Evaluation of mysids and sea urchins exposed to saxitoxins

•A specie of mysid and two of sea urchins were exposed to saxitoxins in different toxicological tests.•The acute test with Mysidopsis juniae showed mortality at a LC50 = 2.34 μg/L STX eq.•The values of EC50 found to sea urchins showed effects of abnormality to both larvae.•Different sensibilities could be compared (EC50 = 2.96 μg/L for L. variegatus and 2.06 μg/L for A. lixula).•A. lixula is another option available to ecotoxicological biomonitoration.

Saxitoxins are neurotoxins produced by dinoflagellates and cyanobacteria that form toxic blooms in waters. The impact of saxitoxins to the most vulnerable taxa and environment are not well understood. The experimental model was based on the use of toxic cell extracts containing saxitoxins. This extract was utilized for acute and chronic tests with Mysidopsis juniae. Chronic tests were also done with Lytechinus variegatus and Arbacia lixula larvae. Acute test with mysids had a LC50 = 2.34 μg/L. The chronic test with sea urchins showed morphological abnormalities resulting in malformation of larval appendices at low concentrations of the toxin (EC50 = 2.96 μg/L for L. variegatus and 2.06 μg/L for A. lixula). Although saxitoxins are considered neurotoxins, both species of sea urchins showed symptoms not related to nerve cells. A. lixula was more sensitive than L. variegatus, proving that its sensitivity should be taken in consideration to be another option to toxicological tests.