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Resultados 1701-1710 de 4,936
Occurrence and identification of microplastics along a beach in the Biosphere Reserve of Lanzarote Texto completo
2019
Edo, Carlos | Tamayo-Belda, Miguel | Martínez-Campos, Sergio | Martín-Betancor, Keila | González-Pleiter, Miguel | Pulido-Reyes, Gerardo | García-Ruiz, Carmen | Zapata, Félix | Leganés, Francisco | Fernández-Piñas, Francisca | Rossal S., J. Roberto (Julio Roberto Rossal Salazar)
This work studied the accumulation of plastic debris in a remote beach located in La Graciosa island (Chinijo archipelago, Canary Islands). Microplastics were sampled in the 1–5 mm mesh opening range. An average plastic density of 36.3 g/m2 was obtained with a large variability along the 90 m of the beach (from 8.5 g/m2 to 103.4 g/m2). Microplastic particles preferentially accumulated in the part of the beach protected by rocks. A total number of 9149 plastic particles were collected, recorded and measured, 87% of which corresponded to fragments. Clear colours and microscopic evidence of weathering corresponded to aged plastics wind-driven by the surface Canary Current. The chemical composition of plastics particles corresponded to PE (63%), PP (32%) and PS (3%). Higher PE/PP ratios were recorded in the more protected parts of the beach, suggesting preferential accumulation of more aged fragments.
Mostrar más [+] Menos [-]Differential bleaching and recovery pattern of southeast Indian coral reef to 2016 global mass bleaching event: Occurrence of stress-tolerant symbiont Durusdinium (Clade D) in corals of Palk Bay Texto completo
2019
Thinesh, T. | Meenatchi, R. | Jose, Polpass Arul | Kiran, G Seghal | Selvin, Joseph
Information about coral community response to bleaching on Indian reefs is much more limited compared with Indo-Pacific reefs, with no understanding of algal symbionts. We investigated a reef in Palk Bay to understand the coral community response to 2016 bleaching event and to reveal dominant symbiont type association in four common coral genera. Out of 508 colonies surveyed, we found 20.9% (106) mortality in 53.8% (n = 290) of bleached corals. We found differential bleaching and recovery pattern among coral genera. Bleaching was most prevalent in Acropora (86.36%), followed by Porites (65.45%), while moderate to no bleaching was recorded in Favites 5.88%, Symphyllia 51.11% and Favia 55.77%, Platygyra 41.67%, Goniastrea 41.83%. Pre-bleaching and post bleaching samplings revealed changes in dominant symbiont type following bleaching only in Acropora (Cladocopium, Clade C to Durusdinium Clade D) while no such changes were found in other coral genera hosted Clade D. This is the first observation of coral symbiont diversity in the Indian reef.
Mostrar más [+] Menos [-]Responses of salinity and chlorophyll-a to extreme rainfall events in the northwest Arabian Gulf: Emphasis on Shatt Al-Arab Texto completo
2019
Alosairi, Y. | Alsulaiman, N. | Petrov, P. | Karam, Q.
Recent extreme hydrological events, such as high rainfall and storms, have been linked to climate change worldwide due to their relatively uncommon trends, which are generally described as having varying frequencies and higher intensities. Similar extreme rainfall trends were observed in the northwest Arabian Gulf during the 2018–2019 season. Heavy rainfall events have triggered high discharges in the river of Shatt Al-Arab, where, prior to these events, the discharge rate has exhibited a declining trend over the past 40 years. Shatt Al-Arab provides various physical, chemical, and biological functions in the region. In this study, some recent and extensive measurements of salinity and post-processed satellite images of chlorophyll-a in the northwest Arabian Gulf were recorded to assess the response of the region to the higher discharges. The results indicated that the salinity decreased significantly during and after the rainfall events in response to the higher discharges from Shatt Al-Arab. The effects of higher discharges extended over most of Kuwait's coastline, including Kuwait Bay. The chlorophyll-a distributions doubled after the extreme events, emphasising the effects of Shatt Al-Arab. Collectively, the results indicated that the discharge from Shatt Al-Arab during the extreme event exceeded 1400 m³/s, while, in the previous seasons, it rarely exceeded 80 m³/s. The higher discharge levels of discharge would result in various changes in ecology at multiple levels due to the sudden and reversing shift in the hydro-environmental processes.
Mostrar más [+] Menos [-]Marine microplastic-associated bacterial community succession in response to geography, exposure time, and plastic type in China's coastal seawaters Texto completo
2019
Xu, Xiyuan | Wang, Shuai | Gao, Fenglei | Li, Jingxi | Zheng, Li | Sun, Chengjun | He, Changfei | Wang, Zongxing | Qu, Lingyun
Microplastics have emerged as new pollutants in oceans. Nevertheless, information of the long-term variations in the composition of plastic-associated microbial communities in coastal waters remains limited. This study applied high-throughput sequencing to investigate the successional stages of microbial communities attached to polypropylene and polyvinyl chloride microplastics exposed for one year in the coastal seawater of China. The composition of plastisphere microbial communities varied remarkably across geographical locations and exposure times. The dominant bacteria in the plastisphere were affiliated with the Alphaproteobacteria class, particularly Rhodobacteraceae, followed by the Gammaproteobacteria class. Scanning electron microscopy analysis revealed that the microplastics showed signs of degradation. Microbial communities showed adaptations to plastisphere including more diverse microbial community and greater “xenobiotics biodegradation and metabolism” in metabolic pathway analysis. The findings elucidate the long-term changes in the community composition of microorganisms that colonize microplastics and expand the understanding of plastisphere microbial communities present in the marine environment.
Mostrar más [+] Menos [-]Taking advantage of seagrass recovery potential to develop novel and effective meadow rehabilitation methods Texto completo
2019
Alagna, Adriana | D'Anna, Giovanni | Musco, Luigi | Vega Fernández, Tomás | Gresta, Martina | Pierozzi, Natalia | Badalamenti, Fabio
Seagrasses are among the most threatened biomes worldwide. Until now, seagrass rehabilitation success has reached about 38% overall and more effective approaches to restoration are urgently needed. Here we report a novel method to rehabilitate Posidonia oceanica meadows based on observation of the species' natural recovery after disturbance. Posidonia oceanica rhizomes were transplanted on gabions filled with rocks of selected sizes in order to build a firm substrate with topographic complexity in the relevant scale range to propagules. Five techniques were tested, each involving a different anchoring device. The “slot” technique, which uses a wire-net pocket to retain the cuttings, was the most successful, with survival exceeding 85% after thirty months. Branching allowed final shoot survival to reach 422% of initial planting density. This study shows how an in-depth knowledge of species life history processes provides a suitable foundation for developing effective restoration methods that benefit from species recovery ability.
Mostrar más [+] Menos [-]Emerging and traditional organic markers: Baseline study showing the influence of untraditional anthropogenic activities on coastal zones with multiple activities (Ceará coast, Northeast Brazil) Texto completo
2019
Molecular markers are useful tools to characterize natural and anthropogenic impacts on coastal zones. Distribution of n-alkanes showed that the Pacoti River was predominantly influenced by terrigenous input. Distribution of polycyclic aromatic hydrocarbon (PAH) indices showed a mix of natural sources, especially pyrogenic influences. Sterol and hormone levels showed sewage discharge. Integrated geographic assessment showed that pyrogenic process and sewage discharge are predominant along the river because of natural and different anthropogenic activities. The upstream region is influenced by rural activities such as livestock and discharge from the sewage treatment plant, whereas the estuarine region is influenced by urban and industrial activities, predominantly the discharge of treated or untreated sewage, vehicle traffic, and manufacture of red ceramics. On the other hand, on the river mouth, there is the predominance of aquaculture activities. Traditional anthropogenic markers are not sufficient for producing a comprehensive assessment of anthropogenic impacts in areas with multiple activities.
Mostrar más [+] Menos [-]Developing conceptual models that link multiple ecosystem services to ecological research to aid management and policy, the UK marine example Texto completo
2019
Broszeit, Stefanie | Beaumont, Nicola J. | Hooper, Tara L. | Somerfield, Paul J. | Austen, Melanie C.
Our understanding of ecological processes that lead to ecosystem services is still evolving but ecological research aims to understand the linkages between the ecosystem and services. These linkages can affect trade-offs between different ecosystem services. Understanding these linkages, by considering multiple ecosystem services simultaneously supports management of the environment and sustainable use of resources. The UK marine environment is relatively data rich, yet the links between ecosystem and several ecosystem services and linkages between services are poorly described. A workshop with 35 marine scientists was used to create a conceptual model that links ecosystem components and key processes to four services they provide and to highlight trade-offs between them. The model was subsequently further developed to include pressures and mitigating management measures. The models are discussed in terms of their application to marine data to facilitate evidence-based marine management and their usefulness to communicate management measures with managers and stakeholders.
Mostrar más [+] Menos [-]Monitoring the antioxidant activities by extracting the polyphenolic contents of algae collected from the Bosphorus Texto completo
2019
Aslan, Ertugrul | Aksu, Abdullah | Korkmaz, Nagihan Ersoy | Taskin, Omer S. | Caglar, Nuray Balkis
The identification and quantification of ascorbic acid, phenolic acids and flavonoids were carried out simultaneously with a rapid method of reverse-phase high-performance liquid chromatography (RP-HPLC). Total flavonoid contents were being determined by UV–Vis spectrophotometry, and total phenolic contents were determined by UV–Vis spectrophotometry using the Folin-Ciocalteu Reagent (FCR) method.In all of the individual contents and total phenolic content analysis, the best results were obtained with the methanol-water solvent system. The methanol-hexane solvent system was selected as the best for the extraction of total flavonoid contents. The reason for this difference is the flavonoids in the analyzed samples which were the lipophilic character. Examining the algae species, the highest contents were achieved from Ulva lactuca and Ceramium rubrum species. Depending on industrial activity and the population density, regional characteristics have been shown to be effective in the changes of these contents which show antioxidant properties.
Mostrar más [+] Menos [-]Bioaccumulation of metals in oyster (Crassostrea gigas) from Liaodong Bay in Bohai Sea: Seasonal, regional and size-dependent variations Texto completo
2019
Heavy metal concentrations were determined in oyster (C. gigas), planktons and seawater from Liaodong Bay. Samples were collected during spring, summer and autumn. Heavy metal concentrations in oysters, planktons and seawater showed variations depending on season, sampling site and size of the oysters. Heavy metal concentrations in oysters, planktons and seawater were higher in summer and the lowest levels were found in autumn. The maximum levels of Cd and Pb were found in oysters of size-class III while the maximum levels of Cr, Cu and Zn were found in those of size-class II. The minimum levels of Cu and Pb were observed in oysters of size-class I. The minimum levels of Cd were observed in those of size-class II. And the minimum levels of Cr and Zn were observed in those of size-class III. There were significant differences in metal concentrations of oysters, planktons and seawater between sampling sites.
Mostrar más [+] Menos [-]Fecal indicator bacteria levels at beaches in the Florida Keys after Hurricane Irma Texto completo
2019
Roca, Matthew A. | Brown, R Stephen | Solo-Gabriele, Helena M.
Hurricanes cause infrastructure failures which can lead to contamination of impacted areas. The objective of the current study was to evaluate whether Hurricane Irma contributed towards sewage contamination of coastal beaches. Through this study we evaluated indicators of fecal pollution (fecal indicator bacteria [FIB], enterococci and fecal coliform) and physico-chemical parameters (salinity, pH, turbidity, and temperature) in coastal waters of the Florida Keys shortly after the hurricane. To augment available county sampling data, two sets of sampling efforts were conducted; one focused on collecting samples spatially throughout the Keys to assess whether areas closer to hurricane landfall were more highly impacted. The second was to collect temporally intensive samples at one location during falling tide to evaluate the hypothesis of groundwater contamination. Samples were analyzed for FIB using a new method called timed appearance of culture signal (TACS), which was subsequently calibrated using traditional membrane filter and chromogenic substrate methods. Results showed that coastal beach waters were characterized by elevated but sporadic levels of fecal indicator bacteria up to two months after the hurricane. Spikes were not correlated with physico-chemical characteristics of the water. Our temporally intensive sampling effort did not support the hypothesis that groundwater was a source of elevated FIB. Competing factors could have played a role in the sporadic nature of the FIB levels after the hurricane. We suggest that beach erosion may have flushed out sediments at beaches closer to the hurricane landfall location thereby improving water quality during dry conditions. We also suggest that during wet conditions a source of FIB could include runoff from debris staging areas. Preemptive beach closures immediately after the hurricane were justified due to the sporadic nature of FIB contamination.
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