Toxicity, autecology and DNA content in the marine flagellate Pseudochattonella (Dictyochophyceae, Heterokonta)

Abstract

Phytoplankton is main producers of marine pelagic food webs, acting as link between the energy source, the sun, and consumers. Phytoplankton is an evolutionary diverse group whick is, however, traditionally assembled due to their ability to fix carbon through photosynthesis.

Some phytoplankton taxa occur in a form of algal blooms that may cause problems for their environment. This phenomenon is often associated with the name harmful algal bloom (HAB) and it has important economical and health related implications. The ichthyotoxic genus Pseudochattonella, investigated in this thesis, is such taxon that can produce HAB. Primary goal of this work was to investigate mechanisms of the toxicity of Pseudochattonella and deliver a proper assay for detecting harmful effects in ichthyotoxic flagellates.

There are increasing interests for utilizing algae in topics like toxicity assays, biodiesel production, as food components and for medical usage. A new-developed assay for estimating optimal environmental conditions for growth, loss rates and compensation irradiance was carried out in microplates. Furthermore, the assay was used for comparisons of seven strains from the two known species of Pseudochattonella.

DNA content of organisms is strongly correlated with cell volume, nuclear volume, growth rates and cell cycle length. However, closely related taxa might have large differences in genome size. Two species of Pseudochattonella and several strains of these species were compared in respect of their genome size.