Pelagia noctiluca as a new model organism in marine ecotoxicology: effects of common surfactants

: Marine ecotoxicology typically relies on a limited number of invertebrate models used to assess the effects of anthropogenic stressors, including pollutants. Nevertheless, selected model species may not fully represent marine communities and Including sensitive and ecologically relevant organisms is thus crucial. Despite jellyfish are exposed to pollutants via multiple pathways, few species have been investigated for ecotoxicity purposes focusing on the ephyra stage as suitable due to its susceptibility to toxic compounds. Here we explore the use of the mauve stinger P. noctiluca (ephyra stage) as a new model organism in ecotoxicology, by evaluating its responses to two common surfactants. Following optimization of test conditions, P. noctiluca ephyrae were exposed to reference toxicants (SDS and Tween 20). After 24 h and 48 h, both lethal (mortality) and sub-lethal endpoints (behaviour) were evaluated. Both surfactants caused a concentration-dependent increase in mortality, with a milder acute toxicity of Tween 20 (LC50(24 h,48 h) = 0.045 ± 0.00 %) compared to SDS (LC50(24 h) = 7.5 ± 0.6 mg L-1, LC50(48 h) = 6.1 ± 0.8 mg L-1) on P. noctiluca ephyrae. The exposure resulted in evident alterations on ephyrae morphology, with tissue decomposition and lappet damage. The frequency of pulsations was affected at both time-points by surfactants and alterations in the swimming quality were recorded, along with altered lappet contractions or immobility. Our findings show acute toxicity of SDS and Tween 20 to P. noctiluca ephyrae. Their high sensitivity underscores their potential use in ecotoxicological research, improving the impact assessment of pollutants on marine life.