Microalgae in Ecology: Ecosystem Functioning Experiments

Ecosystem functioning is one of the most striking topics in ecological research. All human beings depend on the functioning of ecosystems and the services provided by ecosystems [1]. Ecosystem services provide food from e.g. agriculture and fish as well as clean water and air. Thus, the functioning of ecosystems is a crucial topic of experimental studies in ecology. The first known ecological experiment was on increases of biomass in mixed cultures of grasses compared to monocultures of the species [2,3]. Although, this experiment gave an empirical evidence of positive effects of species richness on biomass production [2] similar experiments were repeated in the 20th century and finally a series of meta-analyses was necessary to reach a consensus about positive biodiversity-ecosystem functioning effects, i.e., biodiversity effects [4-7]. Most of these manipulation experiments observing biodiversity effects on ecosystem functioning were conducted in grassland ecosystems or with grassland species [6,7]. This surprises not because terrestrial ecosystems are of high commercial interest [8,9]. However, aquatic ecosystems provide about half of global net primary production [10]. The understanding of the processes underlying the ecosystem functioning of aquatic systems and the impact of global change is far beyond our understanding of the terrestrial systems [11,12]. As results from terrestrial systems cannot be transferred directly to aquatic systems [13], studies on the functioning of aquatic ecosystems are required.