937 resultados para Jehol Biota
Resumo:
A subject of a change of authorised limits in 1994 for the discharge of liquid radioactive waste by the reprocessing plant Sellafield (UK) was an increase of these limits for certain radionuclides (3H, 14C, 60Co, 99Tc and 129I). It is investigated now how the radioactivity in marine biota from the North Sea and subsequently the public radiation exposure by ingestion has developed in the years since 1994. This is based on a compartment model for the Northeast Atlantic. Discharges of the reprocessing plants Dounreay (UK) and La Hague (F) are included in the assessment. It is deduced that about 60 % of 137Cs in the North Sea originate presently in the remobilisation of old Sellafield discharges from the Irish Sea sediment. A comparison with measured biota data shows that the model is conservative in the most cases. The public radiation exposure from ingestion of fish, crustaceans and molluscs from the central North Sea as the sum over 12 considered radionuclides has decreased from 1992 to 1998 from 0,13 to 0,08 μSv·y–1. For the southward and northward joined regions it was a little bit smaller with a similar decreasing trend.
Resumo:
Trace metals constitute a major form of water pollutant that can adversely affect fish production. The potentially toxic metals have been identified as lead, zinc, copper, arsenic, antimony, mercury beryllium, barium, cadmium, chromium, nickel, selenium among others. Preliminary laboratory studies have been directed to the determination of traces of lead in the aquatic biota and its toxicity. There are indications that the levels reported in effluents from some of the industries may be above the tolerant limits of local fish species and organisms that make up their food. Metal pollution could become a serious problem to freshwater fisheries in the future as a result of increasing urbanization and industrialization, unless efforts are made to prevent it
Resumo:
Die 150. Reise des FFS "Walther Herwig III" wurde im Juli/August 1994 als Gemeinschaftsprojekt der Institute für Biochemie und Technologie und dem Institut für Fischereiökologie durchgeführt, um einen Überblick über die Schadstoffbelastung (anorganische und organische Schadstoffe, Radioaktivität) von Wasser, Sediment und Biota in der Barentssee zu erhalten. Das Institut für Biochemie und Technologie hat in diesem Forschungsprogramm den Teil "Bestimmung der Schwermetallgehalte im verzehrbaren Anteil (Filet) von Fischen und anderen Meerestieren" übernommen.
Resumo:
Fragen, die die Gewässerökologie und die Gewässergütesituation der Elbe betreffen, werden in der Bundesrepublik Deutschland einvernehmlich in der Arbeitsgemeinschaft für die Reinhaltung der Elbe (ARGE ELBE) der sieben Elbanrainerländer behandelt. Die Wassergütestelle Elbe (WGE) koordiniert als gemeinsame Einrichtung der ARGE ELBE die Überwachung des Stromes in den vier Kompartimenten Wasser, Schwebstoffe, Sediment und Biota. Im Rahmen der Biota-Untersuchungen wird auch die Belastungssituation des Elbfisches Brassen (Abramis brama L.) erfaßt.
Resumo:
Historia del primer Laboratorio de Ictiofisiología de la Argentina. History of the first Laboratory of Icthyophysiology in Argentina.
Resumo:
El pejerrey Odontesthes bonariensis es uno de los peces de aguas continentales más emblemáticos de la Argentina y una de las especies más estudiada desde diferentes aspectos: ecológico, sistemático, morfológico, fisiológico, genético, etc. (López et al. 1991). Durante los años 1891 y 1892 se realizaron las primeras experiencias de piscicultura,lográndose por primera vez la reproducción artificial en 1904. Su amplia distribución actual es consecuencia de las siembras que se realizaron desde el antiguo Vivero de Piscicultura del Ministerio de Agricultura y Ganadería de la Nación y de la Estación Hidrobiológica del Ministerio de Asuntos Agrarios de la provincia de Buenos Aires, ambos establecimientos ubicados en la ciudad de Chascomús. En el presente trabajo se realiza una aproximación a la historia de la piscicultura del pejerrey en Chascomús, la que se divide en tres períodos: 1) Antecedentes de piscicultura, importancia de la pesca comercial en el sistema de lagunas Encadenadas de Chascomús y primeras medidas tomadas para conservar la explotación de las lagunas hacia fines del siglo XIX. 2) Etapa del antiguo Vivero (Ministerio de Agricultura de la Nación), desde 1904 hasta 1939. 3) Etapa de la Estación Hidrobiológica (Ministerio de Asuntos Agrarios, provincia de Buenos Aires), desde 1943 hasta el presente.
Resumo:
This series will include all those people who, by means of their contributions, great and small, played a part in the consolidation of ichthyology in Argentina. The general plan of this work consists of individual factsheets containing a list of works by each author, along with reference bibliography and, whenever possible, personal pictures and additional material. The datasheets will be published primarily in chronological order, although this is subject to change by the availability of materials for successive editions. This work represents another approach for the recovery and revalorization of those who set the foundations of Argentine ichthyology while in diverse historical circumstances. I expect this to be the beginning of a major work that achieves the description of such a significant part of the history of natural sciences in Argentina.
Resumo:
This series will include all those people who, by means of their contributions, great and small, played a part in the consolidation of ichthyology in Argentina. The general plan of this work consists of individual factsheets containing a list of works by each author, along with reference bibliography and, whenever possible, personal pictures and additional material. The datasheets will be published primarily in chronological order, although this is subject to change by the availability of materials for successive editions. This work represents another approach for the recovery and revalorization of those who set the foundations of Argentine ichthyology while in diverse historical circumstances. I expect this to be the beginning of a major work that achieves the description of such a significant part of the history of natural sciences in Argentina.
Resumo:
This series will include all those people who, by means of their contributions, great and small, played a part in the consolidation of ichthyology in Argentina. The general plan of this work consists of individual factsheets containing a list of works by each author, along with reference bibliography and, whenever possible, personal pictures and additional material. The datasheets will be published primarily in chronological order, although this is subject to change by the availability of materials for successive editions. This work represents another approach for the recovery and revalorization of those who set the foundations of Argentine ichthyology while in diverse historical circumstances. I expect this to be the beginning of a major work that achieves the description of such a significant part of the history of natural sciences in Argentina.
Ecosystem study Altenwoerth: impacts of a hydroelectric power-station on the River Danube in Austria
Resumo:
The aim of this article is to briefly describe the effects of the Altenwoerth Barrage, on the River Danube, on some physical variables and their consequent effects on water chemistry and the biota of the river. The methods used for biological sampling are summarised, especially those used in the limnological part of the study, and the macroinvertebrate and fish fauna listed. Comparisons are then made between the impounded section of river immediately above the dam and two unimpounded free-flowing sections of the river. Further developments on the Danube are considered.
Resumo:
Changes in sustainability of aquatic ecosystems are likely to be brought about by the global warming that has been widely predicted. In this article, the effects of water temperature on water-bodies (lakes, oceans and rivers) are reviewed followed by the effects of temperature on aquatic organisms. Almost all aquatic organisms require exogenous heat before they can metabolise efficiently. An organism that is adapted to warm temperatures will have a higher rate of metabolism of food organisms and this increases feeding rate. In addition, an increase in temperature raises the metabolism of food organisms, so food quality can be altered. Where populations have a different tolerance to temperature the result is habitat partitioning. One effect of prolonged high temperature is that it causes water to evaporate readily. In the marine littoral this is not an important problem as tides will replenish water in pools. Small rain pools are found in many tropical countries during the rainy season and these become incompletely dried at intervals. The biota of such pools must have resistant stages within the life cycle that enable them to cope with periods of drying. The most important potential effects of global warming include (i) the alteration of existing coastlines, (ii) the development of more deserts on some land masses, (iii) higher productivity producing higher crop production but a greater threat of algal blooms and (iv) the processing of organic matter at surface microlayers.
Resumo:
The Anambra River is the largest tributary of the lower Niger River below Lukoja. Between the months of May and November the river is subject to seasonal flooding from heavy precipitation and land runoff into the drainage system. During the flood phase, pools form on the floodplains (known as the fadama) and these pools receive materials and biota from the main river channel. The biota often includes representatives of freshwater vertebrates (including fishes) and invertebrates. On this brief note, the authors report on the macroinvertebrates found during preliminary studies on four fadama pools during the non-flood season between December 1994 and April 1995. 523 specimens were collected, of which 86% were arthropods, 9% were annelids (mostly Tubifex and Nais) and a few leeches (Hirudo), and 5% were gastropod molluscs of the arthropods, 75% were insects particularly Hemiptera and Diptera.
Resumo:
Under the EC Water Framework Directive (WFD), each Member State is required to devise a comprehensive national monitoring programme for surface waters, incorporating hydromorphological, physico-chemical and biological elements. This paper describes one aspect of the biota - the macrophyte flora - to classify standing waters and to monitor their water quality. The evolution of this method is described and suggestions for its future development are made.
Resumo:
A Bacia sedimentar do Araripe é uma das mais ricas localidades fossilíferas do mundo e representa algumas das principais fases da evolução tectônica ligadas ao processo de abertura do Atlântico Sul. Essa bacia se subdivide em dois pacotes estratigráficos distintos: o Grupo Cariri (constituído pelas formações Cariri, Missão Velha e Rio Batateiras) e o Grupo Araripe (constituído pelas formações Crato, Ipubi, Santana e Exu). No caso do Grupo Cariri, apenas a Formação Missão Velha (= Brejo Santo para alguns autores) apresenta restos de peixes fósseis. Essa fauna, típica da fase rift da separação da parte oeste do Gondwana, pode ser comparada à ictiofauna já descrita no Grupo Bahia e à fauna encontrada em diversas bacias interiores do Nordeste do Brasil. O presente trabalho constou da realização de coletas na Formação Missão Velha, identificação, preparação e descrição dos espécimes coletados; comparação da paleoictiofauna dessa formação com a de outras bacias de mesma idade; análise da distribuição paleobiogeográfica dos grupos ali presentes. Apesar de desarticulados, foram identificados seis táxons de peixes, assim como fragmentos de teleósteos não identificados. Os táxons identificados a partir do material coletado são: dentes, espinhos cefálicos e espinhos de nadadeira dorsal de Hybodontiformes; escamas, dentes e ossos desarticulados de Lepidotes sp.; escamas de Pleuropholidae; diversos ossos desarticulados de Mawsonia cf. gigas; placa dentária e outros ossos isolados de Ceratodus sp. Essa fauna é muito importante, pois representa uma biota lacustrina do Neocomiano do Brasil, depositada durante os estágios pré-rift/rift da separação do oeste do Gondwana. Durante a fase pré-rift e rift pode ser observada uma correlação estratigráfica entre a Formação Missão Velha e as bacias marginais da África ocidental. Portanto, a biota presente na Formação Missão Velha auxilia a compreensão da diversidade faunística presente nos estágios pré-rift e rift do Brasil e da África.
Resumo:
Estudos ambientais têm demonstrado que substâncias geradas por processos antropogênicos podem causar efeitos prejudiciais interferindo no equilíbrio natural do ecossistema. Manguezais exercem funções essenciais nos ciclos biológicos e constituem Área de Proteção Permanente no Brasil. Infelizmente, eles estão sendo degradados acima do seu limite de suporte, levando a uma redução das áreas remanescentes no mundo. Este trabalho apresenta os resultados de mutagenicidade e genotoxicidade observados em quatro amostragens (PI, V, O e PII) entre 2009 e 2010, relacionados com metais e hidrocarbonetos policíclicos aromáticos (HPA) em sedimento de mangue para a caracterização dos valores de referência. Os testes de genotoxicidade foram feitos a partir de hemócitos do caranguejo Goniopsis cruentata, coletados em um ecossistema potencialmente não poluído do Brasil, localizado no sul do Rio de Janeiro (Parati/RJ), chamado de "Saco do Mamanguá". Coleta, armazenamento e manipulação dos sedimentos e material biológico de cinco pontos de amostragem (M1- M5) foram processados de acordo com normas norte-americanas reconhecidas. A identificação das substâncias químicas foi realizada com extratos de sedimentos e utilizada no bioensaio Salmonella/microssoma (Kado). A avaliação de potenciais danos genotóxicos estabelecidos foi realizada através do Teste de Micronúcleo, que apresentou valores significativos na amostra V. Resultados negativos foram observados para as cepas de Salmonella typhimurium TA97, TA98, TA100 e TA102, tanto na ausência quanto na presença de fração de metabolização exógena de mamíferos (S9 mix 4%) em todas as análises. A quantificação por cromatografia gasosa com detecção por espectrometria de massas dos 16 HPA prioritários em termos de conservação ambiental apresentou valores baixos nas duas primeiras amostragens (PI e V) e nulos nas coletas seguintes (O e PII), nos mesmos pontos. De acordo com os valores utilizados nos Estados Unidos e Canadá como referência, os detectados por nós não são considerados como toxicantes ambientais positivos, com exceção do Benzo(a)pireno, que em M1V apresentou valores um pouco acima do limite a partir do qual já podem ser observados pequenos efeitos na biota. A análise dos metais (Cd, Cr, Cu, Fe, Mn, Ni, Pb e Zn) por Espectrometria de Absorção Atômica inicialmente realizada com a água intersticial foi melhor interpretada a partir da matriz sedimento. Este estudo contribuirá com a implementação de indicadores para valores de referência em mangue.