108 | Emerging models for emerging contaminants

Camilla Mossotto^1|2, Alice Gabetti¹, Alessandra Maganza^1|2, Alessia Merialdi¹, Antonia Concetta Elia², Monia Renzi³, Giuseppe Esposito¹, Marino Prearo¹, Caterina Faggio⁴, Paolo Pastorino¹ | ¹Istituto Zooprofilattico del Piemonte, Liguria e Valle d’Aosta, Torino, Italy; ²Università di Perugia, Italy; ³Università degli Studi di Trieste, Italy; ⁴Università degli Studi di Messina, Italy.

Marine ecotoxicological risk assessment relies on a limited range of biological models, particularly in the case of benthic environments, thereby limiting the ecological realism of toxicity evaluations. Although echinoderms are widely recognised as sensitive and ecologically relevant organisms, experimental research has predominantly focused on sea urchins, leaving other echinoderm classes insufficiently explored. This study combines a critical literature review on sea stars (class Asteroidea) and brittle stars (class Ophiuroidea) with targeted experimental evidence to evaluate their potential as models for assessing emerging contaminants in marine ecosystems. A systematic evaluation of ecotoxicological studies published over the past two decades was conducted to assess the use of sea stars and brittle stars in toxicity testing, with particular attention to experimental design, biological endpoints, and ethical considerations. The analysis reveals that research on these classes is sporadic and unevenly distributed, with a strong emphasis on bioaccumulation endpoints and a focus primarily on metal exposure, while only a limited number of studies have addressed emerging contaminants. In contrast, fewer studies have investigated functional or physiological endpoints. Moreover, the literature suggests that both sea stars and brittle stars exhibit a range of sensitive, non-lethal endpoints suitable for repeated measures testing and long-term exposure scenarios. Based on the identified knowledge gaps, targeted experimental assays were designed to explore the applicability of brittle stars as models for emerging contaminants. Two brittle star species collected from the gulf of La Spezia (Ligurian Sea, Italy) were exposed for seven days to gadolinium, a rare earth element increasingly detected in aquatic environments due to its widespread use in medical imaging and green technologies, across a concentration range of 0 to 1000 µg/L. This short-term exposure was used to establish baseline tolerance and assess sublethal physiological responsiveness. The absence of acute mortality, together with the detection of measurable oxidative stress responses, supports the suitability of brittle stars for controlled laboratory testing and potential chronic exposure studies. Overall, this work highlights the potential of sea stars and brittle stars as emerging ecotoxicological models for investigating poorly studied contaminants within echinoderm research. Incorporating these taxa more systematically into ecotoxicological bioassay frameworks could broaden taxonomic coverage and enhance the ecological relevance of marine pollution assessments.