Robert E. Reinert 1972 <i>Scenedesmus obliquus</i>, <i>Daphnia magna</i>, and <i>Poecilia reticulata</i> accumulated dieldrin directly from water; average concentration factors (concentration in organism, dry weight, divided by concentration in water) were 1282 for the alga, 13,954 for<i> D. magna</i>, and 49,307 (estimated) for the guppy. The amount accumulated by each species at equilibrium (after about 1.5, 3-4, and 18 days, respectively) was directly proportional to the concentration of dieldrin in the water. <i>Daphnia magna</i> and guppies accumulated more dieldrin from water than from food that had been exposed to similar concentrations in water. When guppies were fed equal daily rations of <i>D. magna</i> containing different concentrations of insecticide, the amounts of dieldrin accumulated by the fish were directly proportional to the concentration in <i>D. magna</i>; when two lots of guppies were fed different quantities of <i>D. magna</i> (10 and 20 organisms per day) containing identical concentrations of dieldrin, however, the amounts accumulated did not differ substantially. application/pdf 10.1139/f72-219 en Accumulation of dieldrin in an alga (<i>Scenedesmus obliquus</i>), <i>Daphnia magna</i>, and the guppy (<i>Poecilia reticulata</i>) article