The fate of cyanobacterial detritus in the food web of Lake Taihu: a mesocosm study using 13C and 15N labeling

• Published in: Hydrobiologia 2013-06, Vol.710 (1), p.39-46
• Main Authors: Yu, Jinlei, Li, Yanmin, Liu, Xiaoling, Li, Kuanyi, Chen, Feizhou, Gulati, Ramesh, Liu, Zhengwen
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Biomedical and Life Sciences; Ecology; Freshwater & Marine Ecology; Fundamental and applied biological sciences. Psychology; General aspects; Life Sciences; Shallow Lake Ecosystems; Synecology; Zoology
• ISSN: 0018-8158; 1573-5117
• DOI: 10.1007/s10750-012-1205-y

The ecosystem of the highly eutrophic Lake Taihu (China) is seriously affected by recurrent cyanobacterial blooms, but little is known about the contribution made by cyanobacteria to the food web. In this study, we investigated the fate of detritus of the cyanobacterium Microcystis in the food web of Lake Taihu through a 19-day mesocosm experiment using stable-isotopic tracers of carbon ( 13 C) and nitrogen ( 15 N). 13 C- and 15 N-labeled Microcystis detritus was added to the mesocosm tanks and tracked through different elements of the food web. We found clear enrichment with both 13 C and 15 N in some zooplankton species, including Daphnia , Diaphanosoma , and Sinocalanus , which suggests that these zooplankters can utilize cyanobacterial detritus as a food source. Benthic animals, chironomid larvae and Limnodrilus , also showed pronounced increases in 13 C and 15 N, but the isotope increase was relatively smaller in the gastropods, Radix sp. and Bellamya sp., implying that they either exploited this food source differently or responded slower than the zooplankton, which apparently grew faster than the snails. Our study suggests that cyanobacterial detritus, originating almost wholly from the bloom-forming Microcystis , is an important food source for both planktonic and benthic food webs in eutrophic lakes such as Lake Taihu.