خيارات البحث
النتائج 731 - 740 من 1,310
Accumulation of butyltin compounds in cetaceans from Korean coastal waters النص الكامل
2011
Choi, Minkyu | Moon, Hyo-Bang | An, Yong-Rock | Choi, Seok-Gwan | Choi, Hee-Gu
Data on the occurrence and accumulation profiles of butyltins (BTs), including tributyltin (TBT), in marine mammals are scarce. This is the first study to investigate residue levels and accumulation patterns of BTs in cetaceans from Korean coastal waters. The total concentrations of BTs (sum of mono- to tri-butyltins) in minke whales (Balaenoptera acutorostrata) and long-beaked common dolphins (Delphinus capensis) ranged from 15.7 to 297ng/g wet weight (mean: 100ng/g wet weight) and from 59.0 to 412ng/g wet weight (mean: 228ng/g wet weight), respectively. Dibutyltin (DBT) accounted for 63% of the total BTs in all cetacean samples. Significant species-specific differences in BT concentrations, possibly due to the differences in their habitat and diet, were found between the two cetacean species. The concentrations of DBT and TBT in most cetacean samples exceeded the threshold value for cytotoxic effects in cetaceans, implying potentially adverse health risks from exposure to BTs.
اظهر المزيد [+] اقل [-]Metal distribution in sediment cores from São Paulo State Coast, Brazil النص الكامل
2011
Silva, Paulo S.C. | Damatto, Sandra R. | Maldonado, Caio | Fávaro, Deboráh I.T. | Mazzilli, Barbara P.
Ten sediment core samples with lengths ranging from 35 to 100cm were collected in the Baixada Santista region and analyzed to determine As, Br, Co, Cr, Cs, Fe, Rb, Sb, Ta, Th, U, Zn and rare earths (Sc, Ce, Eu, La, Lu, Nd, Sm, Tb and Yb) level concentrations using instrumental neutron activation analysis (INAA). The studied region is located in the southeastern coast of São Paulo State and is comprised of a densely urbanized area, the largest industrial complex of the country, with a predominance of petrochemical and fertilizer plants. It is also home to Brazil’s most important and busiest port. The conclusions found that the As, La, Sm, Ne, Ce, Eu, Hf, Ta, Th, and U elements have a high background level in the region and that Fe and Zn were the main indicators of anthropogenic contribution in the sediments.
اظهر المزيد [+] اقل [-]Macrobenthos habitat mapping in a tidal flat using remotely sensed data and a GIS-based probabilistic model النص الكامل
2011
Choi, Jong-Kuk | Oh, Hyun-Joo | Koo, Bon Joo | Lee, Saro | Ryu, Joo-Hyung
This paper proposes and tests a method of producing macrofauna habitat potential maps based on a weights-of-evidence model (a probabilistic approach) for the Hwangdo tidal flat, Korea. Samples of macrobenthos were collected during field work, and we considered five mollusca species for habitat mapping. A weights-of-evidence model was used to calculate the relative weights of 10 control factors that affect the macrobenthos habitat. The control factors were compiled as a spatial database from remotely sensed data combined with GIS analysis. The relative weight of each factor was integrated as a species potential index (SPI), which produced habitat potential maps. The maps were compared with the surveyed habitat locations, revealing a strong correlation between the potential maps and species locations. The combination of a GIS-based weights-of-evidence model and remote sensing techniques is an effective method in determining areas of macrobenthos habitat potential in a tidal flat setting.
اظهر المزيد [+] اقل [-]Is the cutting of oil contaminated marshes an efficient clean-up technique in a subtropical estuary? النص الكامل
2011
Wolinski, André L.T.O. | Lana, Paulo C. | Sandrini-Neto, Leonardo
Cutting and removal of oil-impacted marsh plants are still used worldwide as a clean-up and recovery technique. To experimentally test the efficacy of cutting and removing marsh plants under subtropical conditions, we simulated an oil spill (Bunker MF-180) in Spartina alterniflora marshes and compared the responses of plant height, biomass, density of culms and number of flowering plants in high and low energy areas in Paranaguá Bay (S Brazil) for about 9months. Cutting and removal were inefficient in promoting or accelerating the recovery of the impacted areas. Cut or uncut impacted marshes fully recovered within 6months, both in low and high energy areas. Plant cutting should be practiced only when there is an effective risk of contamination of groundwater near urban areas, when obvious aesthetical issues are involved in areas of touristic interest or when there are real short-term conservation risks to threatened species.
اظهر المزيد [+] اقل [-]Some challenges of an “upside down” nitrogen budget – Science and management in Greenwich Bay, RI (USA) النص الكامل
2011
DiMilla, Peter A. | Nixon, Scott W. | Oczkowski, Autumn J. | Altabet, Mark A. | McKinney, Richard A.
When nutrients impact estuarine water quality, scientists and managers instinctively focus on quantifying and controlling land-based sources. However, in Greenwich Bay, RI, the estuary opens onto a larger and more intensively fertilized coastal water body (Narragansett Bay). Previous inventories of nitrogen (N) inputs to Greenwich Bay found that N inputs from Narragansett Bay exceeded those from the local watershed, suggesting that recent efforts to reduce local watershed N loads may have little effect on estuarine water quality. We used stable isotopes of N to characterize watershed and Narragansett Bay N sources as well as the composition of primary producers and consumers throughout Greenwich Bay. Results were consistent with previous assessments of the importance of N inputs to Greenwich Bay from Narragansett Bay. As multiple N sources contribute to estuarine water quality, effective management requires attention to individual sources commensurate with overall magnitude, regardless of the political complications that may entail.
اظهر المزيد [+] اقل [-]Antifouling strategies: History and regulation, ecological impacts and mitigation النص الكامل
2011
Dafforn, Katherine A. | Lewis, John A. | Johnston, Emma L.
Biofouling increases drag on marine vessels resulting in higher fuel consumption and can also facilitate the transport of harmful non-indigenous species (NIS). Antifouling technologies incorporating biocides (e.g., copper and tributyltin) have been developed to prevent settlement of organisms on vessels, but their widespread use has introduced high levels of contamination into the environment and raised concerns about their toxic effects on marine communities. The recent global ban on tributyltin (1 January 2008) and increasing regulation of copper have prompted research and development of non-toxic paints. This review synthesises existing information regarding the ecological impact of biocides in a wide range of organisms and highlights directions for the management of antifouling paints. We focus particularly on representatives of the recent past (copper and tributyltin) and present (copper and ‘booster’) biocides. We identify knowledge gaps in antifouling research and provide recommendations relating to the regulation and phasing-out of copper.
اظهر المزيد [+] اقل [-]Do long lived seabirds reduce the negative effects of acute pollution on adult survival by skipping breeding? A study with European storm petrels (Hydrobates pelagicus) during the “Prestige” oil-spill النص الكامل
2011
Zabala, Jabi | Zuberogoitia, Iñigo | Martínez-Climent, Jose Antonio | Etxezarreta, Jon
We estimated the survival probability of breeding European storm petrels before, during and after a severe oil-spill. We hypothesized that petrels might have deserted the breeding colony to maximize their own survival probability and we expected no major change on adult survival probabilities as a consequence of the spill. We used an information-theoretical approach and multi-model inference to assess the strength of the evidence in favour of different hypotheses. Evidence contained in the data clearly supported the non-effect of the spill on adult survival hypothesis while punctual impact of the spill on survival and expanded (3years) impact alternatives received less support. The effect size of the spill on averaged survival estimates was negligible in every case. We suggest that petrels minimized the impact of acute pollution by not investing in reproduction. We suggest that short-medium term management actions after oil-spills and similar catastrophes should focus on ecosystem restoration.
اظهر المزيد [+] اقل [-]Contrasting time trends of organic contaminants in Antarctic pelagic and benthic food webs النص الكامل
2011
Brink, Nico W. van den | Riddle, Martin J. | van den Heuvel-Greve, Martine | van Franeker, Jan Andries
We demonstrate that pelagic Antarctic seabirds show significant decreases in concentrations of some persistent organic pollutants. Trends in Adélie penguins and Southern fulmars fit in a general pattern revealed by a broad literature review. Downward trends are also visible in pelagic fish, contrasting sharply with steady or increasing concentrations in Antarctic benthic organisms. Transfer of contaminants between Antarctic pelagic and benthic food webs is associated with seasonal sea-ice dynamics which may influence the balance between the final receptors of contaminants under different climatic conditions. This complicates the predictability of future trends of emerging compounds in the Antarctic ecosystem, such as of the brominated compounds that we detected in Antarctic petrels. The discrepancy in trends between pelagic and benthic organisms shows that Antarctic biota are still final receptors of globally released organic contaminants and it remains questionable whether the total environmental burden of contaminants in the Antarctic ecosystem is declining.
اظهر المزيد [+] اقل [-]Risk mapping for sensitive species to underwater anthropogenic sound emissions: Model development and validation in two Mediterranean areas النص الكامل
2011
Azzellino, A. | Lanfredi, C. | D’Amico, A. | Pavan, G. | Podestà, M. | Haun, J.
Recent observations of cetacean mass strandings, coincident with anthropogenic sounds emissions, have raised concerns on the potential environmental impact of underwater noise. Cuvier’s beaked whale (Ziphius cavirostris) was reported in all the cited stranding events. Within the NATO Marine Mammal Risk Mitigation project (MMRM), multiple interdisciplinary sea trials have been conducted in the Mediterranean Sea with the objective of developing tools and procedures to mitigate the impact of underwater sound emissions. During these cruises, visual observations, passive acoustic detections and environmental data were collected. The aim of this study was to evaluate “a priori” predictions of Cuvier’s beaked whale presence in the Alboran Sea, using models developed in the Ligurian Sea that employ bathymetric and chlorophyll features as predictors. The accuracy of these predictions was found adequate and elements are given to account for the uncertainties associated to the use of models developed in areas different from their calibration site.
اظهر المزيد [+] اقل [-]Seabirds and chronic oil pollution: Self-cleaning properties of gulls, Laridae, as revealed from colour-ring sightings النص الكامل
2011
(C.J.) Camphuysen, Kees
Mystery oil spills off the Dutch coast affected colonial, adult Lesser Black-backed Gulls prior to and within the breeding season. From colour-ringed individuals, it was demonstrated that most oiled birds survived and were clean within a few weeks and often bred successfully. Further evidence of self-cleaning properties of Larus-gulls is provided from a long-term colour-ringing project (1984–2009). In total 46 birds were reported ‘oiled’, two died, but the majority cleaned itself and survived for up to 20years after being oiled. From colour-ring data and 30years of beached bird surveys (1980–2010) it is demonstrated that the effects of chronic oil pollution is larger in winter than in summer; a reflection of seasonal differences in exposure and environmental conditions. The self-cleaning properties of gulls are such that long-term survival is not necessarily jeopardised and even in a breeding season, not all is lost in case of a spill.
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