Affiner votre recherche
Résultats 1311-1320 de 4,044
Effects of Costa Concordia shipwreck on epiphytic assemblages and biotic features of Posidonia oceanica canopy Texte intégral
2016
Bacci, T. | Penna, M. | Rende, S.F. | Trabucco, B. | Gennaro, P. | Bertasi, F. | Marusso, V. | Grossi, L. | Cicero, A.M.
This research provides first information about Posidonia oceanica canopy in the area affected by Costa Concordia wreck. Percentage cover of algal and animal taxa on the leaves was estimated and biotic features of the meadow were measured in the period just after the shipwreck until its removal from the impacted site. Changes in epiphytic assemblages and some biotic features were detected in the Disturbed site compared with Control ones, highlighting effects due to the wreck presence and activities related to its removal. A temporary decrease of encrusting macroalgae and an increase of erected macroalgae and foraminifers, as well as a temporary increase of tip erosion of the canopy were detected in the Disturbed site. The obtained results were discussed and hypotheses about possible synergic effects occurred near the wreck were commented.
Afficher plus [+] Moins [-]A surface tension based method for measuring oil dispersant concentration in seawater Texte intégral
2016
Cai, Zhengqing | Gong, Yanyan | Liu, Wen | Fu, Jie | O'Reilly, S.E. | Hao, Xiaodi | Zhao, Dongye
This work developed a new method to determine concentration of Corexit EC9500A, and likely other oil dispersants, in seawater. Based on the principle that oil dispersants decrease surface tension, a linear correlation was established between the dispersant concentration and surface tension. Thus, the dispersant concentration can be determined by measuring surface tension. The method can accurately analyze Corexit EC9500A in the concentration range of 0.5–23.5mg/L. Minor changes in solution salinity (<0.3%), pH (7.9–9.0), and dissolved organic matter (<2.0mg/L as TOC) had negligible effects on the measurements. Moreover, effects of extracts from marine sediments were negligible, and thus, the method may be directly applied to seawater–sediment systems. The method accuracy was confirmed by comparing with direct TOC analysis. This simple, fast, economical method offers a convenient analytical tool for quantifying complex oil dispersants in water/seawater, which has been desired by the oil spill research community and industries.
Afficher plus [+] Moins [-]Study the symbiotic crude oil-degrading bacteria in the mussel Mactra stultorum collected from the Persian Gulf Texte intégral
2016
Bayat, Zeynab | Hassanshahian, Mehdi | Hesni, Majid Askari
Symbiotic associations are complex partnerships that can lead to new metabolic capabilities and the establishment of novel organisms. The diversity of these associations is very broad and there are still many mysteries about the origin and the exact relationship between the organisms that are involved in a symbiosis. The aim of the present study is to find symbiotic crude-oil degrading bacteria in the mussels that collected from the Persian Gulf. Fifteen crude-oil degrading bacteria were isolated from Mactra stultorum mussel that collected from oil contaminated area at Persian Gulf. According to high growth rate on crude oil five strains were selected from 15 isolated strains for more study. Determination of the nucleotide sequence of the gene encoding 16S rRNA show that these isolated strains belong to: Alcanivorax dieselolei strain BHA25, Idiomarina baltica strain BHA28, A. dieselolei strain BHA30, Alcanivorax sp. strain BHA32 and Vibrio azureus strain BHA36. Analysis of remaining of crude oil by Gas Chromatography (GC) confirmed that these strains can degrade: 64%, 63%, 71%, 58% and 75% of crude oil respectively.
Afficher plus [+] Moins [-]Persistent organic pollutants and polycyclic aromatic hydrocarbons in penguins of the genus Pygoscelis in Admiralty Bay — An Antarctic specially managed area Texte intégral
2016
Montone, Rosalinda C. | Taniguchi, Satie | Colabuono, Fernanda I. | Martins, César C. | Cipro, Caio Vinícius Z. | Barroso, Hileia S. | da Silva, Josilene | Bícego, Márcia C. | Weber, Rolf R.
Persistent organic pollutants were assessed in fat samples of the Gentoo (Pygoscelis papua), Chinstrap (Pygoscelis antarcticus) and Adélie (Pygoscelis adeliae) penguins collected during the austral summers of 2005/06 and 2006/07 in Admiralty Bay, King George Island, Antarctica. The predominant organic pollutants were PCB (114 to 1115), polycyclic aromatic hydrocarbons (PAHs) (60.1 to 238.7), HCB (<0.3 to 132.2) and BDE-47 (<1.0 to 10.7) in ng g−1 wet weight. The mean concentrations of the majority of organic pollutants were similar among the three species of penguins. Chicks of all three species showed similar profiles of PCB congeners, with predominance of lower chlorinated compounds. The distribution of PAHs was similar in all birds, with a predominance of naphthalene and alkyl-naphthalene, which are the main constituents of arctic diesel fuel. These data contribute to the monitoring of the continued exposure to organic pollutants in the Antarctic biota.
Afficher plus [+] Moins [-]Impact of metal pollution on shrimp Crangon affinis by NMR-based metabolomics Texte intégral
2016
Ji, Chenglong | Yu, Deliang | Wang, Qing | Li, Fei | Zhao, Jianmin | Wu, Huifeng
Both cadmium and arsenic are the important metal/metalloid pollutants in the Bohai Sea. In this work, we sampled the dominant species, shrimp Crangon affinis, from three sites, the Middle of the Bohai Sea (MBS), the Yellow River Estuary (YRE) and the Laizhou Bay (LZB) along the Bohai Sea. The concentrations of metals/metalloids in shrimps C. affinis indicated that the YRE site was polluted by Cd and Pb, while the LZB site was contaminated by As. The metabolic differences between shrimps C. affinis from the reference site (MBS) and metal-pollution sites (YRE and LZB) were characterized using NMR-based metabolomics. Results indicated that the metal pollutions in YRE and LZB induced disturbances in osmotic regulation and energy metabolism via different metabolic pathways. In addition, a combination of alanine and arginine might be the biomarker of Cd contamination, while BCAAs and tyrosine could be the biomarkers of arsenic contamination in C. affinis.
Afficher plus [+] Moins [-]Synergistic effect of elevated temperature, pCO2 and nutrients on marine biofilm Texte intégral
2016
Baragi, Lalita V. | Anil, Arga Chandrashekar
Natural marine biofilms provide signatures of the events that occur over a period of time and can be used as bioindicators of environmental changes. Hence, the effects of temperature (30 and 34°C), pCO2 (400 and 1500μatm) and nutrients (unenriched and enriched f/2 media) on the marine biofilm were evaluated using a 2×2×2 factorial design. In unenriched condition, acidification significantly increased the abundance of phytoperiphytes whereas reduced that of bacteria and it was vice versa in the enriched condition. Warming had significant negative effect on the abundance of both phytoperiphytes and bacteria, except in unenriched condition wherein it favoured bacterial growth. Synergistically, acidification and warming had deleterious effects resulting in further reduction in the abundance of both phytoperiphytes and bacteria, except in enriched condition wherein bacterial abundance increased. Such changes in biofilm communities in response to warming and acidification can have cascading effect on the subsequent build-up of macrofouling community.
Afficher plus [+] Moins [-]Comparison of wastewater-associated contaminants in the bed sediment of Hempstead Bay, New York, before and after Hurricane Sandy Texte intégral
2016
Fisher, Shawn C. | Phillips, Patrick J. | Brownawell, Bruce J. | Browne, James P.
Changes in bed sediment chemistry of Hempstead Bay (HB) have been evaluated in the wake of Hurricane Sandy, which resulted in the release of billions of liters of poorly-treated sewage into tributaries and channels throughout the bay. Surficial grab samples (top 5cm) collected before and (or) after Hurricane Sandy from sixteen sites in HB were analyzed for 74 wastewater tracers and steroid hormones, and total organic carbon. Data from pre- and post-storm comparisons of the most frequently detected wastewater tracers and ratios of steroid hormone and of polycyclic aromatic hydrocarbon concentrations indicate an increased sewage signal near outfalls and downstream of where raw sewage was discharged. Median concentration of wastewater tracers decreased after the storm at sites further from outfalls. Overall, changes in sediment quality probably resulted from a combination of additional sewage inputs, sediment redistribution, and stormwater runoff in the days to weeks following Hurricane Sandy.
Afficher plus [+] Moins [-]Selective responses of benthic foraminifera to thermal pollution Texte intégral
2016
Titelboim, Danna | Almogi-Labin, Ahuva | Herut, Barak | Kucera, M. (Michal) | Schmidt, Christiane | Hyams-Kaphzan, Orit | Ovadia, Ofer | Abramovich, Sigal
Persistent thermohaline pollution at a site along the northern coast of Israel, due to power and desalination plants, is used as a natural laboratory to evaluate the effects of rising temperature and salinity levels on benthic foraminifera living in shallow hard-bottom habitats. Biomonitoring of the disturbed area and a control station shows that elevated temperature is a more significant stressor compared to salinity, thus causing a decrease in abundance and richness.Critical temperature thresholds were observed at 30 and 35°C, the latter representing the most thermally tolerant species in the studied area Pararotalia calcariformata, which is the only symbiont-bearing species observed within the core of the heated area.Common species of the shallow hard-bottom habitats including several Lessepsian invaders are almost absent in the most exposed site indicating that excess warming will likely impede the survival of these species that currently benefit from the ongoing warming of the Eastern Mediterranean.
Afficher plus [+] Moins [-]Potential ecological risk of heavy metal contamination in sediments and macrobenthos in coastal wetlands induced by freshwater releases: A case study in the Yellow River Delta, China Texte intégral
2016
Li, Ming | Yang, Wei | Sun, Tao | Jin, Yuwan
We investigated the nine heavy metal contents in the sediments and macrobenthos of the Yellow River Delta Wetlands using three experimental areas that received freshwater releases and one reference area that did not. Heavy metal contents, the single-factor contamination index (SFCI), the metal contamination index (MCI), and the biota-sediment accumulation factor (BSAF) were used to evaluate the potential ecological risk and bioaccumulation. We found that As exceeded the national standard value by more than 50%, and that the ranges of SFCI for each metal were generally larger in autumn than in spring. MCI showed no clear pattern, but the BSAF results suggest that Cd bioaccumulates from sediments to macrobenthos. Pollution-resistant species such as Corophium sinense, Chironomus sp., and Einfeldia sp. became dominant in the areas receiving freshwater releases, and provide direct evidence of ecological risk in the wetlands. Our results provide preliminary information to guide managers for ecological risk assessments.
Afficher plus [+] Moins [-]Productivity and sea surface temperature are correlated with the pelagic larval duration of damselfishes in the Red Sea Texte intégral
2016
Robitzch, Vanessa S.N. | Lozano-Cortés, Diego | Kandler, Nora M. | Salas, Eva | Berumen, Michael L.
We examined the variation of pelagic larval durations (PLDs) among three damselfishes, Dascyllus aruanus, D. marginatus, and D. trimaculatus, which live under the influence of an environmental gradient in the Red Sea. PLDs were significantly correlated with latitude, sea surface temperature (SST), and primary production (CHLA; chlorophyll a concentrations). We find a consistent decrease in PLDs with increasing SST and primary production (CHLA) towards the southern Red Sea among all species. This trend is likely related to higher food availability and increased metabolic rates in that region. We suggest that food availability is a potentially stronger driver of variation in PLD than temperature, especially in highly oligotrophic regions. Additionally, variations in PLDs were particularly high among specimens of D. marginatus, suggesting a stronger response to local environmental differences for endemic species. We also report the first average PLD for this species over a broad geographic range (19.82±2.92days).
Afficher plus [+] Moins [-]