engleski

MORPHOLOGY AND PHYLOGENY OF PICOEUKARYOTES AND PLANKTONIC PENNATE DIATOMS IN THE MIDDLE AND SOUTH ADRIATIC SEA

The smallest protists, generally called picoeukaryotes, and planktonic pennate diatoms have received limited attention in world oceans, although they are numerous and important for primary production, biogeochemical cycles and for carbon injection into the deep ocean. In this thesis, represented through seven scientific publications, cultivated planktonic pennate diatoms and picoeukaryotes were investigated with traditional methods (light and electron microscopy, morphometry) and with molecular analyses, including multi-gene phylogenies, and were identified as genera Entomoneis, Pseudo-nitzschia, Haslea and Picochlorum. Detailed investigations of genus Entomoneis resulted with description of seven new species. General picoeukaryotic diversity was addressed by eDNA amplicon sequencing V4 variable region of nuclear 18S rRNA gene. Obtained results identified 95% of the picoeukaryotic community as hetero- or mixotrophic, mostly belonging to parasitic dinoflagellates and radiolarians, while only 5% of the community was represented with photoautotrophic picoeukaryotes belonging to classes of green algae, haptophytes, stramenopiles and cryptophytes. One cultivated Picochlorum sp. strain was subjected to growth rate experiment and pigment and lipid analyses, resulting in interesting and promising data for future biotechnological studies.

picoeukaryotes, planktonic pennate diatoms, morphology, phylogeny

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