New approaches on the use of tunicates (Ciona robusta) for toxicity assessments

• Published in: Environmental science and pollution research international 2020-09, Vol.27 (25), p.32132-32138
• Main Authors: Eliso, Maria Concetta, Manfra, Loredana, Savorelli, Federica, Tornambè, Andrea, Spagnuolo, Antonietta
• Format: Article
• Language: English
• Subjects: Accidental release; Algae; Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Bioassays; Biodegradation; Biological models (mathematics); Ciona; Ciona robusta; Coastal waters; Coastal zone; Coasts; Crude oil; Crustaceans; Developmental stages; Dicentrarchus labrax; Dispersants; Dispersion; Earth and Environmental Science; Ecotoxicology; Embryogenesis; Environment; Environmental Chemistry; Environmental Health; Environmental science; Ethics; Evaluation; Feeders; Juveniles; Larval development; Marine environment; Mortality; Organs; Pollutants; Pollution control; Shallow water; Shellfish; Short Research and Discussion Article; Surfactants; Toxicity; Vertebrates; Waste Water Technology; Water circulation; Water column; Water Management; Water pollution; Water Pollution Control
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-020-09781-2

After the accidental release of crude oil in marine environment, dispersants are applied on sea surface transferring oil into the water column where it can be broken down by biodegradation, thereby reducing potential pollution to coastal areas. Before they can be used in the wild, the ecotoxicity of such dispersants is usually evaluated with toxicity assays using algae, crustacean and fishes. Nowadays, there is a need to find alternative species to reduce the use of vertebrates both for ethical considerations and for reducing the cost of bioassays. Ciona robusta is a solitary ascidian that inhabits shallow waters and marine coastal areas. This species has been recently adopted as valuable biological model for ecotoxicity studies, thanks to its rapid embryonic and larval development, resemblance to vertebrates, and low risk of ethical issues. On this ground, the lethal and sublethal toxicity of two dispersants has been evaluated on Ciona juveniles. At this stage, the organisms become filter-feeders and the morphological alterations of the organs can be easily observed. The median lethal concentrations at 96 h (96hLC 50 ) for Dispersant 1 (non-ionic surfactant) and for Dispersant 2 (mixture of non-ionic surfactants and anionic surfactants) are 41.6 mg/L (38.6–44.9) and 92.5 mg/L (87.7–97.5), respectively. The Ciona juvenile model was compared to Dicentrarchus labrax fish juveniles test, and it showed increased sensitivity for Ciona to these compounds. These results suggest that 96 h mortality test bioassay could be a good alternative method to 96 h mortality assay with D. labrax , limiting the use of vertebrates for dispersant toxicity.