Consulta: subjectFacets:"Time trends"
Registros recuperados: 2
Data/hora: 20/05/2024 03:05:13

Do survey design and wind conditions influence survey indices ?
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Poulard, Jean-charles; Trenkel, Verena.
Survey indices play an important role in stock assessments as they provide information on stock trends. In certain cases large interannual variations have been observed which are unlikely to reflect true underlying stock changes but are rather outliers. When survey indices for several species appear to be outliers for the same year, the suspicion is raised that something happened during the survey of that year. This is called a year-effect in survey catches. To study the potential year-effect in survey catches for the French autumn groundfish survey taking place in the Bay of Biscay, several indicators for survey design and wind conditions were derived as explanatory variables and Principal Component Analysis was used to study the relationship between...
Tipo: Text
Palavras-chave: Bay of Biscay; Survey conditions; Time trends; Catchability; Survey index.
Ano: 2007
URL: http://archimer.ifremer.fr/doc/2007/publication-2690.pdf

Retrospective study of metal contamination time trends in the French part of the Bay of Biscay
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Boutier, Bernard; Quintin, Jean-yves; Rozuel, Emmanuelle; Auger, Dominique; Bretaudeau-sanjuan, Jane.
Two cores were sampled in the Bay of Biscay: one a few miles off the Gironde estuary (pointe de la Coubre), the other near the Spanish border (Capbreton canyon) to study past variations in sediment contamination. Radiochronology (210Pb, 137Cs) and total metal determinations by ICP-MS allowed the study of time trends for metal concentrations in sediment. Off the Gironde, during the time interval recorded by the core (1958–1999), all metal concentrations remained less than OSPAR background values. Some variations occurred along the Cd and Zn profiles, which may correspond to a very attenuated signal from the Gironde outputs. This suggests that this area was not submitted to any significant anthropogenic input of metals between 1958 and 1999. In the canyon of...
Tipo: Text
Palavras-chave: Sediment; Metal contamination; Dating; Cores; Time trends.
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00061/17254/16094.pdf