Airborne microeukaryote colonists in experimental water containers: diversity, succession, life histories and established food webs

Abstract

Airborne freshwater and marine microeukaryotes in the city of Thessaloniki, situated in Thermaikos Bay, Greece, were examined as sources of colonization of experimental water containers during the period autumn 2007 to spring 2008. The microeukaryote composition of the plankton in the nearby aquatic systems (distance < 1 km) was also examined. Airborne microeukaryotes were examined by morphology and 18S rRNA gene diversity. A total of 29 species of airborne microeukaryotes were identified, most of them commonly observed in aerobiological studies. Airborne organisms of only 8 taxa were also detected in the nearby aquatic systems. The algae Haematococcus lacustris, a Chlorella-like taxon, and Scenedesmus cf. obliquus, the heterotrophic nanoflagellates (HNF) Bodo sp., Cafeteria minuta and Rynchomonas nasuta, and the ciliate Pattersoniella vitiphila were present in all 3 seasons, indicating capabilities of successful dispersal and colonization under a wide range of meteorological conditions. Rapid colonization of the water containers by the microeukaryotes occurred at the beginning of the experiment, but the rate of colonization quickly stabilized. The initial phase of colonization was dominated by HNF; subsequently, members of the Chlorophyta were the dominant autotrophs. The heterotrophic and autotrophic colonists established similar food webs in all 3 seasons, with P. vitiphila being the common top predator.