Date

2020-07-20

Author

Shen, Ruijie
Gu, Xiaohong
Chen, Huihui
Mao, Zhigang
Zeng, Qingfei
Jeppesen, Erik

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In outdoor mesocosms, we experimentally studied the effect of combining two native filter feeders, bighead carp (Aristichthys nobilis) and Asian clam (Corbicula fluminea), to control nuisance cyanobacterial blooms. Four treatments - clam-only, fish-only, combined and controls - were used. In combination, bighead carp (80 g m(-3)) and Asian clam (260 g m(-2)), had a remarkable controlling effect on phytoplankton biomass and improved water quality. By the end of the experiment, the chlorophyll a (Chl a) concentration of the combined group was below 5 mu g L-1 compared with 36 mu g L-1 in the clam-only treatments and 31 mu g L-1 in the controls, whereas Chl a in the fish-only group had increased to 211 mu g L-1. Large-sized algae (Microcystis sp.) dominated in the control group and the clam-only group, whereas small-sized algae (Actinastrum hantzschii and Clamydomonas globose) dominated in the fish-only group. The concentrations of total nitrogen (TN) and total phosphorus (TP) in the water column were significantly reduced by clam stocking, regardless of the presence of fish. A 24-h laboratory experiment was conducted to verify whether the excrements produced by clams filtering small-sized algae could be eaten by bighead carp. At the end of the experiment, the density of Scenedesmus obliquus had decreased significantly in the clam-presentmesocosms, and the gut fullness index of bighead carp was significantly higher in the clam-present mesocosms than when clams were absent. Our results show that, under the selected experimental conditions and densities, water clarity improved when bighead carp and Asian clam occurred together, whereas Chl a concentrations and algae biomass increased in the fish-only mesocosms; in the clam-only mesocosms no significant effectswere observed. We suggest that the combination of filter-feeding fish and clams may enhance water clarity and it may therefore potentially be a useful restoration tool.

Subject Keywords

Environmental Engineering, Waste Management and Disposal, Pollution, Environmental Chemistry

URI

https://hdl.handle.net/11511/68257

Collections

Department of Biology, Article