Adrian, R. Institut fuer Gewaesseroekologie und Binnenfischerei, adrian@igb-berlin.de
Schneider, B. Institut fuer Gewaesseroekologie und Binnenfischerei, schneider@igb-berlin.de

 
THE ROLE OF COPEPODS AND CLADOCERANS IN STRUCTURING MICROBIAL FOOD WEBS
 
We examined the individual effects of Eudiaptomus graciloides (adults, copepodites, nauplii), Diacyclops, Thermocyclops and Daphnia as compared to the entire crustacean community on the growth rates of the spring microbial community (April - June) of a mesotrophic lake (Großer Vätersee, Germany). Calanoid (adults and juveniles) and cyclopoid copepods as well as Daphnia exhibited always higher negative effects on ciliates in the larger size category (20-55 µm, mostly >75%) as compared to ciliates in the 10-20 µm size range. Overall, adult E. graciloides had the strongest negative effect on ciliates, followed by late copepodite stages of E. graciloides and adult cyclopoid copepods, which had similar effects. Daphnia had the weakest effect on the ciliate community. Growth rates of heterotrophic nanoflagellates (HNF) and autotrophic picoplankton (APP) communities were usually not affected by E. graciloides (adults and copepodites). For cyclopoid copepods effects were species specific, while clear negative effects on HNF and APP were observed for Daphnia. Since grazing rates on phytoplankton (Chl. a) were rather low, respectively not detectable at all, the microbial community is likely to play an important role in their diet at times of low phytoplankton biomass (1-2µg/L).
 
Day: Wednesday, Feb. 3
Time: 10:45 - 11:00am
Location: Hilton of Santa Fe
 
Code: CS60WE1045H