Application of subfossil Bosmina and its δ 13 C values in tracing the long-term food web dynamics of shallow eutrophic lakes: A case in Taihu Lake, southeast China

• Published in: The Science of the total environment 2020-04, Vol.730, p.138909
• Main Authors: Cheng, Longjuan, Kattel, Giri, Xue, Bin, Yao, Shuchun, Li, Lingling, Liu, Jinliang
• Format: Article
• Language: English
• ISSN: 1879-1026

Cladoceran subfossil assemblages have been used successfully to trace the signals of long-term changes in lake eutrophication. However, their potential for reconstructing food webs has not yet been explored extensively. Here, we assess whether the stable carbon isotope analysis (SCIA) of subfossil Bosmina can be used to reconstruct the eutrophication and food web history of a shallow lake in southeast China. Two Pb-dated sediment cores were collected from the western and central parts of Taihu Lake, one of the largest eutrophic lakes in the region. Multiproxy analyses of the cores were performed, including of the subfossil Bosmina assemblages, stable carbon isotopes of subfossil Bosmina (δ C ) and bulk sediment (δ C ), total organic carbon (TOC), loss on ignition (LOI), C/N, total nitrogen (TN), and total phosphorous (TP). Stable carbon isotopes of living algae (δ C ) and Bosmina (δ C ) were also measured at the same sampling locations. The δ C gradually declined over time with reciprocal increases in the assemblages of subfossil Bosmina and total cladocerans and in the TOC, LOI, TN and TP in both cores. The δ C and δ C values further revealed depleted C. The changes in the δ C in relation to the other proxies indicated rapid nutrient enrichment and a possible shift in the food web in Taihu Lake, providing new insight into the reconstruction of food webs and eutrophication in shallow lakes in southeast China.