خيارات البحث
النتائج 1771 - 1780 من 4,938
Temporal and interspecific variation in feather mercury in four penguin species from Macquarie Island, Australia النص الكامل
2019
Gilmour, M.E. | Holmes, N.D. | Fleishman, A.B. | Kriwoken, L.K.
We measured mercury (Hg) concentrations in feathers from four penguin species collected on Macquarie Island, Southern Ocean, to 1) establish baseline Hg concentrations; and 2) compare Hg from samples collected in 2002 (“modern”) and from museum specimens collected between 1937 and 1976 (“historic”). Inter-specific differences in feather Hg reflected known differences in habitats and diversity of diets: benthic-foraging Gentoo penguins and Rockhopper penguins that foraged both inshore and offshore had significantly higher feather mercury than the more pelagic, specialist foraging King and Royal penguins. Hg significantly decreased between historic and modern samples in King and Royal penguins. This decrease could be due to changes in either diet, foodwebs, or atmospheric Hg input and sources in the Southern Hemisphere. Because Macquarie Island is home to 2.8 million marine animals, these data may indicate that other species that forage and breed in this region are also exposed to low Hg concentrations in this environment.
اظهر المزيد [+] اقل [-]A 120-year sedimentary record and its environmental implications, in a dated marine sediment core from Daya Bay in the northeastern South China Sea النص الكامل
2019
Zhou, Peng | Li, Dongmei | Zhao, Li | Li, Haitao | Ni, Zhixin | Zhao, Feng | Yu, Hansheng | Li, Xiaomin
In a Daya Bay 120-year dated sediment core(1892–2010), analyses were conducted of grain-size, water content, TOC, TIC, TC, loss on ignition, TN, BSi and TP, to reconstruct the anthropogenic activity history. The entire core was divided into four periods. Multi-parametric measurements, their ratios and interrelations are seen to clearly reflect the development of agriculture, aquaculture, industry and social economy surrounding Daya Bay. The trends of TOC, TOM and BSi after 1990 may be due to mass input of nutritious matter from aquaculture and industry, whereas the trends of BSi, TOC and TOM between 1960 and 1990 were owing to aquaculture and agriculture. Two peaks of BSi, TOC and TOM in 1994 and 2002 imply that the mass input of cooling water from nuclear power plants may be a significant contributor to ecological environment changes. Finally, some proposals were put forward for the healthy and sustainable development of Daya Bay.
اظهر المزيد [+] اقل [-]Microplastic content variation in water column: The observations employing a novel sampling tool in stratified Baltic Sea النص الكامل
2019
Zobkov, M.B. | Esiukova, E.E. | Zyubin, A.Y. | Samusev, I.G.
A new tool was developed for microplastics (MPs) investigation in the water column. It can collect several cubic meters of water from predefined water layers down to 100 m. The tool was tested in the Baltic Sea during the period of spring thermocline formation. Strong MPs stratification was observed at all of the sampled stations. On coastal stations (~30 m deep), stratification with high fibers content was associated with the proximity of terrestrial sources and estuarine discharges, while on off-shore stations the variability of MPs was related to vertical thermohaline structure. Mean MPs content was the 32.2 (SD 50.4) pcs/m³. Elevated MPs concentrations were observed in subsurface, near-bottom and thermohaline layers compared with intermediate layers. The heterogeneity of MPs distribution suggests that MPs particles can be retained above the density-gradient layers in coastal seas and the World Ocean.
اظهر المزيد [+] اقل [-]Inhabiting the technosphere: The encroachment of anthropogenic marine litter in Neotropical mangrove forests and its use as habitat by macrobenthic biota النص الكامل
2019
Riascos, José M. | Valencia, Natasha | Peña, Enrique J. | Cantera, Jaime R.
Coastal urbanization is leading to the accumulation of anthropogenic litter. Understanding the distribution and habitat use of litter by marine biota is important to predict how organisms will respond to anthropogenic changes. We assessed the density, distribution and composition of surface macro-litter (SML) in mangrove forests in Buenaventura (Colombia) and analysed how these microhabitats are used by marine biota. SML density ranged from 2 to 314 g m⁻² (0.22 to 35.5 items m⁻²), implying that mangrove forests surrounding Buenaventura city are among the most polluted coastal areas in the World. Biological assemblages colonizing SML differed according to position on the forest and litter type. The encroachment of SML in mangrove forest enables a seemingly transient colonization of resident and immigrant biota from intertidal rocky shores and subtidal hard bottoms. The successful colonization of SML poses questions regarding the potential for plastics or their leaching chemicals to transfer through food webs.
اظهر المزيد [+] اقل [-]Seawater quality criteria derivation and ecological risk assessment for oil pollution in China النص الكامل
2019
Zhenguang, Yan | Pan, Jinfen | Gao, Fu | An, Zhe | Liu, Huifang | Huang, Yi | Wang, Xiaobing
The establishment of water quality criteria (WQC) for oil pollutants is the basis for ecological risk assessment of marine oil pollution. Ecotoxicity data of oil pollutants to marine organisms in China were collected and toxicity test of oil to nine Chinese marine organisms were performed. Based on the WQC guidelines of the United States, the sea WQC of oil pollutants in China were studied. Then, the ecological risk of oil in 7 sea areas of China was assessed. Results showed that the long-term and short-term criteria of oil pollutants in China are 7.3 μg/L and 36 μg/L, respectively. Except for Qinhuangdao and Xiamen sea areas, the highest oil concentration in the other five sea areas exceeded the long-term WQC by >10 times, and the highest oil concentration in the Pearl River Estuary exceeded the long-term WQC by >100 times, indicating serious ecological risk.
اظهر المزيد [+] اقل [-]Stable isotopes and geochemical indicators in marine sediments as proxies for anthropogenic impact: A baseline for coastal environments of central Chile (33°S) النص الكامل
2019
Pastene, Marion | Quiroga, Eduardo | Hurtado, Carlos Felipe
Stable isotopes and geochemical proxies (TOC/TN and Chla/TOC) in sediments can be used to distinguish organic matter sources (anthropogenic, terrestrial, or marine). This study aims to characterize organic matter (OM) in superficial sediments from three sectors of central Chile (33°S) that are highly influenced by urban and industrial development. Our results show that a substantial fraction of these OM in Quintero Bay is anthropogenic, from industrial and domestic wastewater sources. In contrast, a mixture of terrestrial and anthropogenic OM dominates the isotopic signal of surface sediments from Concón, derived from non-point industrial and agriculture sources associated with the Aconcagua River basin, while Ritoque exhibited a mixture of different OM sources. However, deposition of allochthonous OM in our study area depends on coastal topography, which influences the local currents and well-ventilated waters, promoting the dispersion and assimilation of OM and thus providing an environment with a high capacity for natural remediation.
اظهر المزيد [+] اقل [-]Impact of pile-driving on Hector's dolphin in Lyttelton Harbour, New Zealand النص الكامل
2019
Leunissen, Eva M. | Rayment, William J. | Dawson, Stephen M.
Several dolphin species occur close inshore and in harbours, where underwater noise generated by pile-driving used in wharf construction may constitute an important impact. Such impacts are likely to be greatest on species such as the endangered Hector's dolphin (Cephalorhynchus hectori), which has small home ranges and uses this habitat type routinely. Using automated echolocation detectors in Lyttelton Harbour (New Zealand), we studied the distribution of Hector's dolphins using a gradient sampling design over 92 days within which pile-driving occurred on 46 days. During piling operations, dolphin positive minutes per day decreased at the detector closest to the piling but increased at the mid-harbour detector. Finer-grained analyses showed that close to the piling operation, detections decreased with increasing sound exposure level, that longer piling events were associated with longer reductions in detections, and that effects were long-lasting - detection rates took up to 83 h to return to pre-piling levels.
اظهر المزيد [+] اقل [-]Hg and δ15N in juvenile green turtles from southeastern Brazil (~23°S): Inferences about contamination levels and recruitment to coastal waters النص الكامل
2019
Di Beneditto, Ana Paula Madeira | Araújo, Beatriz Ferreira | Carvalho, Carlos Eduardo Veiga de
Total mercury (THg) and δ¹⁵N were analysed in liver and muscle of juvenile green turtles (Chelonia mydas) from a foraging site in southeastern Brazil (~23°S) to evaluate contamination levels and make inferences about the timescale that animals were recruited from oceanic to coastal waters. The values for THg and δ¹⁵N in liver and muscle were 432.2 and 72.8 μg kg⁻¹ and 10.0‰ and 9.2‰, respectively. THg concentrations in tissues indirectly indicated that the main food resources for this consumer (i.e., macroalgae) had negligible levels of this element. Thus, this foraging site could be considered a pristine area in terms of Hg contamination. The THg and δ¹⁵N in liver were derived by more recent food ingestion than those in muscle. The juvenile green turtles that died because of incidental captures in fisheries practiced along this foraging site were individuals newly recruited from oceanic waters.
اظهر المزيد [+] اقل [-]Macrozoobenthos in the Adriatic Sea ports: Soft-bottom communities with an overview of non-indigenous species النص الكامل
2019
Travizi, A. | Balković, I. | Bacci, T. | Bertasi, F. | Cuicchi, C. | Flander-Putrle, V. | Grati, F. | Grossi, L. | Jaklin, A. | Lipej, L. | Mavrič, B. | Mikac, B. | Marusso, V. | Montagnini, L. | Nerlović, V. | Penna, M. | Salvalaggio, V. | Santelli, A. | Scirocco, T. | Spagnolo, A. | Trabucco, B. | Vani, D.
The present paper is a contribution to the first initiative of the Port Baseline Survey (PBS) for Non-indigenous species (NIS) in the Mediterranean Sea. It presents a report on the soft-bottom macrobenthos from the five Adriatic ports: Bari, Ancona (Italy), Koper (Slovenia), Pula, Rijeka (Croatia), with a focus on the presence and contribution of NIS to native assemblages. Out of 451 species identified, only four were common to all ports. A total of eight NIS were recorded, five in surveyed ports and three in the lagoon connected to the Port of Koper. The highest number of NIS was recorded in Bari, and the highest abundance in Ancona and Bari. Generally, the number, abundance and contribution of NIS seems too low to cause a substantial impact on native communities in surveyed ports. The suitability of methods adopted for PBS for soft-bottom NIS was discussed and suggestion for methodological improvement is provided.
اظهر المزيد [+] اقل [-]CO2 leakage simulation: Effects of the decreasing pH to the survival and reproduction of two crustacean species النص الكامل
2019
Conradi, M. | Sánchez-Moyano, J.E. | Galotti, A. | Jiménez-Gómez, F. | Jiménez-Melero, R. | Guerrero, F. | Parra, G. | Bonnail, E. | DelValls, T.Á
The effects of CO2-related acidification on two crustacean populations, the isopod Cyathura carinata and the amphipod Elasmopus rapax, were studied. Three pH levels were tested: artificial seawater without CO2 injection and two levels of reduced pH. Even though RNA:DNA ratio was reduced for both species, no statistical significant differences were found between the control and the treatments. Both species experienced a reduction in survivorship, longevity and the body length of surviving animals; although the impairment observed in E. rapax was more severe than in C. carinata. The long life span isopod and the short life span amphipod experienced a high degree of impairment in the reproduction, likely due to the reallocation of resources from reproduction to body maintenance and increasing survival by postponing the brood production. Regardless of the underlying processes and the energetic pathways, both experienced failure to reproduce, which could lead to the local extinction of these species.
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