Sea cucumber Holothuria polii (Delle Chiaje, 1823) as new model for embryo bioassays in ecotoxicological studies. (February 2020)

• Record Type: Journal Article
• Authors: Morroni, Lorenzo; Rakaj, Arnold; Grosso, Luca; Fianchini, Alessandra; Pellegrini, David; Regoli, Francesco
• Is Part Of: Chemosphere. Volume 240(2020)
• Publication Date: 2020-02
• Subjects: Embryo bioassay -- Holothuria polii -- Sea cucumber -- Ecotoxicology -- Water quality -- Harbor sediments; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2019.124819
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: The sea cucumbers are common members of marine benthic communities, widespread distributed, easily available and handled. Nevertheless, no data are available on embryo toxicity assays using sea cucumbers, despite some of these species could fully meet the requirements for model test organisms. Holothuria polii is a key species in soft sediments and seagrass meadows; the aim of the present study was the standardization of a new embryo bioassay with this species, as an ecologically relevant test to evaluate the effects of environmental stressors. Sequential experiments were carried out, allowing to define the test acceptability, and a minimum sample size of 240 embryos. Temperature of 26 °C, salinity at 36‰ and a density of 60 eggs/ml were identified as optimum experimental conditions for performing the bioassay. The EC50 calculated for Cd 2+ and Cu 2+ in dose-response experiments indicated a good sensitivity of H. polii, with comparable values with those obtained in embryo toxicity bioassays of other marine invertebrates. An Integrative Toxicity Index (ITI) was calculated by integrating the frequency of abnormal embryos with the severity of observed abnormalities. The index allows to better discriminate different levels of toxicity, appearing particularly relevant for validating the usefulness of H. polii in embryo assays and ecotoxicological studies on environmental quality. Highlights: In this study, a standard methodology of Holothuria polii embryo bioassay was defined. A new integrative toxicity index was developed to refine the sea cucumber bioassay. Good sensitivity of the test to discriminate toxic samples was verified. The bioassay proved a useful tool in future assessment of marine pollution.