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(19-24) Toxicity of pesticides and PAHs on embryogenesis and early larval growth of the Paracentrotus lividus sea urchin. Fernández, Nuria*,1, Beiras, Ricardo1, 1 Dpto. Ecoloxía e Bioloxía Animal. Facultade de Ciencias. Campus Lagoas-Marcosende, Vigo, Spain ABSTRACT- Polycyclic aromatic hydrocarbons (PAHs) are organic compounds that have been detected in living and nonliving components of ecosystems. They are naturally produced by the incomplete combustion of organic matter. The most important anthropogenic sources of PAHs are petroleum spills and discharges. These compounds are among the most dangerous contaminants in aquatic systems because of their toxic, carcinogenic and mutagenic effects (Kennish, 1992). Also, pesticides are persistent toxicants whose desired activity is the killing of unwanted living organisms and there are a number of possible ways in which humans can be exposed to them. Due to their low solubility, PAHs and pesticides in water column are rapidly sequestered in sediments where they constitute chronic pollution. We have studied the toxic effects of several PAHs (naphthalene, phenanthrene, fluoranthene, pyrene, fluorene and benzo-a-pyrene) and pesticides (lindane, diuron and chlorpyriphos). Bioassays with Paracentrotus lividus sea urchin species have been made. Embryogenesis success and early larval growth have been recorded after incubation of fertilized eggs in seawater and toxicity of singles substances was described by calculating the median effective concentration (EC50) and the lowest observed effect concentration (LOEC). The ranking of toxicity was Naphthalene>Phenentrene>Fluorantrene>Fluorene, Pyrene, Benzo(a)pyrene for PAHs, and Chlorpyriphos> Diuron>Lindane for pesticides, with effective concentration values ranking from 100 to 10000 ppm. Larval growth was a more sensitive response than embryogenesis success in P. lividus. Key words: toxicity test, pesticides, PAHs, Paracentotus lividus |
