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Resultados 1141-1150 de 4,029
Proteomic analysis of bleached and unbleached Acropora palmata, a threatened coral species of the Caribbean
2016
Ricaurte, Martha | Schizas, Nikolaos V. | Ciborowski, Paweł | Boukli, Nawal M.
There has been an increase in the scale and frequency of coral bleaching around the world due mainly to changes in sea temperature. This may occur at large scales, often resulting in significant decline in coral coverage. In order to understand the molecular and cellular basis of the ever-increasing incidence of coral bleaching, we have undertaken a comparative proteomic approach with the endangered Caribbean coral Acropora palmata. Using a proteomic tandem mass spectrometry approach, we identified 285 and 321 expressed protein signatures in bleached and unbleached A. palmata colonies, respectively, in southwestern Puerto Rico. Overall the expression level of 38 key proteins was significantly different between bleached and unbleached corals. A wide range of proteins was detected and categorized, including transcription factors involved mainly in heat stress/UV responses, immunity, apoptosis, biomineralization, the cytoskeleton, and endo–exophagocytosis. The results suggest that for bleached A. palmata, there was an induced differential protein expression response compared with those colonies that did not bleach under the same environmental conditions.
Mostrar más [+] Menos [-]Dynamic fugacity model for accidental oil release during Arctic shipping
2016
Afenyo, Mawuli | K̲h̲ān, Faiṣal | Veitch, Brian | Yang, Ming
Improved understanding of ecological risk associated with Arctic shipping would help advance effective oil spill prevention, control, and mitigation strategies. Ecological risk assessment involves analysis of a release (oil), its fate, and dispersion, and the exposure and intake of the contaminant to different receptors. Exposure analysis is a key step of the detailed ecological risk assessment, which involves the evaluation of the concentration and persistence of released pollutants in the media of contact. In the present study, a multimedia fate and transport model is presented, which is developed using a fugacity-based approach. This model considers four media: air, water, sediment, and ice. The output of the model is the concentration of oil (surrogate hydrocarbons-naphthalene) in these four media, which constitutes the potential exposure to receptors. The concentration profiles can subsequently be used to estimate ecological risk thereby providing guidance to policies for Arctic shipping operations, ship design, and ecological response measures.
Mostrar más [+] Menos [-]Phosphorus release from coastal sediments: Impacts of the oxidation-reduction potential and sulfide
2016
Yi, So-yŏn | Sheng, Yanqing | Yang, Jian | Burton, Edward D.
The release of phosphorus (P) from benthic sediments can affect the P content, nutrient status and quality of overlying waters in coastal ecosystem. This study was carried out to investigate the influence of oxidation-reduction potential (ORP) and sulfide on P release from sediments in the coastal estuary of the Yuniao River, China. The results showed that ferric iron-bound P was the main P burial phase in the sediments. The P concentration in overlying water increased with ORP decrease and sulfide increase, displaying a significant linear correlation with the ORP and sulfide concentration. The results indicate that decreased ORP may elevate the zero equilibrium phosphorus concentration, enhancing the capability of P release. And increased sulfide may react or capture reactive iron in sediments, reducing the P adsorption capacity and accelerating P release. Therefore, the control of ORP and sulfide production is important in the sink/source conversion of P in coastal sediments.
Mostrar más [+] Menos [-]The protective service of mangrove ecosystems: A review of valuation methods
2016
Barbier, Edward B.
Concern over the loss of mangrove ecosystems often focuses on their role in protecting coastal communities from storms that damage property and cause deaths and injury. With climate change, mangrove loss may also result in less protection against coastal storms as well as sea-level rise, saline intrusion and erosion. Past valuations of the storm protection benefit of mangroves have relied on the second-best replacement cost method, such as estimating this protective value with the cost of building human-made storm barriers. More reliable methods instead model the production of the protection service of mangroves and estimate its value in terms of reducing the expected damages or deaths avoided by coastal communities. This paper reviews recent methods of valuing the storm protection service of mangroves and their role in protecting coastal areas and communities of tropical developing countries.
Mostrar más [+] Menos [-]Suspended particulate matter fluxes along with their associated metals, organic matter and carbonates in a coastal Mediterranean area affected by mining activities
2016
Helali, Mohamed Amine | Zaaboub, Noureddine | Oueslati, Walid | Added, Ayed | Aleya, Lotfi
A study of suspended particulate matter (SPM) fluxes along with their associated metals, organic matter and carbonates, was conducted off the Mejerda River outlet in May 2011 and in March and July 2012 at depths of 10, 20 and 40m using sediment traps. SPM fluxes are more significant near the Mejerda outlet, especially in winter, but dissipate further offshore. Normalization reveals that the Mejerda is a major source of Pb, Zn, Cd, Cu, Ni, and Co, all of which are the result of human activities. In contrast, Fe, Mn and N are of authigenic origin. The enrichment factor shows that Pb, Zn and especially Cd are the most highly polluting metals off the Mejerda outlet. This confirms the trend observed on the shores of the Mejerda prodelta and is consistent with the type of mining activities conducted in the Mejerda catchment.
Mostrar más [+] Menos [-]Fishes as indicators of untreated sewage contamination in a Mexican coastal lagoon
2016
Aguilar-Betancourt, Consuelo M. | González Sansón, Gaspar | Kidd, Karen A. | Munkittrick, Kelly R. | Curry, R Allen | Kosonoy-Aceves, Daniel | Lucano-Ramírez, Gabriela | Ruiz-Ramírez, Salvador | Flores-Ortega, Juan R.
Lagoons are important nursery habitats for fishes but are often sites of intense human activity including wastewater discharges. The goal of this research was to compare stable nitrogen (δ15N) and carbon (δ13C) isotopes, total mercury (THg) and other metal levels in four selected fish species among sites with different levels of untreated sewage discharge inside Barra de Navidad coastal lagoon in the Mexican Pacific. Three species from sites heavily impacted by sewage showed higher δ15N and δ13C compared to those from non-impacted sites. In addition, the highest concentrations of THg were present in fish of two species (Sciades guatemalensis and Diapterus brevirostris) collected at the two most impacted sites, and exceeded the 0.2μg/g ww threshold believed to be protective of adult and juvenile fish. No individuals of Achirus mazatlanus and Mugil curema exceeded this threshold, and liver somatic index and condition did not distinguish high from low impacted sites for all species. In general, the metal levels differed among species but not sites, and were lower than what has been measured in fishes elsewhere. The study also provides the first information on several fish species for coastal areas of Mexico, suggests that THg and isotopes can distinguish sewage-impacted sites, and can serve as a baseline for future studies.
Mostrar más [+] Menos [-]Sewage contamination of sediments from two Portuguese Atlantic coastal systems, revealed by fecal sterols
2016
Rada, Jesica P.A. | Duarte, Armando C. | Pato, Pedro | Cachada, Anabela | Carreira, Renato S.
Fecal sterols in sediments were used to assess the degree of sewage contamination in Ria de Aveiro lagoon and Mondego River estuary for the first time. Coprostanol, the major fecal sterol, averaged 1.82±4.12μgg−1, with maxima of 16.6μgg−1. The northwestern sector of the Ria and a marina at Mondego estuary showed the highest level of sewage contamination. This scenario was confirmed by several diagnostic ratios based on fecal sterols and other phytosterols. Our data revealed that in spite of the improvements achieved in the last decades, there is still a need for control the organic inputs into the aquatic environment in the studied regions.
Mostrar más [+] Menos [-]Historical record of lead accumulation and source in the tidal flat of Haizhou Bay, Yellow Sea: Insights from lead isotopes
2016
Zhang, Rui | Guan, Minglei | Shu, Yujie | Shen, Liya | Chen, Xixi | Zhang, Fan | Li, Tiegang
In order to investigate the historical records of lead contamination and source in coastal region of Haizhou Bay, Yellow Sea, a sediment core was collected from tidal flat, dated by 210Pb and 137Cs. Lead and its stable isotopic ratios were determined. The profiles of enrichment factor (EF) and Pb isotope ratios showed increasing trend upward throughout the core, correlating closely with the experience of a rapid economic and industrial development of the catchment. According to Pb isotopic ratios, coal combustion emission mainly contributed to the Pb burden in sediments. Based on end-member model, coal combustion emission dominated anthropogenic Pb sources in recent decades contributing from 48% to 67% in sediment. And the contribution of leaded gasoline was lower than 20%. A stable increase of coal combustion source was found in sediment core, while the contribution of leaded gasoline had declined recently, with the phase-out of leaded gasoline in China.
Mostrar más [+] Menos [-]Abiotic factors influencing biomass accumulation of green tide causing Ulva spp. on Pyropia culture rafts in the Yellow Sea, China
2016
Keesing, John K. | Liu, Dongyan | Shi, Yajun | Wang, Yujue
Annually recurrent green-tides in the Yellow Sea have been shown to result from direct disposal into the sea of fouling Ulva from Pyropia aquaculture. The role abiotic factors play in Ulva biomass accumulation on rafts was studied to find ways to mitigate this problem. Dissolved inorganic nitrogen (DIN) was very high at all sites, but the highest Ulva biomass was associated with the lowest DIN and anthropogenic N. Under luxuriant background nutrient conditions, variability in temperature and periods of emersion, rather than pH, light and salinity determined Ulva biomass. Two dominant species of Ulva displayed differing tolerances to temperature and desiccation which helped explain why Ulva prolifera dominates floating green-tides. Rather than trying to mitigate green-tides only by reducing nutrient pollution, an earlier harvest of Pyropia in southern Jiangsu Province especially before temperatures increase greatly above 10°C during April, could reduce the biomass of U. prolifera disposed from rafts.
Mostrar más [+] Menos [-]Lead, cadmium and mercury in the blood of the blue-footed booby (Sula nebouxii) from the coast of Sinaloa, Gulf of California, Mexico
2016
Lerma, Miriam | Castillo-Guerrero, José Alfredo | Ruelas-Inzunza, Jorge | Fernández, Guillermo
We used blood samples of the Blue-footed Booby, considering sex (female and male) and age-class (adult and chick) of individuals at different breeding stages during two breeding seasons (2010–2011 and 2011–2012) in Isla El Rancho, Sinaloa, to determine lead, cadmium, and mercury concentrations. Lead and cadmium concentrations were below our detection limit (0.05 and 0.36ppm, respectively). A higher concentration of mercury was found in early stages of breeding, likely related to changes in mercury environmental availability. Mercury concentrations in adults did not relate with their breeding output. Males and adults had higher mercury concentration than females and chicks. We provide information of temporal, sex and age-related variations in the concentrations of mercury in blood of the Blue-footed Booby.
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