Cadmium pollution alters earthworm activity and thus leaf-litter decomposition and soil properties

• Published in: Environmental pollution (1987) Vol. 267; p. 115410
• Main Authors: Liu, Change, Duan, Changqun, Meng, Xianghuai, Yue, Minhui, Zhang, Hao, Wang, Peng, Xiao, Yanlan, Hou, Zhiyong, Wang, Yuanfeng, Pan, Ying
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.12.2020
• Subjects: Burrowing behavior; Feeding rate; Heavy metal; Physiological adjustment; Soil nutrients; Soil nutrients; Feeding rate; Burrowing behavior; Physiological adjustment; Heavy metal
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2020.115410

It has been reported that heavy metal contamination can affect litter decomposition and soil properties through its impact on microbial communities. However, it is still unclear whether the expected changes in earthworm activities in responses to heavy metal contamination could affect these properties. Therefore, we quantified earthworm (Eisenia fetida) responses in survival rate to lethal cadmium (Cd) concentrations (0, 50, 100, 150, 200, 250, and 300 mg L−1), and in burrowing ability, physiological characteristics, and feeding rate (on poplar leaf litter) to sub-lethal Cd concentrations (0, 15, 30, and 45 mg kg−1). Finally, sub-lethal influences of Cd on the decomposition rate of poplar leaf litter and on soil properties were investigated in the present of E. fetida. The 12-, 24-, 36-, and 48-h LC50 of Cd for E. fetida were 276.0, 208.6, 192.6, 179.8 mg L−1, respectively. With increasing Cd concentration, malondialdehyde was stimulated, superoxide dismutase first increased and then decreased, while feeding rate, total borrowing length, and maximum burrowing depth consistently decreased. Consequently, leaf-litter decomposition rate and soil nutrient concentrations generally decreased with increasing Cd concentration. Our results indicate that, by affecting earthworm activities, Cd inhibited leaf-litter decomposition and led to the degradation of soil fertility. This study highlights the importance of earthworms in mediating soil functions under heavy metal stress. [Display omitted] •Earthworm activities, litter decomposition and soil properties to Cd were analyzed.•Cd caused physiological harm to earthworm cells.•Cd reduced feeding rate, biomass, burrowing ability of earthworms.•Cd reduced litter decomposition rate throughout affected earthworm activities.•Cd led to the degradation of soil fertility by retarding litter decomposition.