Assessing the toxicity of chemical compounds associated with marine land-based fish farms: The use of mini-scale microalgal toxicity tests

Abstract Many chemicals that are currently used in aquaculture have not been evaluated with regard to their specific effects on the aquatic environment. In the present study, the toxic effects of several chemicals associated with land-based marine fish farming activities were assessed using two species of marine microalgae (Phaeodactylum tricornutum and Isochrysis galbana). Mini-scale toxicity tests were performed with six antibiotics (amoxicillin, ampicillin, flumequine, oxytetracycline, streptomycin and sulfadiazine) and two disinfectants (formaldehyde and hypochlorite). Amoxicillin and streptomycin did not exert toxic effects. Sulfadiazine was the most toxic chemical; the EC50 values were 0.11 mg/L and 1.44 mg/L for P. tricornutum and I. galbana respectively. As expected, the disinfectants displayed high toxicity, and P. tricornutum was particularly sensitive to these compounds. Although the differences in microalgal sensitivity depended on the chemical considered, both species were highly sensitive to most of the compounds tested. We recommend the inclusion of mini-scale microalgal toxicity tests in environmental risk assessment (ERA) and environmental monitoring plans because they are cost-effective and rapid. Keywords: bioassayecotoxicitygrowth testmicroplatephytoplanktonbiomonitoring Acknowledgements This work was funded by the National Plan for Marine Culture (JACUMAR 2008) within a project entitled ‘Selección de indicadores, determinación de valores de referencia, diseño de programas y protocolos y medidas para estudios ambientales en acuicultura marina (INDAQUA).’ M.R. De Orte, is grateful to the European Union for the Erasmus Mundus Scholarship provided. The authors are thankful to Dr. Jaime Fábregas of the Department of Microbiology and Parasitology (University of Santiago de Compostela, Spain) for providing the microalgae and culture medium.