase (GST) and catalase (CAT) activity. The highest percentage of microbiological contamination of oyster samples occurred during the rainy season. The activity of GST and catalase in oysters was also higher in the rainy season, coinciding with the greatest abundance of total and thermotolerant coliforms. Among the prospective biomarkers, GST showed the best results for identification of areas with higher levels of contamination.
اظهر المزيد [+] اقل [-]Bacterial inoculants for enhanced seed germination of Spartina densiflora: Implications for restoration of metal polluted areas
2016
Paredes-Páliz, Karina I. | Pajuelo, Eloísa | Doukkali, Bouchra | Caviedes, Miguel Ángel | Rodríguez-Llorente, Ignacio D. | Mateos-Naranjo, Enrique
The design of effective phytoremediation programs is severely hindered by poor seed germination on metal polluted soils. The possibility that inoculation with plant growth promoting rhizobacteria (PGPR) could help overcoming this problem is hypothesized. Our aim was investigating the role of PGPR in Spartina densiflora seed germination on sediments with different physicochemical characteristics and metal pollution degrees. Gram negative Pantoea agglomerans RSO6 and RSO7, and gram positive Bacillus aryabhattai RSO25, together with the consortium of the three strains, were used for independent inoculation experiments. The presence of metals (As, Cu, Pb and Zn) in sediments reduced seed germination by 80%. Inoculation with Bacillus aryabhattai RSO25 or Pantoea agglomerans RSO6 and RSO7 enhanced up to 2.5 fold the germination rate of S. densiflora in polluted sediments regarding non-inoculated controls. Moreover, the germination process was accelerated and the germination period was extended. The consortium did not achieve further improvements in seed germination.
اظهر المزيد [+] اقل [-]