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Provedor de dados:  RChHN
País:  Chile
Título:  Paleolimnological studies of Laguna Chica of San Pedro (VIII Region): Diatoms, hydrocarbons and fatty acid records
Autores:  URRUTIA,ROBERTO
KOEN,SABBE
CRUCES,FABIOLA
POZO,KARLA
BECERRA,JOSE
ARANEDA,ALBERTO
VYVERMAN,WIM
PARRA,OSCAR
Data:  2000-12-01
Ano:  2000
Palavras-chave:  Diatoms
Hydrocarbons
Fatty acids
Paleolimnology
Land use
Resumo:  Diatom, hydrocarbons and fatty acid sedimentary records were used for reconstructing the recent (last 150 years) palaeolimnological history of Laguna Chica of San Pedro (Concepción, VIII Región, Chile). Cluster analyses (Constrained Incremental Sum of Squares) on the diatom data revealed three distinct periods. The first period (1883-1940's) showed a pronounced increase in sedimentation rate and a slight increase in organic matter accumulation. In this period, eutrophic species (Aulacoseira granulata and Staurosira construens) became increasingly dominant. From the 1940s until the 1970s the diatom signal is more equivocal: after the initial decrease in the relative abundance of A. granulata and S. construens their numbers fluctuate without a clear pattern. Sedimentation rates strongly fluctuate in this period. From 1978 onwards eutrophic species are in decline while indicators of oligotrophic conditions, such as Cyclotella stelligera and Aulacoseira distans, become more abundant. This shift in the lake trophic status could not be attributed to a reduction in the nutrient load from the catchment and we hypothesize that the invasion of the lake by the submersed macrophyte Egeria densa has altered nutrient availability to the plankton communities. This is in agreement with the hydrocarbons and fatty acid analyses which demonstrate a shift in carbon number distributions from short chain alkanes and alkanoic acids (typical for microalgae) to long chain molecules (characteristic for higher plants) in the upper layers of the lake sediment
Tipo:  Journal article
Idioma:  Inglês
Identificador:  http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2000000400014
Editor:  Sociedad de Biología de Chile
Formato:  text/html
Fonte:  Revista chilena de historia natural v.73 n.4 2000
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