Behavioral and Oxidative Stress Responses of Earthworm, Nsukkadrilus mbae (Segun 1976), Exposed to Lead and Cadmium: A Preliminary Investigation

• Published in: Soil & sediment contamination Vol. 30; no. 5; pp. 569 - 589
• Main Authors: Aguzie, Ifeanyi O, Enekwe, Kenechukwu D, Emekekwue, Ijeoma J, Asogwa, Chinweike N, Onyishi, Grace C, Oluah, Ndubuisi S, Ekeh, Felicia N, Nwani, Christopher D
• Format: Journal Article
• Language: English
• Published: Boca Raton Taylor & Francis Ltd 01-07-2021
• Subjects: Bio-assays; Bioassays; Body weight; Burrowing organisms; Cadmium; Contamination; Heavy metals; Lead; Metals; Oxidative stress; Renewal; Soil; Soil contamination; Soil pollution; Soil testing; Soils; Worms
• ISSN: 1532-0383; 1549-7887
• DOI: 10.1080/15320383.2021.1873912

We investigated the behavioural and oxidative stress responses in the earthworm, Nsukkadrilus mbae on exposure to lead (Pb) and cadmium (Cd) contaminated soils. This was because the response of this species to heavy metals ecotoxicity had not been reported. Two concentrations of Pb (20 and 500 µg/g of soil) and Cd (2 and 10 µg/g of soil) and a control (uncontaminated with Pb or Cd) were used in a completely randomized static non-renewal bioassay design. We found that N. mbae more frequently preferred and burrowed into the control soil than the test soils. Avoidance was more at 500 µg/g Pb (ratio: 1:8) and 10 µg/g Cd (ratio: 1:2). The times to start and to complete burrowing, and the interval between both events were significantly extended in test soils, especially at 500 µg/g Pb and 10 µg/g Cd. Heavy metals contamination elicited increased activity of CAT, SOD and GPx, on short-term (day 2, d-2), and increased synthesis of GSH and MDA on short- and long-term (day 30, d-30) in concentration- and duration-dependent manners. The activity of CAT, SOD and GPx declined significantly on d-30. The heavy metals contamination resulted in both a significant loss in body weight, and mortality. Our preliminary results suggest that N. mbae is a suitable model organism for ecotoxicity studies, because it was able to detect and avoid Pb and Cd contaminated soils, delayed burrowing probably in search of suitable soil patches, and even escaped from heavily contaminated soil.