Resumen del producto

Raphidophyceans are a group of marine microalgae that have the ability to produce toxic compounds such as brevetoxins (PbTx), reactive oxygen species (ROS) and polyunsaturated fatty acids (PUFAs), which can be harmful to different organisms and can cause mortality mainly in adult fish, although its impact on early life stages of fish is less known. In this study we characterized the toxic effect of Chattonella subsalsa strain of the Gulf of California (Mexico) was evaluated on Paralabrax maculatofasciatus embryos at three development stages: embryo in segmentation (ES), embryo (EM), and eleutheroembryo (EL). For each stage the mortality rate was determined. Embryos (ES) of P. maculatofasciatus were placed (1/well) in microdilution plates. In each well, 1 mL of different cell concentrations (2 to 10 x 103 cell mL-1) of C. subsalsa, the non-toxic dinoflagellate Prorocentrum micans, as well as f/2 medium served as controls. Also, one set of embryos was tested with cell-free media of C. subsalsa cultures with a density between 4 and 8 x 103 cell mL-1. Incubation lasted until embryos reached the apterolarva phase. Embryos were incubated in triplicate at 23° C and 37 ups of salinity. All treatments were repeated five times with different embryo batches. C. subsalsa caused different mortality rates on the early stages of development in P. maculatofasciatus. The ES was the most sensitive embryo stage obtaining 98% mortality, the LC50 of 3.2 x 103 cell mL-1 and the LT50 of 19 h, similar results were observed with cell-free media of C. subsalsa cultures, showing maximum mortalities in ES close to 90 % (LT50 ~40 h), whilst EM and EL phases showed percentages lower than 60 % (LT50 ~70 h). This work confirms that larval stages are highly sensitive to exposure of Chattonella subsalsa strain, which was reflected in a high mortality in a short exposure time; it also showed that direct physical contact with cells is not required to cause mortality.

Palabras clave: Aquatic Toxicology

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