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Aquatic Microbial Ecology

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AME 37:55-62 (2004)  -  doi:10.3354/ame037055

Abundance and dynamics of free flagellate scales in marine costal ecosystems

Harald Landa, Gunnar Bratbak, Mikal Heldal*

Department of Microbiology, University of Bergen, Jahnebakken 5, 5020 Bergen, Norway
*Corresponding author. Email:

ABSTRACT: Some groups of algae form extracellular scales of organic or inorganic material as part of their extracellular matrix, and such scales, shed from algae, are frequently observed by electron microscopy in marine water samples. However, virtually nothing is known about the production and fate of algal scales in natural ecosystems. In this study we demonstrate the seasonal variation of free scales in Norwegian coastal waters and their short time dynamics (3 wk) in enclosed water masses with artificially induced phytoplankton blooms. In addition we estimate decay rates of free scales under laboratory conditions. The total abundance of scales was 3 × 104 to 1.2 × 106 ml-1 in the coastal ecosystem we studied and we could follow the dynamics of free scales from different species of Pyramimonas, Heterocapsa and Chrysochromulina. From laboratory incubation we measured decay rates of free scales in the range of -0.01 to -0.02 d-1. The mechanism for disappearance of algal scales seems to be a combined effect of degradation and aggregation.

KEY WORDS: Microalgae · Scales · Transmission electron microscopy · TEM · Marine particles

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