RELATIONSHIPS BETWEEN FERTILIZATION OF THE SOUTHEASTERN PACIFIC SEA-URCHIN ARBACIA-SPATULIGERA AND ENVIRONMENTAL VARIABLES IN POLLUTED COASTAL WATERS

Fertilization bioassays with the sea urchin Arbacia spatuligera were u sed to assess the water quality of 9 marine coastal sectors in the Bio bio Region (Southern Chile) and to investigate the relationship betwee n fertilization and environmental variables (in situ pH, turbidity, di ssolved oxygen and salinity), heavy metals (copper, cadmium and mercur y) and organic compounds (oil and grease, lindane, aldrin, dieldrin, D DE, DDT and phenols). The fertilization (mean +/- standard deviation) of A. spatuligera eggs in sectors with high organic discharges from fi shmeal industries such as Rocuant (14.1 +/- 6.0%) and San Vicente (22. 5 +/- 10.0%) was significantly lower (p < 0.05) than in the other sect ors (Chivilingo, Coronel, Lenga, Talcahuano, Pence, Tome, Dichato) (70 .5 +/- 13.0%). Percent saturation of oxygen (r = 0.839), pH (r = 0.830 ), turbidity (r = -0.683) and oil and grease (r = -0.888) showed signi ficant correlations (p < 0.001) with fertilization. Principal Componen t Analysis (PCA) using standardized variables grouped fertilization wi th dissolved oxygen and pH (total variance of 2 first components expla ined 73.0%) and Linear Multiple Regression Analysis produced the follo wing model: Fertilization = 30.001 + 0.785(Percent saturation of oxyge n) - 0.059 (Oil and grease) (r(2) = 0.837; p < 0.001). Rocuant and San Vicente stations were grouped and separated from the rest by inverse PCA and then discriminated by Discriminant Analysis (Hotelling-Lawley Trace, p < 0.001). It was concluded in laboratory bioassays that water s of coastal sectors from Rocuant and San Vicente, with the highest le vels of oil and grease and lowest oxygen concentrations, had a signifi cant effect on the fertilization of A. spatuligera eggs.