Fish communities in rivers to be affected by Roadford Reservoir

This is the Fish communities in rivers to be affected by Roadford Reservoir report produced by South West Water Authority in 1978. Surveys were carried, out on the Rivers Wolf, Thrushel, Lew and Lumburn, which are likely to be affected directly and indirectly by the construction and use of Roadford Reservoir. Of the upper reaches of three rivers to be affected directly by water releases, two were found to support abundant stocks of salmon and trout, and the third was found to contain abundant stocks of trout and eels. The River Thrushel will be affected indirectly and in this river salmon and trout stocks were present in slightly lower abundance than in others. Population estimates, densities, mean lengths and approximate biomass values were calculated. Other species were present in all rivers, usually in great abundance.

Fisheries survey of the River Otter 1978

This is the Fisheries survey of the River Otter report produced by South West Water Authority in 1979. This report focuses on the trout fishery in the River Otter and the possible effects of abstraction and/or pollution. A survey was carried out to describe the fish stocks. Trout and eels were the dominant species. The population structure of trout was peculiar, there being relatively few juveniles. Growth was good and there were numerous trout of take able size in the river at the end of the fishing season. Variations in the parameters measured are explained and nothing can be attributed to abstraction or pollution.

Análise multielementar em peças de ouro antigo utilizando fluorescência de raios X por dispersão em energia

Os métodos de análise não destrutiva vêm sendo largamente empregados na área de Arqueometria. Estes métodos analisam artefatos históricos e obras de arte fornecendo informações da composição, das técnicas utilizadas e do local de manufatura da época. Assim, é possível fazer a datação, estabelecer a autenticidade e avaliar técnicas de conservação e restauração. A Fluorescência de Raios X por Dispersão de Energia (EDXRF) é um método que permite fazer análises quantitativas e qualitativas multielementares dos artefatos de forma não destrutiva. Neste estudo foram analisados artefatos compostos por ouro de diferentes épocas através da técnica de Fluorescência de Raios X por Dispersão em Energia (EDXRF). Dentre os artefatos, encontram-se brincos, pingentes, estatuetas e adornos de roupa cedidos pelo Instituto de Pesquisa Histórica e Arqueológica do Rio de Janeiro (IPHARJ). As análises foram realizadas através do sistema comercial ARTAX 200. Este sistema possui ânodo de Molibdênio. Foi utilizado um filtro de alumínio com 315 μm de espessura e foi operado em 40 kV, 250 μA com 300 s de aquisição. As concentrações de Cu, Au e Ag foram obtidas através da curva de calibração feita com padrões de ouro de 24k, 18k, 16k, 14k, 12k e 10k. Os resultados mostram que todas as peças contêm ligas metálicas e ouro em diferentes concentrações em sua composição. A partir das diferenças nas concentrações de ouro, foi possível classificar as peças quanto à pureza do ouro (quilatagem). Além disso, foi possível estimar a época em que estas peças foram manufaturadas a partir da comparação dos resultados encontrados com aqueles encontrados na literatura.

Year-to-year changes of vertical temperature distribution in the California Current region: 1954 to 1986

Studies by Enfield and Allen (1980), McLain et al (1985), and others have shown that anomalously warm years in the northern coastal California Current correspond to El Niño conditions in the equatorial Pacific Ocean. Ocean model studies suggest a mechanical link between the northern coastal California Current and the equatorial ocean through long waves that propagate cyclonically along the ocean boundary (McCreary 1976; Clarke 1983; Shriver et al 1991). However, distinct observational evidence of such an oceanic connection is not extensive. Much of the supposed El Niño variation in temperature and sea level data from the coastal California Current region can be associated with the effects of anomalously intense north Pacific atmospheric cyclogenesis, which is frequently augmented during El Niño years (Wallace and Gutzler 1981; Simpson 1983; Emery and Hamilton 1984). This study uses time series of ocean temperature data to distinguish between locally forced effects, initiated by north Pacific atmospheric changes, and remotely forced effects, initiated by equatorial Pacific atmospheric changes related to El Niño events.

Effects of periphyton grown on bamboo substrates on growth and production of Indian major carp, rohu (Label rohita Ham.)

The effects of periphyton, grown on bamboo substrates, on growth and production of Indian major carp, rohu, Labeo rohita (Hamilton), were studied in 10 ponds during July to October '95 at the Bangladesh Agricultural University, Mymensingh. Five ponds were provided with bamboo substrates (treatment I) and the rests without bamboo substrates (treatment II). It was revealed that there had been no discernible difference in the water quality parameters between treatments. A large number of plankton (30 genera) showed periphytic nature and colonized on the bamboo substrates. The growth and production of fish was significantly (p<0.05) higher in the ponds with bamboo substrates as compared to the ponds without substrates. The net production of rohu in treatment I was about 1.7 times higher than that of treatment II. Fish production was as much as 1899 kg/ha over a culture period of 4 months in the periphyton-based production system.

Acute toxicity of chlorpyrifos, cadusafos and diazinon to three Indian major carps (Catla catla, Labeo rohita and Cirrhinus mrigala) fingerlings

Fingerlings of three Indian major carps, viz. Catla catla (Hamilton-Buchanon), Labeo rohita (Hamilton-Buchanon) and Cirrhinus mrigala (Hamilton-Buchanon), were exposed to different concentrations of chlorpyrifos (lorsban 10 G), cadusafos (rugby 10 G) and diazinon (basudin 10 G) for a period of 96h with a view to determine the median lethal concentrations (LC sub50) values for each of chemicals. Of the tested concentrations, chlorpyrifos at a dose of 6.65 ppm, cadusafos at 2.0 ppm and diazinon at a dose of 8.40 ppm or above induced 100% mortalities within 96h of exposure. The 96h LC sub50 values of chlorpyrefos, cadusafos and diazinon were 1.66, 0.72 and 2.10 ppm for C. catla, 2.35, 0.72 and 2.97 for L. rohita and 2.35, 0.72 and 2.10 ppm for C. mrigala, respectively. Pesticide induced behavioral abnormalities observed in the present study included erratic movements, rapid operculum activities, jumping of fish out of the test media, violent spasm and convulsion.