Combining bivalve (Corbicula fluminea) and filter-feeding fish (Aristichthys nobilis) enhances the bioremediation effect of algae: An outdoor mesocosm study

The research article “Combining bivalve (Corbicula fluminea) and filter-feeding fish (Aristichthys nobilis) enhances the bioremediation effect of algae: An outdoor mesocosm study”, co-authored by METU visiting researcher Prof. Erik Jeppesen, has been published in Science of the Total Environment.

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 μg L−1 compared with 36 μg L−1 in the clam-only treatments and 31 μg L−1 in the controls, whereas Chl a in the fish-only group had increased to 211 μg 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-present mesocosms, 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 effects were 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.

Shen, R., Gu, X., Chen, H., Mao, Z., Zeng, Q., & Jeppesen, E. (2020). Combining bivalve (corbicula fluminea) and filter-feeding fish (aristichthys nobilis) enhances the bioremediation effect of algae: An outdoor mesocosm study. Science of the Total Environment, 727 doi:10.1016/j.scitotenv.2020.138692

Article access: https://www.sciencedirect.com/science/article/pii/S0048969720322099

Keywords:

Asian clam; Bighead carp; Biomanipulation; Cyanobacteria; Filter-feeding

Other authors:
Shen R., Gu X., Chen H., Mao Z. & Zeng Q.

Acknowledgments:
We would like to express our deep gratitude to Jinquan Wei, Wei Li, Tianheng Tong, and Jingchen Xue for their help with sampling and nutrient analysis and to Anne Mette for English improvement of our manuscript. We would also like to thank the Taihu Laboratory for Lake Ecosystem Research for providing us with the experimental facility for this study. This study was financially supported by the National Natural Science Foundation of China (No. 31930074 , 31870449 ), Lake Taihu Management Project of Jiangsu Province ( TH2019303 ), Jiangsu Provincial Aquaculture Foundation of China (No. Y2017-26 ), and Water Conservancy Science and Technology Project of Jiangsu Province (No. 2017013 ). EJ was supported by the TÜBITAK BIDEB 2232 outstanding researcher program.