Periodic Reporting for period 1 - CHRYSOWEB (The effect of mixotrophic chrysophytes on secondary productivity in pelagic food webs)
Reporting period: 2016-02-01 to 2018-01-31
The aim of CHRYSOWEB was to specifically address the consequences of the increasing share of golden algae for consumers in lake food webs. To this end, we applied an integrative approach (laboratory experiments, field observations, biochemical analyses) to get a comprehensive understanding of this key group on aquatic ecosystem functioning.
By using an array of chrysophyte species as food, we found multiple effects on zooplankton, which were generally negative compared to a high-quality reference food. The mechanisms include feeding inhibition, nutritional deficiency and toxicity. The results of CHRYSOWEB imply that the dominance of chrysophytes is able to significantly alter zooplankton secondary production and community composition, and therefore energy flow in aquatic food webs.
The nutritional quality of chrysophytes was found to be intermediate to detrimental for zooplankton. The responses of different higher taxa of zooplankton to chrysophyte diet varied considerably. Water fleas (cladocerans) were especially sensitive to blooms of large colonial algae, which reduced their food uptake by physical interference, while copepods were more successful in handling them. On the other hand, copepods seem to be more sensitive to food quality, being unable to reach adult stage on any golden algae we provided as food. Based on short-term toxicity tests, however, only a few chrysophyte species proved to be toxic, implying that negative effects generally lie in their low nutritional value, which was furthermore supported by their biochemical composition.
The results of CHRYSOWEB were communicated to the wide scientific community at international conferences, including the ASLO Aquatic Sciences Meeting, which is the largest meeting of researchers in aquatic sciences. Press releases were published to inform the broader public about the project, including an article in ‘Der Standard’, which is one of the largest daily newspapers in Austria. The results were also disseminated to Austrian and international university students with different backgrounds in forms of seminars and lectures. The results provide a basis for at least three separate papers, which will be submitted to leading journals in limnology and ecology (publications expected in 2018/2019). Besides, the results of CHRYSOWEB will provide a basis for a master thesis (Claudia Schneider, University of Vienna).
The project provided an excellent training to Dr Vad, with several opportunities to improve his skills both conceptually and methodologically. He was well-integrated in a highly international research team, allowing him to expand his scientific network. He showed great capacity to work independently, performing the task and project management largely on its own. Furthermore, he was a co-supervisor of a master student and a number of trainees, which greatly improved his leadership skills. CHRYSOWEB has undoubtedly contributed to the development of his scientific independence.
The topic of CRYSOWEB is timely and novel and therefore, the results have a great potential for higher education. They were already used at university lectures and seminars, and will be used in the future as well.