خيارات البحث
النتائج 731 - 740 من 3,243
Exposures of zebrafish through diet to three environmentally relevant mixtures of PAHs produce behavioral disruptions in unexposed F1 and F2 descendant
2015
Vignet, Caroline | Joassard, Lucette | Lyphout, Laura | Guionnet, Tiphaine | Goubeau, Manon | Le Menach, Karyn | Brion, Francois | Kah, Olivier | Chung, Bon-chu | Budzinski, Helene | Begout, Marie-laure | Cousin, Xavier
The release of polycyclic aromatic hydrocarbons (PAHs) into the environment has increased very substantially over the last decades. PAHs are hydrophobic molecules which can accumulate in high concentrations in sediments acting then as major secondary sources. Fish contamination can occur through contact or residence nearby sediments or though dietary exposure. In this study, we analyzed certain physiological traits in unexposed fish (F1) issued from parents (F0) exposed through diet to three PAH mixtures at similar and environmentally relevant concentrations but differing in their compositions. For each mixture, no morphological differences were observed between concentrations. An increase in locomotor activity was observed in larvae issued from fish exposed to the highest concentration of a pyrolytic (PY) mixture. On the contrary, a decrease in locomotor activity was observed in larvae issued from heavy oil mixture (HO). In the case of the third mixture, light oil (LO), a reduction of the diurnal activity was observed during the setup of larval activity. Behavioral disruptions persisted in F1-PY juveniles and in their offspring (F2). Endocrine disruption was analyzed using cyp19a1b:GFP transgenic line and revealed disruptions in PY and LO offspring. Since no PAH metabolites were dosed in larvae, these findings suggest possible underlying mechanisms such as altered parental signaling molecule and/or hormone transferred in the gametes, eventually leading to early imprinting. Taken together, these results indicate that physiological disruptions are observed in offspring of fish exposed to PAH mixtures through diet.
اظهر المزيد [+] اقل [-]An evaluation of surface micro- and mesoplastic pollution in pelagic ecosystems of the Western Mediterranean Sea
2015
Faur, Florian | Saini, Camille | Potter, Gael | Galgani, Francois | De Alencastro, Luiz Felippe | Hagmann, Pascal
This study examines the distribution, abundance and characteristics of surface micro- and mesoplastic debris in the Western Mediterranean Sea. 41 samples were collected in 2011 (summer) and 2012 (summer). Results, firstly, revealed that micro- (<5mm) and mesoplastic debris were widely and uniformly distributed in this area with average concentrations of 130,000 parts/km(2) and 5700 parts/km(2), respectively. Importantly, a strong correlation between micro- and mesoplastic concentrations was identified. Secondly, a classification based on the shape and appearance of microplastics indicated the predominant presence of fragments (73 %) followed by thin films (14 %). Thirdly, the average mass ratio of microplastic to dry organic matter has been measured at 0.5, revealing a significant presence of microplastics in comparison to plankton. Finally, a correction method was applied in order to correct wind mixing effect on microplastics' vertical distribution. This data allows for a comprehensive view, for the first time, of the spatial distribution and nature of plastic debris in the Western Mediterranean Sea.
اظهر المزيد [+] اقل [-]Informing Marine Spatial Planning (MSP) with numerical modelling: A case-study on shellfish aquaculture in Malpeque Bay (Eastern Canada)
2015
Filgueira, Ramon | Guyondet, Thomas | Bacher, Cedric | 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 [-]Parameter optimization method for the water quality dynamic model based on data-driven theory
2015
Liang, Shuxiu | Han, Songlin | Sun, Zhaochen
Parameter optimization is important for developing a water quality dynamic model. In this study, we applied data-driven method to select and optimize parameters for a complex three-dimensional water quality model. First, a data-driven model was developed to train the response relationship between phytoplankton and environmental factors based on the measured data. Second, an eight-variable water quality dynamic model was established and coupled to a physical model. Parameter sensitivity analysis was investigated by changing parameter values individually in an assigned range. The above results served as guidelines for the control parameter selection and the simulated result verification. Finally, using the data-driven model to approximate the computational water quality model, we employed the Particle Swarm Optimization (PSO) algorithm to optimize the control parameters. The optimization routines and results were analyzed and discussed based on the establishment of the water quality model in Xiangshan Bay (XSB).
اظهر المزيد [+] اقل [-]Exceptionally high Cd levels and other trace elements in eggshells of American oystercatcher (Haematopus palliatus) from the Bahía Blanca Estuary, Argentina
2015
Simonetti, Pía | Botté, Sandra Elizabeth | Marcovecchio, Jorge Eduardo
Concentrations of six trace metals were determined in the eggshells of American oystercatchers (Haematopus palliatus) from the Bahía Blanca estuary, Argentina. All metals measured in selected samples presented concentrations above the detection limit. Means found for Cu, Pb, Cr, Zn and Ni were as follow: 2.02±0.52, 7.23±2.33, 0.78±0.03, 2.22±1.13 and 6.05±0.89mg/kg dw. The mean concentrations of Cd found were surprisingly high: 13.28±3.38mg/kg dw. Previous studies made on prey items of the American oystercatchers showed low to medium concentrations of the six trace metals. This may indicate a possible transfer of the metals that are available in the environment through food chains. Our study indicates that American oystercatchers sequester heavy metals in their eggshells. Therefore the eggshells may be useful as biomonitors for trace metal contamination in the Bahía Blanca estuary.
اظهر المزيد [+] اقل [-]Multivariate and geo-spatial approach for seawater quality of Chidiyatappu Bay, south Andaman Islands, India
2015
Jha, Dilip Kumar | Vinithkumar, Nambali Valsalan | Sahu, Biraja Kumar | Dheenan, Palaiya Sukumaran | Das, Apurba Kumar | Begum, Mehmuna | Devi, Marimuthu Prashanthi | Kirubagaran, Ramalingam
Chidiyatappu Bay is one of the least disturbed marine environments of Andaman & Nicobar Islands, the union territory of India. Oceanic flushing from southeast and northwest direction is prevalent in this bay. Further, anthropogenic activity is minimal in the adjoining environment. Considering the pristine nature of this bay, seawater samples collected from 12 sampling stations covering three seasons were analyzed. Principal Component Analysis (PCA) revealed 69.9% of total variance and exhibited strong factor loading for nitrite, chlorophyll a and phaeophytin. In addition, analysis of variance (ANOVA-one way), regression analysis, box-whisker plots and Geographical Information System based hot spot analysis further simplified and supported multivariate results. The results obtained are important to establish reference conditions for comparative study with other similar ecosystems in the region.
اظهر المزيد [+] اقل [-]Anthropogenic impacts on meiobenthic Ostracoda (Crustacea) in the moderately polluted Kasado Bay, Seto Inland Sea, Japan, over the past 70 years
2015
Irizuki, Toshiaki | Ito, Hisayo | Sako, Megumi | Yoshioka, Kaoru | Kawano, Shigenori | Nomura, Ritsuo | Tanaka, Yuichiro
Two sediment cores were obtained from Kasado Bay, a moderate-polluted enclosed bay in Japan, to examine anthropogenic impacts on Ostracoda over the past ca. 70years. We analyzed ostracode abundance and diversity, grain size, and CHN, and used 210Pb and 137Cs as the dating method. The present study showed that cross-plot comparisons of ostracode abundance and each environmental factor, based on sediment core data, could be used to identify ostracode species as indicators for anthropogenic influences. Ostracode abundance reflected mainly the changes that had occurred in total organic carbon content in sediments related to eutrophication, but heavy metal concentration did not directly influence several ostracode abundance in the bay. Environmental deterioration because of eutrophication started in the 1960s. The regulations regarding the chemical oxygen demand in waters introduced in the 1980s probably influence ostracode abundance for certain species in this period. Currently, Kasado Bay is not experiencing severe degradation.
اظهر المزيد [+] اقل [-]Antifouling assessments on biogenic nanoparticles: A field study from polluted offshore platform
2015
Krishnan, Muthukumar | Sivanandham, Vignesh | Hans-Uwe, Dahms | Murugaiah, Santhosh Gokul | Seeni, Palanichamy | Gopalan, Subramanian | Rathinam, Arthur James
Turbinaria ornata mediated silver nanoparticles (TOAg-NPs) were evaluated for antibacterial activity against 15 biofilm forming bacterial isolates. A field study in natural seawater for 60days showed antifouling activity of TOAg-NPs on stainless steel coupons (SS-304) coated with Apcomin zinc chrome (AZC) primer. Though TOAg-NPs showed broad spectrum of antibacterial activity, the maximum zone of inhibition was with Escherichia coli (71.9%) and a minimum with Micrococcus sp. (40%) due to the EPS secretion from Gram-positive bacteria. Compared to control coupons (18.9 [×103], 67.0 [×103], 13.5 [×104] and 24.7 [×104]CFU/cm2), experimental biocide coupons (71.0 [×102], 32.0 [×103], 82.0 [×103] and 11.3 [×104]CFU/cm2) displayed lesser bacterial population density. Toxicity studies revealed 100% mortality for Balanus amphitrite larvae at 250μgml−1 concentration within 24h, while 56.6% recorded for Artemia marina at the same concentration indicating less toxicity to non target species. It proved that AZC+TOAg-NPs prevent biofouling by its Ag-NS affinity and antimicrobial effectivity.
اظهر المزيد [+] اقل [-]A case study on effects of oil spills and tar-ball pollution on beaches of Goa (India)
2015
Rekadwad, Bhagwan N | Khobragade, Chandrahasya N
This paper reports the impact of oil spills and tar-ball pollution on the coastal ecosystem of Goa. The factors responsible for degrading the marine ecosystem of the Goan coastline are analyzed. Uncontrolled activities were found to degrade the marine and coastal biodiversity, in turn polluting all beaches. This had a direct impact on the Goan economy through a decline in tourism. The government must adopt the necessary control measures to restore Goan beaches and the surrounding coastal areas.
اظهر المزيد [+] اقل [-]Congruency analysis of biofilm-dwelling ciliates as a surrogate of eukaryotic microperiphyton for marine bioassessment
2015
Xu, Guangjian | Wang, Zheng | Yang, Zhongwen | Xu, Henglong
Biofilm-dwelling ciliates are primary components of the eukaryotic microperiphyton in both species composition and community structure. To evaluate the congruency of biofilm-dwelling ciliates as potential surrogates of the eukaryotic microperiphyton, a dataset was collected every month at four stations from the coastal waters of the Yellow Sea, northern China, and assessed. Sufficient species abundance data were obtained for ciliated protozoans at high taxonomic levels up to the family level, indicating a significant variation along the gradient of contamination. Correlation analyses revealed that the taxa richness of these matrices can explain >85% of the variance in that of the full species dataset. The cost/benefit analysis showed that the protozoan subset at low resolutions up to the family level may be used as a potential surrogate of the original dataset. Thus, we suggest that the protozoan assemblages at genus- and/or family-level resolutions may be useful, cost-efficient surrogates of the original dataset for bioassessment in marine ecosystems.
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