خيارات البحث
النتائج 561 - 570 من 1,506
Ecological quality assessment of small estuaries from the Portuguese coast based on benthic macroinvertebrate assemblages indices
2012
Cardoso, Inês | Fonseca, Luís Cancela da | Cabral, Henrique N.
Benthic macroinvertebrates communities are the most consistently emphasized biotic component of aquatic ecosystems and are one of the biological indicators required for assessment by the European Water Framework Directive. In this context, several indices based on these communities have been developed in order to assess ecological quality of estuarine systems. In the present work we used AMBI, M-AMBI, BENTIX and BAT to distinguish ecological status of five small estuarine systems of the Portuguese south and southwest coasts. Although indices outputs did not differ between systems and sampling seasons, results indicated that the metrics in which these indices are based could differentiate community structures as a result of two main gradients that force these communities: the natural variability, and the anthropogenic impact.
اظهر المزيد [+] اقل [-]Trends in marine debris along the U.S. Pacific Coast and Hawai’i 1998–2007
2012
Ribic, Christine A. | Sheavly, Seba B. | Rugg, David J. | Erdmann, Eric S.
We assessed amounts, composition, and trends of marine debris for the U.S. Pacific Coast and Hawai’i using National Marine Debris Monitoring Program data. Hawai’i had the highest debris loads; the North Pacific Coast region had the lowest debris loads. The Southern California Bight region had the highest land-based debris loads. Debris loads decreased over time for all source categories in all regions except for land-based and general-source loads in the North Pacific Coast region, which were unchanged. General-source debris comprised 30–40% of the items in all regions. Larger local populations were associated with higher land-based debris loads across regions; the effect declined at higher population levels. Upwelling affected deposition of ocean-based and general-source debris loads but not land-based loads along the Pacific Coast. LNSO decreased debris loads for both land-based and ocean-based debris but not general-source debris in Hawai’i, a more complex climate-ocean effect than had previously been found.
اظهر المزيد [+] اقل [-]Using EUNIS habitat classification for benthic mapping in European seas: Present concerns and future needs
2012
Galparsoro, Ibon | Connor, David W. | Borja, Angel | Aish, Annabelle | Amorim, Patricia | Bajjouk, Touria | Chambers, Caroline | Coggan, Roger | Dirberg, Guillaume | Ellwood, Helen | Evans, Douglas | Goodin, Kathleen L. | Grehan, Anthony | Haldin, Jannica | Howell, K. L. (Kerry L.) | Jenkins, Chris | Michez, Noëmie | Mo, Giulia | Buhl-Mortensen, Pål | Pearce, B. (Bryony) | Populus, Jacques | Salomidi, Maria | Sánchez, Francisco | Serrano, Alberto | Shumchenia, Emily | Tempera, Fernando | Vasquez, Mickaël
The EUNIS (European Union Nature Information System) habitat classification system aims to provide a common European reference set of habitat types within a hierarchical classification, and to cover all terrestrial, freshwater and marine habitats of Europe. The classification facilitates reporting of habitat data in a comparable manner, for use in nature conservation (e.g. inventories, monitoring and assessments), habitat mapping and environmental management. For the marine environment the importance of a univocal habitat classification system is confirmed by the fact that many European initiatives, aimed at marine mapping, assessment and reporting, are increasingly using EUNIS habitat categories and respective codes. For this reason substantial efforts have been made to include information on marine benthic habitats from different regions, aiming to provide a comprehensive geographical coverage of European seas. However, there still remain many concerns on its applicability as only a small fraction of Europe’s seas are fully mapped and increasing knowledge and application raise further issues to be resolved. This paper presents an overview of the main discussion and conclusions of a workshop, organised by the MeshAtlantic project, focusing upon the experience in using the EUNIS habitats classification across different countries and seas, together with case studies. The aims of the meeting were to: (i) bring together scientists with experience in the use of the EUNIS marine classification and representatives from the European Environment Agency (EEA); (ii) agree on enhancements to EUNIS that ensure an improved representation of the European marine habitats; and (iii) establish practices that make marine habitat maps produced by scientists more consistent with the needs of managers and decision-makers. During the workshop challenges for the future development of EUNIS were identified, which have been classified into five categories: (1) structure and hierarchy; (2) biology; (3) terminology; (4) mapping; and (5) future development. The workshop ended with a declaration from the attendees, with recommendations to the EEA and European Topic Centre on Biological Diversity, to take into account the outputs of the workshop, which identify weaknesses in the current classification and include proposals for its modification, and to devise a process to further develop the marine component of the EUNIS habitat classification.
اظهر المزيد [+] اقل [-]Biomarkers responses in muscle of Senegal sole (Solea senegalensis) from a heavy metals and PAHs polluted estuary
2012
Oliva, Milagrosa | Perales, José Antonio | Gravato, Carlos | Guilhermino, Lucia | Galindo-Riaño, María Dolores
The biochemical responses in muscle, such as the enzymatic activities of acetylcholinesterase, lactate dehydrogenase and isocitrate dehydrogenase, were studied in sole (Solea senegalensis) collected in Huelva estuary (SW Spain), in the vicinity of a petrochemical and mining industry. The sampling sites showed different type and degree of pollution. The results demonstrated significant differences in muscle activities of AChE and IDH in Odiel and Tinto Rivers compared to control fish. LDH activity did not show any difference between sampling sites. Significant correlations were established between some biomarkers and heavy metals: AChE was correlated with Pb, Cd and Cu concentrations in water; IDH activity was correlated with Cd and Cu concentrations in water and As, Pb and Cd concentrations in sediments; LDH activity was correlated with As and Zn concentration in water and Cd concentration in sediment. Only one correlation was established between the biomarkers analysed and the concentrations of PAHs: benzo(b)fluoranthene concentration in sediment and IDH.
اظهر المزيد [+] اقل [-]Historical changes in trace metals and hydrocarbons in nearshore sediments, Alaskan Beaufort Sea, prior and subsequent to petroleum-related industrial development: Part I. Trace metals
2012
Naidu, A Sathy | Blanchard, Arny L. | Misra, Debasmita | Trefry, John H. | Dasher, Douglas H. | Kelley, John J. | Venkatesan, M Indira
Concentrations of Fe, As, Ba, Cd, Cu, Cr, Pb, Mn, Ni, Sn, V and Zn in mud (<63μm size), and total and methyl Hg in gross sediment are reported for Arctic Alaska nearshore. Multivariate-PCA analysis discriminated seven station clusters defined by differences in metal concentrations, attributed to regional variations in granulometry and, as in Elson Lagoon, to focused atmospheric fluxes of contaminants from Eurasia. In Colville Delta-Prudhoe Bay, V increase was noted in 1985 and 1997 compared to 1977, and Ba increase from 1985 to 1997. Presumably the source of increased V is the local gas flaring plant, and the elevated Ba is due to barite accumulation from oil drilling effluents. In Prudhoe Bay, concentration spikes of metals in ∼1988 presumably reflect enhanced metals deposition following maximum oil drilling in 1980s. In summary, the Alaskan Arctic nearshore has remained generally free of metal contamination despite petroleum-related activities in past 40years.
اظهر المزيد [+] اقل [-]Papuan Bird’s Head Seascape: Emerging threats and challenges in the global center of marine biodiversity
2012
Mangubhai, Sangeeta | Erdmann, Mark V. | Wilson, Joanne R. | Huffard, Christine L. | Ballamu, Ferdiel | Hidayat, Nur Ismu | Hitipeuw, Creusa | Lazuardi, Muhammad E. | Muhadjir, | Pada, Defy | Purba, Gandi | Rotinsulu, Christovel | Rumetna, Lukas | Sumolang, Kartika | Wen, Wen
The Bird’s Head Seascape located in eastern Indonesia is the global epicenter of tropical shallow water marine biodiversity with over 600 species of corals and 1,638 species of coral reef fishes. The Seascape also includes critical habitats for globally threatened marine species, including sea turtles and cetaceans. Since 2001, the region has undergone rapid development in fisheries, oil and gas extraction, mining and logging. The expansion of these sectors, combined with illegal activities and poorly planned coastal development, is accelerating deterioration of coastal and marine environments. At the same time, regency governments have expanded their marine protected area networks to cover 3,594,702ha of islands and coastal waters. Low population numbers, relatively healthy natural resources and a strong tenure system in eastern Indonesia provide an opportunity for government and local communities to collaboratively manage their resources sustainably to ensure long-term food security, while meeting their development aspirations.
اظهر المزيد [+] اقل [-]Upregulation of hypoxia-inducible factor (HIF)-1α and HIF-2α mRNA levels in dragonet Callionymus valenciennei exposed to environmental hypoxia in Tokyo Bay
2012
Kodama, Keita | Saydur Rahman, Md | Horiguchi, Toshihiro | Thomas, Peter
There is an urgent need to develop reliable biomarkers of environmental hypoxia exposure in marine organisms in order to assess the ecological impacts of the marked increase in coastal hypoxia worldwide. Full-length hypoxia-inducible factor HIF-1α and HIF-2α cDNAs were cloned and characterized from dragonet Callionymus valenciennei, a representative epibenthic teleost inhabiting hypoxic areas in Tokyo Bay, to evaluate the potential utility of their transcript levels as biomarkers of environmental hypoxia exposure. HIF-1α and HIF-2α transcript levels in the livers of dragonet collected from hypoxic sites in Tokyo Bay were increased several-fold over those collected from nonhypoxic areas. Further, HIF-1α and HIF-2α mRNA levels were increased in dragonet livers after 7days exposure to hypoxia in a controlled laboratory experiment, and they declined to control levels within 24h of restoration to normoxic conditions. Our findings suggest HIF-1α and HIF-2α transcript levels are potentially useful biomarkers of environmental hypoxia exposure.
اظهر المزيد [+] اقل [-]Chesapeake Bay nutrient pollution: Contribution from the land application of sewage sludge in Virginia
2012
Land, Lynton S.
Human health concerns and the dissemination of anthropogenic substances with unknown consequences are the reasons most often given why disposal of municipal sewage sludge in landfills or using the organic waste as biofuel is preferable to land application. But no “fertilizer” causes more nitrogen pollution than sludge when applied according to Virginia law. Poultry litter is the only other “fertilizer” that causes more phosphorus pollution than sludge. Cost savings by the few farmers in Virginia who use sludge are far less than the costs of the nitrogen pollution they cause. A ban on the land application of all forms of animal waste is very cost-effective and would reduce Chesapeake Bay nutrient pollution by 25%.
اظهر المزيد [+] اقل [-]Occurrence and distribution of organochlorine residues in surface sediments of the Candarli Gulf (Eastern Aegean)
2012
Pazi, Idil | Kucuksezgin, Filiz | Tolga Gonul, L.
The residual levels of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were determined in surface sediments collected from Candarli Gulf. Total concentrations of OCPs and PCBs in sediments ranged from 10.2 to 57.3 and 2.8 to 205ngg⁻¹dwt, respectively. DDTs in sediments were derived from the aged and weathered agricultural soils in 61% of the sampling stations while 39% of the sites originated from the recent DDT inputs. Their concentrations appeared to be relatively low by global standards and only sediments receiving the impact from the Bakircay River and petrochemical industry approached the sediment quality guidelines for PCBs and DDTs. Based on ERL/ERM guidelines, DDT and PCBs posed ecological risk to the bottom-dwelling consumers.
اظهر المزيد [+] اقل [-]Parasite communities in the red mullet, Mullus barbatus L., respond to small-scale variation in the levels of polychlorinated biphenyls in the Western Mediterranean
2012
Carreras-Aubets, Marta | Montero, Francisco Esteban | Kostadinova, Aneta | Carrassón, Maite
We examined parasite populations and communities in the Mediterranean sentinel fish species, Mullus barbatus, sampled at a small-scale PCB gradient at the shelf sediments off Catalonian coasts of the Western Mediterranean. A recurrent feature at both the population and community level was the differentiation of the samples along the increasing PCB levels simultaneously registered in the sediments. Both directly transmitted ectoparasites and endoparasites with complex life-cycles transmitted via food chains exhibited a decrease in abundance with the increase in PCB levels. Parasite numerical responses translated into significant differences in infracommunity structure with decreasing predictability associated with increasing PCB levels. The abundance of two species, the specialist Opecoeloides furcatus and the generalist nematode Hysterothylacium fabri, contributed substantially to the observed dissimilarity between infracommunity samples along the gradient. The observed parasite responses to moderate levels of pollution were simultaneously validated by both chemical monitoring and effect biomarkers.
اظهر المزيد [+] اقل [-]