Vortrag Elly Spijkerman

Hydrobiological Seminar 2019-11-07

https://tu-dresden.de/hydro/hyb-seminar

"Life in a deep chlorophyll maximum: sub-optimal?"

Dr. Elly Spijkerman
Landestalsperrenverwaltung des Freistaates Sachsen, Untersuchungsstelle Plauen
former affiliation: University Potsdam

In the deep, cooler layers of clear, nutrient-poor, stratified water bodies, phytoplankton often accumulate to form a thin band or "deep chlorophyll maximum" (DCM) of ecological importance. Under such conditions, these photosynthetic microorganisms may be close to their physiological compensation points and to the boundaries of their ecological tolerance. To grow and survive any resulting energy limitation, DCM species are thought to exhibit highly specialised or flexible acclimation strategies.

In my presentation, I present results from 2 studies in which a DCM is an important ecological habitat. The first study concerns Chlamydomonas acidophila: a motile, unicellular, phytoplanktonic flagellate that dominates the DCM in the stratified, acidic Lake 111. Here we performed physiological and behavioural responses in laboratory experiments and subsequently related those to field observations.

In the second study I show some data from the drinking water reservoir Dröda, where the filamentous cyanophyte Planktothrix rubescens accumulates in the DCM by regulating their gas vacuoles. Special care is taken here as the species produces potent hepatotoxins called microcystins.

The research on the ecophysiological complexity of DCM inhabitants enhances our understanding of lake ecology, resource cycles and food web interactions. In applied limnology its value lies in the prediction of the accumulation of ‘problematic’ phytoplankton species.