Refinar búsqueda
Resultados 1511-1520 de 5,149
Structural and functional shifts of bacterioplanktonic communities associated with spatiotemporal gradients in river outlets of the subtropical Pearl River Estuary, South China Texto completo
2018
Mai, Yong-zhan | Lai, Zi-ni | Li, Xin-hui | Peng, Song-yao | Wang, Chao
In this study, we used high-throughput sequencing of 16S rRNA gene amplicons, to investigate the spatio-temporal variation in bacterial communities in surface-waters collected from eight major outlets of the Pearl River Estuary, South China. Betaproteobacteria were the most abundant class among the communities, followed by Gammaproteobacteria, Alphaproteobacteria, Actinobacteria, and Acidimicrobiia. Generally, alpha-diversity increased in winter communities and the taxonomic diversity of bacterial communities differed with seasonal and spatial differences. Temperature, conductivity, salinity, pH and nutrients were the crucial environmental factors associated with shifts in the bacterial community composition. Furthermore, inferred community functions that were associated with amino acid, carbohydrate and energy metabolisms were lower in winter, whereas the relative abundance of inferred functions associated with membrane transport, bacterial motility proteins, and xenobiotics biodegradation and metabolism, were enriched in winter. These results provide new insights into the dynamics of bacterial communities within estuarine ecosystems.
Mostrar más [+] Menos [-]Floating plastics in Adriatic waters (Mediterranean Sea): From the macro- to the micro-scale Texto completo
2018
Zeri, C. | Adamopoulou, A. | Bojanić Varezić, D. | Fortibuoni, T. | Kovač Viršek, M. | Kržan, A. | Mandic, M. | Mazziotti, C. | Palatinus, A. | Peterlin, M. | Prvan, M. | Ronchi, F. | Siljic, J. | Tutman, P. | Vlachogianni, Th
Macro- and microplastics abundances were determined in the Adriatic Sea following the MSFD TG10 protocol. The studied areas included populated gulfs, river outlets and offshore waters in five Adriatic countries. The use of small ships enabled us to detect small sized plastics (2.5–5 cm) and record average macroplastics densities of 251 ± 601 items km−2, one order of magnitude higher than previously considered. Results from manta net tows for microplastics revealed an average abundance of 315,009 ± 568,578 items km−2 (217 ± 575 g km−2). We found significantly higher microplastics abundances in nearshore (≤4 km) than in offshore waters (>4 km) and this trend seems to affect also the small sized macro plastic fragments (2.5–5 cm). The dominant polymers were polyethylene and polypropylene while the presence of some rare polymers and waxes used in food and dentistry indicated waste water treatment plants as potential sources of microplastics.
Mostrar más [+] Menos [-]Scleractinian coral microplastic ingestion: Potential calcification effects, size limits, and retention Texto completo
2018
Hankins, Cheryl | Duffy, Allyn | Drisco, Kathryn
The impact that microplastics (<5 mm) have on scleractinian coral is largely unknown. This study investigated calcification effects, size limits, and retention times of microbeads and microfibers in two Caribbean species, Montastraea cavernosa and Orbicella faveolata, in a series of three experiments. No calcification effects were seen in the two-day exposure to a microbead concentration of 30 mg L−1. M. cavernosa and O. faveolata actively ingested microbeads ranging in size from 425 μm–2.8 mm, however, a 212–250 μm size class did not elicit a feeding response. The majority of microbeads were expelled within 48 h of ingestion. There was no difference in ingestion or retention times of 425–500 μm microbeads versus 3–5 mm long microfibers. M. cavernosa and O. faveolata have the ability to recognize and reject indigestible material, yet, there is still a need to study effects of energetics and microplastic contamination as a result of ingestion and egestion.
Mostrar más [+] Menos [-]Pollutant bioaccumulation in the California spiny lobster (Panulirus interruptus) in San Diego Bay, California, and potential human health implications Texto completo
2018
Loflen, Chad L. | Buck, Travis | Bonnema, Autumn | Heim, Wesley A.
While the California spiny lobster (Panulirus interruptus) is an important commercial and recreational fishery species in California, there is a lack of data on bioaccumulation for the species. This study examined pollutant tissue concentrations in lobsters from San Diego Bay, California. Observed lobster pollutant tissue concentrations in tail muscle were compared to State of California pollutant advisory levels. Concentrations were then used to conduct risk assessment using catch data from the California Department of Fish and Wildlife.Study results found little bioaccumulation of organic pollutants in tail tissue, likely due to low observed lipids. Mercury was present, predominantly in methyl form, at concentrations above advisory levels. Recreational catch data for San Diego Bay showed increased non-cancer risk for fishers at the 90th percentile or greater of reported annual catch. Further studies should focus on non-tail tissues, as exploratory whole lobster samples (n = 2) showed elevated organic pollutants and metals.
Mostrar más [+] Menos [-]Microplastics in wastewater: State of the knowledge on sources, fate and solutions Texto completo
2018
Prata, Joana Correia
Microplastics are ubiquitous contaminants that could harm ecosystems. Wastewater contains microplastics and may lead to further contamination of the environment. This focus article presents a summary of current knowledge on microplastics in wastewater and possible solutions, suggesting current research needs.
Mostrar más [+] Menos [-]Abundance and distribution of benthic foraminifera as indicators of the quality of the sedimentary environment in a subtropical lagoon, Gulf of California Texto completo
2018
Gómez-León, Adriana | Rodríguez-Figueroa, Griselda M. | Shumilin, Evgueni | Carreño, Ana Luisa | Sánchez, Alberto
Abundance and spatial distribution of benthic foraminifera were used to evaluate the impacts of anthropogenic activities on sediment quality in a coastal lagoon in the Gulf of California. In 1985 and 2013, 27 samples of superficial sediments were collected. The foraminifera genera Ammonia, Cribroelphidium, Quinqueloculina and Peneroplis were dominant in both years. The abundance of Ammonia increased from 41% to 60%, while Peneroplis abundance decreased from a maximum of 50% in 1985 to 7% in 2013. The greater abundance of Ammonia and the greater spatial coverage of Ammonia and Cribroelphidium suggest a marked environmental deterioration in the quality of the sedimentary environment, which contrasts with studies of trace elements in the sediment of this lagoon. The Foram Stress Index indicates that sediment quality has deteriorated over time, likely due to the effects of anthropogenic activities around the lagoon.
Mostrar más [+] Menos [-]Marine animal forests as useful indicators of entanglement by marine litter Texto completo
2018
Galgani, François | Pham, Christopher K. | Claro, Francoise | Consoli, Pierpaolo
Marine animal forests as useful indicators of entanglement by marine litter Texto completo
2018
Galgani, François | Pham, Christopher K. | Claro, Francoise | Consoli, Pierpaolo
Entanglement of marine fauna is one of the principal impacts of marine litter, with an incidence that can vary strongly according to regions, the type and the quantity of marine litter. On the seafloor, areas dominated by sessile suspension feeders, such as tropical coral reefs or deep-sea coral and sponge aggregations, have been termed “animal forests” and have a strong potential to monitor the temporal and spatial trends of entanglement by marine litter, especially fishing gears. Several characteristics of these organisms represent advantages while avoiding constraints and bias. Biological constraints and logistical aspects, including tools, are discussed to better define a strategy for supporting long-term evaluation of accumulation and entanglement of marine litter.
Mostrar más [+] Menos [-]Marine animal forests as useful indicators of entanglement by marine litter Texto completo
2018
Galgani, Francois | Pham, Christopher K. | Claro, Francoise | Consoli, Pierpaolo
Entanglement of marine fauna is one of the principal impacts of marine litter, with an incidence that can vary strongly according to regions, the type and the quantity of marine litter. On the seafloor, areas dominated by sessile suspension feeders, such as tropical coral reefs or deep-sea coral and sponge aggregations, have been termed “animal forests” and have a strong potential to monitor the temporal and spatial trends of entanglement by marine litter, especially fishing gears. Several characteristics of these organisms represent advantages while avoiding constraints and bias. Biological constraints and logistical aspects, including tools, are discussed to better define a strategy for supporting long-term evaluation of accumulation and entanglement of marine litter.
Mostrar más [+] Menos [-]Microplastic in beach sediments of the Isle of Rügen (Baltic Sea) - Implementing a novel glass elutriation column Texto completo
2018
Hengstmann, Elena | Tamminga, Matthias | vom Bruch, Constantin | Fischer, Elke Kerstin
To extent the understanding on microplastics in the marine environment we performed a case study at four beaches on the Isle of Rügen considering abundance and spatial distribution of microplastics in beach sediments. For the analysis, density separation via a glass elutriation column was implemented. In advance, efficiencies were tested for two polymers, being not buoyant in water. Recovery rates of 80% for PET and 72% for PVC particles in sandy samples were achieved.A median abundance of 88.10 (Q1=55.01/Q3=114.72) microplastic particles per kg dry sediment or 2862.56 (Q1=1787.34/Q3=3727.28) particles per m2 was found at the beaches on Rügen. Fibers were more abundant than fragments at all beaches. In this study, no statistically significant differences but only tendencies were determined between the beaches with different exposition and anthropogenic activity as well as for distribution patterns which showed that microplastic fragments accumulate in topographic depressions, similar to macrolitter items.
Mostrar más [+] Menos [-]Synthetic microfibers in the marine environment: A review on their occurrence in seawater and sediments Texto completo
2018
Gago, J. | Carretero, O. | Filgueiras, A.V. | Viñas, L.
Synthetic microfibers in the marine environment: A review on their occurrence in seawater and sediments Texto completo
2018
Gago, J. | Carretero, O. | Filgueiras, A.V. | Viñas, L.
The objective of this review is to summarize information on microfibers in seawater and sediments from available scientific information.Microfibers were found in all reviewed documents. An heterogeneous approach is observed, with regard to sampling methodologies and units. Microfibers in sediments range from 1.4 to 40 items per 50mL or 13.15 to 39.48 items per 250g dry weight. In the case of water, microfibers values ranges from 0 to 450items·m⁻³ or from 503 to 459,681items·km⁻². Blue is the most common color in seawater and sediments, followed by transparent and black in the case of seawater, and black and colorful in sediments.Related with polymer type, polypropylene is the most common in water and sediments, followed by polyethylene in water and polyester in water and sediments. Some polymers were described only in water samples: high-density polyethylene, low-density polyethylene and cellophane, whilst only rayon was reported in sediments.
Mostrar más [+] Menos [-]Synthetic microfibers in the marine environment: A review on their occurrence in seawater and sediments Texto completo
2018
Gago, Jesús | Carretero-Perona, Olga | Filgueiras-Rodal, Ana Virginia | Viñas, Lucía
The objective of this review is to, summarize information on microfibers in seawater and sediments from available scientific information. Microfibers were found in all reviewed documents. An heterogeneous approach is observed, with regard to sampling methodologies and units. Microfibers in sediments range from 1.4 to 40 items per 50 mL or 13.15 to 39.48 items per 250 g dry weight. In the case of water, microfibers values ranges from 0 to 450 items.m(-3) or from 503 to 459,681 items.km(-2). Blue is the most common color in seawater and sediments, followed by transparent and black in the case of seawater, and black and colorful in sediments. Related with polymer type, polypropylene is the most common in water and sediments, followed by polyethylene in water and polyester in water and sediments. Some polymers were described only in water samples: high-density polyethylene, low-density polyethylene and cellophane, whilst only rayon was reported in sediments. | Peer reviewed
Mostrar más [+] Menos [-]Ammunition detection using high frequency multibeam snippet backscatter information Texto completo
2018
Kunde, Tina | Held, Philipp | Sternberg, Harald | Schneider von Deimling, Jens
The present study reports the evaluation of snippet backscatter information gathered with a high-frequency multibeam echosounder system (200–400 kHz) due to their usability to detect ammunition of different sizes in shallow coastal waters. Besides the feasibility of the snippet backscatter data, it was focused on the attainable horizontal accuracy in comparison to side-scan sonar and autonomous underwater vehicle (AUV) surveys. The data was collected in shallow coastal waters of up to 18 m water depth (Baltic Sea) close to an ammunition dumping site characterized by an almost flat seafloor covered with sand and silt sediments. The analysis of the multibeam compared to sidescan data indicates the snippet backscatter to be a promising prospective method for ammunition detection and being able to improve horizontal position accuracy of up to 0.08 m.
Mostrar más [+] Menos [-]