Generational Toxicity and Incomplete Recovery from Spent Lithium-Ion Battery Leachate in an Aquatic Microinvertebrate <i>Brachionus asplanchnoidis</i>

Spent lithium-ion batteries (LIBs) are a rapidly growing solid waste; mismanagement generates metal-rich leachate that threatens aquatic environments. We evaluated the molecule-to-population responses of the zooplankton <i>Brachionus asplanchnoidis</i> to leachate from retired 18650 cells across single-generation exposure, postexposure recovery, and multigenerational propagation and tested whether monosodium glutamate (MSG) accelerates recovery. Rotifers were exposed to 5% (volume/volume, v/v) leachate and assessed for morphological, feeding, life-history, population, metabolomic, biochemical, and gene-expression end points. Chemical profiling confirmed elevated Li, Fe, Al, Co, Ni, and Mn above seawater background. Leachate suppressed growth and feeding within and across generations, and poststress recovery was asynchronous, with feeding rebounding faster than body size and life-history traits. In multigenerational assays, the exposure lineage collapsed by F₄, whereas recovery lineages showed progressive improvement, approaching control levels by ∼F₆ in the transgenerational lineage and by ∼F₄ with MSG supplementation. Metabolomics revealed 189 differential metabolites and distinct exposure-recovery signatures centered on amino acid and energy metabolism. Gene expression supported metallothionein-mediated detoxification under the measured metal burden. By integrating short- and long-term perspectives, this study demonstrates multilevel toxicity, incomplete and phased recovery, and the potential of targeted nutritional support to enhance resilience and poststress performance, informing mixture-aware environmental risk assessment of LIB leachate.