Enhanced Toxicity of Diol-Estered Diarrhetic Shellfish Toxins Across Trophic Levels: Evidence from Caenorhabditis elegans and Mytilus galloprovincialis

<i>Prorocentrum lima</i> is a widely distributed and major source of diarrhetic shellfish toxins (DSTs); the ecological impact of diol-estered DSTs (eDSTs) compounds on benthic systems is still inadequate. In this study, the acute toxicity of eDSTs was evaluated in <i>Caenorhabditis elegans</i>, and their accumulation capacity and toxic effects were examined in <i>Mytilus galloprovincialis</i> for an ecological risk assessment. The results indicated that larvae 1 (L1) was more sensitive than larvae 4 (L4) of <i>C. elegans</i>, and the eDSTs in <i>P. lima</i> extract lysate were more toxic than the okadaic acid (OA) standard solution. The lowest LC₅₀ values were 0.293 and 0.469 μg/mL for L1 and L4, respectively. The growth, productivity, and intestinal permeability of <i>C. elegans</i> were impaired, and the effect of <i>P. lima</i> extract lysate on <i>C. elegans</i> was greater than that of the OA standard solution. The total toxin concentration in the digestive gland of mussels reached 3230 μg/kg, with esterified DSTs accounting for 76.7-97.1% of total toxins and inducing marked oxidative stress. Diol-estered DSTs exert direct toxic effects, including oxidative damage and growth inhibition, while exhibiting a high accumulation potential. This study revealed the toxicity of eDSTs, necessitating a focused investigation to comprehensively assess their toxicological impact and ecological risks.