Planktonic fungi in lakes: Potential roles in pelagic food webs and development of molecular techniques for their study.
Recently, molecular surveys of the planktonic microeukaryotic community in freshwater lakes have revealed an unexpectedly high diversity of zoosporic fungi. However, the specific and functional diversity of planktonic fungi as well as their abundances and dynamics in lakes remain unknown, and fungi have never been taken into account in conceptual models of the pelagic microbial food webs.
In addition, due to their small size and shortage of distinct morphological features, fungal zoospores may have been misidentified as bacterivorous heterotrophic flagellates in previous studies. Thus, taking fungi into account in pelagic microbial food webs could strongly modify our perception of carbon flow in these systems. Because classical microscopic methods do not adequately distinguish species of zoosporic fungi, specific and sensitive methods for their detection and quantifcation need to be developed. Preliminary results indicate that molecular techniques such as cloning-sequencing and quantitative PCR are promising tools for the characterization of the planktonic fungal community.