Effects of warming and nutrients on the microbial food web in shallowlake mesocosms

• Published in: European Journal of Protistology
• Main Authors: Zingel, Priit, Cremona, Fabien, Nõges, Tiina, Cao, Yu, Neif, Érika M., Coppens, Jan, Işkın, Uğur, Lauridsen, Torben, Davidson, Thomas A., Søndergaard, Martin, Beklioglu, Meryem, Jeppesen, Erik
• Other Authors: Centre for Limnology. Institute of Agricultural and Environmental Sciences
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Elsevier 2018
• Subjects: bacteria; ciliates; global warming; heterotrophic flagellates; nutrients; articles; Arctic; Global warming
• Online Access: http://hdl.handle.net/10492/7845; https://doi.org/10.1016/j.ejop.2018.03.001

We analysed changes in the abundance, biomass and cell size of the microbial food web community (bacteria, heterotrophicnanoflagellates, ciliates) at contrasting nutrient concentrations and temperatures during a simulated heat wave. We used 24mesocosms mimicking shallow lakes in which two nutrient levels (unenriched and enriched by adding nitrogen and phosphorus)and three different temperature scenarios (ambient, IPCC A2 scenario and A2+) are simulated (4 replicates of each).Experiments using the mesocosms have been running un-interrupted since 2003. A 1-month heat wave was imitated by anextra 5◦C increase in the previously heated mesocosms (from 1st July to 1st August 2014). Changes in water temperatureinduced within a few days a strong effect on the microbial food web functioning, demonstrating a quick response of microbialcommunities to the changes in environment, due to their short generation times. Warming and nutrients showed synergisticeffects. Microbial assemblages of heterotrophic nanoflagellates and ciliates responded positively to the heating, the increasebeing largest in the enriched mesocosms. The results indicate that warming and nutrients in combination can set off complexinteractions in the microbial food web functioning. This work was supported by MARS project (ManagingAquatic ecosystems and water Resources under multipleStress, EU 7th Framework Programme, contract no.: 603378)and by institutional grant IUT 21-2 of the Estonian Min-istry of Education and Research. The Danish group wasalso supported by PROGNOS (Predicting in-lake RespOnsesto chanGe using Near real time mOdelS – Water JointProgramme Initiative) and AQUACOSM (Network of Lead-ing European AQUAtic MesoCOSM Facilities ConnectingMountains to Oceans from the Arctic to the Mediterranean),the latter also supporting the Turkish group. Yu Cao issupported by NSF-China (31500296) and CSC (The ChinaScholarship Council). This work was supported by MARS project (ManagingAquatic ecosystems and water Resources under multipleStress, EU 7th ...