971 resultados para Seedling limitation


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The California fishery for red sea urchins, Strongylocentrotus franciscanus, has undergone explosive growth in recent years and is approaching full exploitation. Thus, there is considerable interest in enhancing stocks to maintain a high rate of landings. Fishable stocks of red sea urchins in different areas appear to be limited at three stages in their life history: By the availability of larvae, by the survival of newly settled to mid-sized animals, and by the food available to support growth and reproduction of larger animals. Here I review other efforts, notably the extensive Japanese work, to enhance fishable stocks of benthic marine invertebrates, and consider the potential options for red sea urchins at different points of limitation. These include collecting or culturing seed for outplanting, physical habitat improvement measures, improving the food supply, and conservation measures to protect existing stocks until alternate methods are proven and in place. The options are compared in terms of biological feasibility, capital and labor requirements, and potential implications for change in the structure of the fishing industry.

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O objetivo deste estudo foi avaliar ex vivo a extrusão bacteriana apical após instrumentação mecanizada com sistemas reciprocantes de instrumento único e movimento reciprocante (WaveOne and Reciproc) comparados a um sistema multi-instrumentos (BioRaCe). Quarenta e cinco incisivos inferiores humanos unirradiculares, ovais e de anatomia semelhante foram utilizados. Os dentes foram acessados e seus canais radiculares foram contaminados com uma suspensão de Enterococcus faecalis e incubados por 30 dias possibilitando crescimento bacteriano em biofilme. Os dentes contaminados foram divididos em três grupos com 15 espécimes cada (RE - Reciproc, WO -WaveOne e BR - BioRaCe). Foram utilizados oito dentes para grupos controle de crescimento bacteriano positivo e negativo. As bactérias extruídas apicalmente durante a instrumentação foram coletadas em frascos de vidro contendo 0,9% de NaCl. As amostras microbiológicas foram retiradas dos frascos e incubadas em meio BHI ágar, durante 24 horas. O crescimento bacteriano foi contado e os resultados foram expressos em unidades formadoras de colônia (UFC). Os dados foram analisados pelos testes estatísticos de Wilcoxon e Kruskal-Wallis. Não houve diferença estatisticamente significante no número de UFC entre os dois sistemas reciprocantes (p>0,05). Em contrapartida, o sistema de instrumentos rotatórios mostrou uma quantidade de UFC significativamente maior do que os dois outros grupos (p <0,05). A partir da análise dos resultados e dentro das limitações deste estudo foi possível concluir que todos os sistemas de instrumentação testados extruem bactérias apicalmente. No entanto, ambos os sistemas de instrumento único e movimento reciprocante extruem menos bactérias apicalmente do que o sistema rotatório multi-instrumentos de referência.

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Os rios em todo o mundo estão ameaçados através da alteração do uso e cobertura do solo. Nesse contexto, o perifíton é sugerido como indicador biológico devido ao seu ciclo de vida curto, à comunidade autótrofa e à riqueza de espécies. O objetivo deste estudo foi identificar mudanças em parâmetros estruturais e funcionais da assembleia perifitica em relação aos diferentes tipos de cobertura do solo (pristino, perturbação intermediária e perturbado); em especial na limitação nutricional, crescimento e acúmulo, composição taxonômica e estequiometria da comunidade. O trabalho foi desenvolvido em três rios (Santa Maria, Itaperiti, Anil) da bacia Guapi-Macacu, RJ, Brasil. A limitação nutricional foi acessada através de Substratos Difusores de Nutrientes alocados in situ; estes substratos consistem em potes com agar-agar, enriquecidos com nutrientes (N, P, N+P), ou não (controle), que difundem até o filtro, servindo de substrato para o crescimento perifítico. Ainda, o crescimento foi acessado através da colonização de azulejos, amostrados em datas diferentes; na última data, a amostragem também foi feita para a verificação da composição taxonômica e estequiométrica da assembleia. Os resultados mostraram que a comunidade perifítica é limitada primariamente por luz nos pontos pristinos; já nos pontos perturbados, há limitação por nitrogênio ou fósforo, dependendo do uso do solo predominante agricultura com maior aporte de nitrogênio, causando limitação por fósforo, e pecuária com maior aporte de fósforo, causando limitação por nitrogênio. Os trechos perturbados apresentaram maior biomassa perifítica em termos de clorofila a; além disso, também mostraram as maiores taxas de crescimento da comunidade. Também, houve mudanças na composição taxonômica da comunidade no gradiente de perturbação, com o aumento de gêneros tolerantes à poluição e diminuição de gêneros não tolerantes e da diversidade e a equitabilidade. A intensidade luminosa foi determinante na presença dos táxons, e a concentração de fosfato, nas suas abundâncias. Por fim, as razões estequiométricas - C:N, C:P and N:P - diminuíram em função da concentração de nutrientes na água, indicando o potencial de remoção de nutrientes em córregos poluídos. O presente trabalho foi inovador na área limnológica devido à abordagem estequiométrica em conjunto com o grande número de outras variáveis biológicas. Em tempo, a dificuldade de separação dos efeitos das variáveis ambientais neste estudo in situ faz com que seja sugerido o uso de experimentos controlados em mesocosmos posteriormente

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Este trabalho tem como escopo analisar e delimitar o conceito, espécies, requisitos e consequências da revisibilidade das licenças ambientais. Não raras vezes, empreendedores, administradores públicos, juízes e todos os demais operadores do direito se veem em situações que contrapõem a estabilidade das relações jurídicas e a confiança legítima do comportamento estatal à necessidade de proteger o meio ambiente equilibrado para as presentes e futuras gerações. A revisão de licenças ambientais ainda vigentes é exatamente um dos campos onde essa análise tem espaço. Seja em circunstâncias provisórias ou definitivas, seja advinda de uma nulidade anterior ou de um fato ulterior, em determinadas hipóteses a iminência de dano ambiental faz com que o poder público não possa esperar o término da vigência do ato autorizativo para agir. Ao longo do texto, fixam-se as premissas para examinar cinco espécies de revisão: suspensão, modificação, cassação, invalidação e revogação das licenças ambientais, todas orientadas por algumas ideias comuns, mas cada uma delas com suas especificidades. Apresentam-se, outrossim, alguns contrapontos ao cabimento dessas medidas, notadamente a garantia constitucional de proteção do direito adquirido, não como objeção indiscriminada à atuação estatal, mas como forma de limitação dessa nos estreitos contornos traçados pelos princípios envolvidos. Ao final, trata-se também das consequências que podem advir desse ato revisor, em especial no que tange ao eventual cabimento de indenização ao empreendedor por ele afetado.

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This is the report from the Lune, Wyre and Furness Fisheries Advisory Committee meeting, which was held on the 4th April, 1977. The report contains information on byelaws, net limitation on the River Lune, Goosanders and Mergansers which concentrates on predation issues of these birds groups upon young salmonids, fisheries income and expenditure and fisheries activities. The section on fisheries activities includes an update on Middleton Hatchery; fishing conditions; and fisheries improvement work on the River Leven. The Fisheries Advisory Committee was part of the Regional Water Authorities, in this case the North West Water Authority. This preceded the Environment Agency which came into existence in 1996.

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This is the report from the Lune, Wyre and Furness Fisheries Advisory Committee meeting, which was held on the 25th October, 1976. The report contains sections on fish stocking, the drought situation, a net limitation order, fisheries activities, fish mortalities in the River Condor, and perch mortalities in Lake Windermere. The section on fish stocking includes background information about fish stocking by the authority; difficulties; migratory fish; non-migratory Trout and Coarse fish; stocking after pollution; stocking of Waters within the Region; stocking with coarse fish; and recommendations. The section on fisheries activities includes information on Middleton Hatchery; fish monitoring; fish mortalities; operation of Newby Bridge Sluice and drought conditions. The Fisheries Advisory Committee was part of the Regional Water Authorities, in this case the North West Water Authority. This preceded the Environment Agency which came into existence in 1996.

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This is the report from the Lune, Wyre and Furness Fisheries Advisory Committee meeting, which was held on the 15th January, 1979. It covers information on the proposed net limitation order and new fishery byelaws for the Rivers Lune and Wyre, the proposed byelaws for Skerton Weir, issues with the electric fish diversion screens for the Lune and the Wyre, and the monitoring of levels of radioactivity in migratory fish. The section on the report by the area fisheries officer on fishing activities includes river conditions and fishing for the Lune, Wyre and Furness and figures for migratory fish counted at Haverthwaite on the River Leven, Broadraine, Forge Weir and Skerton Weir on the River Lune and Duddon Hall. Also included is an update on Middleton Hatchery, fish disease, fish mortalities and net catch figures for 1978 of grilse, salmon and sea trout for the Lune, Kent, Leven and Duddon. The Fisheries Advisory Committee was part of the Regional Water Authorities, in this case the North West Water Authority. This preceded the Environment Agency which came into existence in 1996.

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This is the report from the Lune, Wyre and Furness Fisheries Advisory Committee meeting, which was held on the 9th April, 1979. It includes the River Leven and River Crake catchment study report, information on the match fishing experiment at Skerton Fishery, and the proposed net limitation order and fishery byelaws for the Lune and Wyre. Also covered is the report by the area fisheries officer on fisheries activities which comments on river conditions and fishing, migratory fish movements and fish spawning and an update on Middleton hatchery which gives the total number of ova laid down in the hatchery. It also gives numbers of brown trout stocked in the River Kent and it gives the data of monthly salmon and migratory trout catches on rod and line for the 1978 season. The Fisheries Advisory Committee was part of the Regional Water Authorities, in this case the North West Water Authority. This preceded the Environment Agency which came into existence in 1996.

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This is the report from the Lune, Wyre and Furness Fisheries Advisory Committee meeting, which was held on the 11th October 1979. The report contains the minutes of the last meeting along with the minutes of the Regional Fisheries Advisory Committee meeting held on 12th July 1979, information on pollution and fish mortalities in the River Conder, and net limitation order and fisheries byelaws for the River Lune and Wyre. It also includes the report by the area fisheries officer which looks at river conditions and fishing in the Rivers Lune, Furness and Wyre, fish monitoring at Forge Weir, Broadraine and Skerton Weir stations, and an update on Middleton Hatchery. Also covered is the cage rearing of smolts for the River Leven, stocking by the Water Authority and Angling Associations, fish mortalities and biological work carried out at Barrow Steel Works. The Fisheries Advisory Committee was part of the Regional Water Authorities, in this case the North West Water Authority. This preceded the Environment Agency which came into existence in 1996.

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This is the report from the Northern Area Fisheries Advisory Committee meeting, which was held on the 5th January, 1981. It covers information on the review of fisheries byelaws, netting off Flimby Beach and the review of a net limitation order which was due to expire. It also includes the report by the area fisheries officer on fisheries activities which comments on river conditions and fishing for salmon, sea trout and brown trout, and the recorded numbers of fish which passed through Yearl Weir fish counter up to the 9th November. Also covered in the report is an update on Holmwrangle hatchery and the stocking numbers of salmon, sea trout and non migratory trout by the Water Authority. Finally the report adds about fish disease, biological work and the considerations of the River Caldew as a migratory fish river. The Fisheries Advisory Committee was part of the Regional Water Authorities, in this case the North West Water Authority. This preceded the Environment Agency which came into existence in 1996.

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This is the report from the Central Area Fisheries Advisory Committee meeting, which was held on the 8th January, 1981. It covers information on the review of fisheries byelaws, netting off Flimby beach, a large fish mortality in the River Calder and Ribble, and the review of a net limitation order which was due to expire. It also includes the stocking of Worthington Lakes, Rivington Group Reservoirs and the River Wyre, the update on the proposals for the development of angling at Stocks Reservoir and the report by the area fisheries officer on fisheries activities. This comments on river conditions and fishing for salmon, sea trout and brown trout, and migratory fish movement. Also covered in the report is an update on Middleton Hatchery, salmon cages in the River Leven, Langcliffe Hatchery and the pilot hatchery, and stocking numbers of coarse fish and non migratory trout by the Angling Associations. Finally the report adds about fish mortalities, fish disease, poaching and management work. The Fisheries Advisory Committee was part of the Regional Water Authorities, in this case the North West Water Authority. This preceded the Environment Agency which came into existence in 1996.

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This is the report from the Lune, Wyre and Furness Fisheries Advisory Committee meeting, which was held on the 13th December 1979. The report contains the minutes of the last meeting along with the minutes of the Regional Fisheries Advisory Committee held on 12th November 1979. It also includes net limitation order and fisheries byelaws for the River Lune and River Wyre. The Fisheries Advisory Committee was part of the Regional Water Authorities, in this case the North West Water Authority. This preceded the Environment Agency which came into existence in 1996.

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This is the report from the Regional Fisheries Advisory Committee meeting, which was held on the 4th February 1980. The report contains the minutes of the Local Fisheries Advisory Committees, net and fixed engine licence duties, net limitation order for the River Lune and River Wyre and fishery byelaws for the River Lune. The Fisheries Advisory Committee was part of the Regional Water Authorities, in this case the North West Water Authority. This preceded the Environment Agency which came into existence in 1996.

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This is the report from the Northern Area Fisheries Advisory Committee meeting, which was held on the 29th March, 1982. It includes information on the Cumbrian Coastal Waters Net Limitation order, and the report by the area fisheries officer on fisheries activites from September 1981 to January 1982. The report covers information on river conditions and fishing, migratory fish movement, an update on the work at Holmwrangle Hatchery, fish disease, management and survey work and monthly salmon and sea trout catches for rod, line, nets and fixed engines for the 1981 season. The Fisheries Advisory Committee was part of the Regional Water Authorities, in this case the North West Water Authority. This preceded the Environment Agency which came into existence in 1996.

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This is the report from the Regional Fisheries Advisory Committee meeting, which was held on the 31st January, 1983. The report contains sections on Draft net licences (Rivers Derwent and Ellen estuaries), net limitation order, proposed pike ranching scheme on Esthwaite Water, Diseases of fish bill, outbreak of Whirling disease, and the control of federal mink. The Fisheries Advisory Committee was part of the Regional Water Authorities, in this case the North West Water Authority. This preceded the Environment Agency which came into existence in 1996.