Fidelidad de ensambles de diatomeas actuales en sedimentos estuáricos del sudeste bonaerense.

HASSAN, G.S., ESPINOSA, M.A. E ISLA, F.I.

Puerto Madryn

Simposio; Reunión Anual de Comunicaciones y Simposio del 50º Aniversario de la APA.; 2005

APA

In order to evaluate how accurately diatom thanatocoenoses preserve the environmental information stored in the biocenosis, the environmental fidelity of dead diatom assemblages along two microtidal estuarine systems from the southeastern Buenos Aires province (Argentina) is quantitatively and qualitatively analyzed. Living communities (inferred from countings of protoplasm containing cells) are compared to dead diatom assemblages through several fidelity metrics. Gradient analysis (Canonical Correspondence Analyses) is applied in order to assess the quantitative relation between diatom assemblages and the salinity gradient, and the presence of allochthonous components on diatom assemblages is assessed by analyzing the distribution of the main ecological diatom groups. Results suggest a good agreement between living communities and total assemblages in surface sediments from both estuaries. Although a mixture of allochthonous and autochthonous diatoms does occur, a high percentage of the variance in diatom assemblages composition is explained by the salinity gradient, indicating that taphonomic alterations play a minor role in structuring these assemblages. The good preservation of diatom thanatocoenoses in estuarine sediments make them accurate indicators of the environmental conditions at the point of deposition, providing useful information for paleosalinity reconstructions in coastal settings.