47 resultados para simultaneous publication

em Plymouth Marine Science Electronic Archive (PlyMSEA)


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The use of a Leslie matrix for analysis of a population normally implies that the age structure of the population is known. However, this restriction can be overcome if the population can be partitioned into recognisably different stages, and some information on stage duration and fecundity is available, in which case the age structure may be determined by the analysis itself. As an example of this approach we consider the estimation of the mortality rate applying to a population from a sequence of observed stage frequency vectors. The technique does not require that the population has attained a stable age structure nor that distinct cohorts can be recognised.

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The rationale behind the use of analyses of estuarine organisms to assess levels of heavy-metal contamination is described and compared with alternative methods such as the analysis of waters or sediments. Based on field observations in United Kingdom estuaries and on evidence from the literature, an assessment is made of the suitability of 17 species as the indicators of metals and metalloids including Ag, As, Cd, Co, Cr, Cu, Hg, Ni, Se, Sn, Pb and Zn.

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A 64-page catalogue of material in the MBA Archive Collection containing details of documents, records, and personal papers relating to the history and development of the Marine Biological Association.

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The use of the deposit-feeding molluscs Scrobicularia plana and Macoma balthica and the burrowing polychaete Nereis diversicolor as indicators of the biological availability of heavy metals in sediments has been evaluated. Concentrations of Ag, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Sn and Zn have been measured in organisms and sediments from more than 30 estuaries in south west England and South Wales and indicate that the biological availability of most metals varies by order of magnitude between uncontaminated and contaminated sites. The results have been compared with those obtained with the use of other species of indicator organisms in estuaries.