Responses in different levels of biological organization in the soil invertebrate Enchytraeus crypticus exposed to field-contaminated soils from a mining area

Abstract

The sub-lethal ecotoxicity of field-contaminated soils toward small soil fauna, such as enchytraeids, remains understudied but holds paramount importance in soil pollution assessment. This study employed Enchytraeus crypticus to evaluate metal-contaminated soils from a mining area across various levels of biological organization, including individual level responses (survival, growth, reproduction, Cd/Pb/Zn accumulation), cellular level effects (peroxidase (POD), superoxide dismutase (SOD), glutathione (GSH), catalase (CAT), acetylcholinesterase (AChE), lipid peroxidation malondialdehyde (MDA)) and genetic alterations (olive tail moment (OTM) and tail DNA%). The study revealed considerable Cd and Pb accumulation, exerting adverse impacts on the reproduction and growth of the enchytraeids after a 21-day exposure. Changes in cellular and genetic parameters occurred with increasing exposure concentration and duration, indicating heightened lipid peroxidation and DNA damage in enchytraeids. A noteworthy metal detoxification process, evident at a physical level, was identified in E. crypticus, characterized by an initial escalation in toxicity followed by a subsequent decline. A distinctive complementary mechanism governing oxidative damage was detected in the enchytraeids, with an initial suppression of CAT activity, followed by inductions in SOD, POD, and GSH activity. Over the exposure duration, MDA content and DNA damage in the enchytraeids exhibited concentration-dependent shifts indicating their potential as efficient early-warning indicators for assessing the impact of Pb-Zn mining soils. This study contributes to a comprehensive understanding of the toxicological implications of metal-contaminated soils within the soil-enchytraeid framework.