engleski

Colonization of Achnanthes species in periphyton, the Ombla estuary (eastern Adriatic Sea, Croatia)

Colonization of periphytic diatoms on artificial substrates (Plexiglas) was analyzed in the relatively deep and highly stratified oligotrophic Ombla Estuary, southern Adriatic, during July 2006. Samples were taken at 0.2, 0.5, 1.2, 1.5, 3.0 and 3.3 m, on weekly basis. Diatom abundance increased during colonisation, and decreased with depth. Maximum of 8.2 × 10^6 cells/cm^2 was detected in the 0.2– 0.5 layer after two weeks of incubation. Diatom assemblage dominated by species of Achnanthes (nine species and two varieties). Among them, Achnanthes brevipes var. brevipes, Achnanthes brevipes var. intermedia and Achnanthes parvula were detected most frequently (100%), and abundance of A. brevipes and A. parvula increased up to 295 × 10^3 cells/cm^2 at 0.5 m depth after four weeks. Cluster and Principal Component Analysis were performed to display physical and chemical parameters which favoured diatom development. Differences among cell size, valve structure and environmental conditions were correlated.

Diatoms; Achnanthes; artificial substrates; Ombla estuary; Adriatic Sea

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