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Meandering Cutoff Reshapes the Trophic Characteristics of Macroinvertebrates in the Upper Yellow River Basin

Author(s): Xiongdong Zhou; Mengzhen Xu; Zhaoyin Wang; Jiahao Zhang; Congcong Wang

Linked Author(s): Zhaoyin Wang

Keywords: No keywords

Abstract: Meandering is one of the most common river patterns all over the world. Due to the meandering cutoff, river channels are abandoned, and form into oxbow lakes, which are the typical lentic habitats distinguished from lotic main channels. The compositional changes in macroinvertebrates in response to the meandering cutoff have been widely investigated. However, how this fluvial process influences the trophic characteristics of macroinvertebrates remains unclear. In this study, we surveyed 29 patches in the Bai River on the Qinghai-Tibet Plateau, and categorized them into four types of habitats, namely sand-bed river habitat (SA), cobble-bed river habitat (CB), plesiopotamal oxbow habitat (OI), and paleopotamal oxbow habitat (OII), according to the environmental conditions. For each type of habitat, a representative food web of macroinvertebrates was constructed, and the carbon storage as well as flux in the food web was estimated based on the biomass balance model. Our results showed that oxbow habitats (OI, 125 mg·m-2; and OII, 213 mg·m-2) not only possessed much higher carbon storages than river habitats (SA, 4 mg·m-2; and CB, 63 mg·m-2), but also provided more carbon fluxes (OI, OII, SA, and CB: 347,762,10, and 158 mg·m-2·yr-1, respectively). Hydrological connectivity variations, as results of meandering fluvial process, played important roles in influencing trophic characteristics of macroinvertebrates -- as the oxbow less connected to the main channel, the food web became better structured and more stable, and the carbon storage and flux accordingly increased. This study revealed the significance of natural meandering cutoff in improving the floodplain ecology on the high plateau area from the trophic perspectives.

DOI:

Year: 2022

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