ABSTRACT
Daphnia magna es utilizada como bioindicador ambiental de efluentes dulciacuícolas en ensayos ecotoxicológicos, sin embargo los sistemas de cultivo tradicionales pueden resultar costosos, por lo cual se ha desarrollado un nuevo medio de cultivo. Se aislaron 10 cepas de D. magna, se evaluó el desarrollo de la población (Conteo total de individuos y de hembras grávidas) empleando 3 medios de cultivo, medio A: jugo de alfalfa (0,250 gr/mL), medio B: levadura fresca disuelta y medio C: jugo de alfalfa y levadura disuelta. De las 10 cepas, 4 desarrollaron satisfactoriamente en el medio A, pero no sobrevivieron en los otros medios. En los ensayos ecotoxicológicos agudos frente a dicromato de potasio se encontraron valores promedio de EC50-24h 0,4045 mg/L ± 0,0389 y EC50-48h 0,1857 mg/L ± 0,0072. Con estas 4 cepas se realizaron ensayos ecotoxicológicos agudos para cianuro de potasio, que es un contaminante del sector minero, encontrándose valores de EC50-24h 1,5388 mg/L ± 0,1146 y EC50-48h de 0,6359 mg/L ± 0,0516. Los valores de EC50 a las 48 horas están por debajo del límite permisible para liberación de cianuro en efluentes del sector Energía y Minas.
Daphnia magna is a test organism used in ecotoxicological assays of freshwater; however, traditional culture systems for this organism could result expensive, for that the aim of this research was to developed a new economic culture medium. With this purpose, 10 strains of D. magna were isolated, their population development was evaluated by total count of organisms and pregnant females using 3 different culture media: (A) alfalfa juice, (B) solved yeast and (C) a mixture of alfalfa juice plus solved yeast. Successful development of 4 strains was observed in the A medium, but the same strains failed to survive in the B and the C media. The 24h and 48h EC50 average values in acute ecotoxicological assays with potassium dicromate were 0,4045 mg/L ± 0,0389 and 0,1857 mg/L ± 0,0072 respectively. Also, acute ecotoxicological assays with these 4 strains were performed using potassium cyanide, which is a toxic reactive frequently used in mining operations. In this case 24h EC50 value was 1,5388 mg/L ± 0,1146 and 48h EC50 values were 0,6359 mg/L ± 0,0516. 48h EC50 values were lower than the cyanide permissible effluent values established by the Energy and Mining Authority.