Influence of 3,4-dichloroaniline (3,4-DCA) on benthic invertebrates in indoor experimental streams

The influence of 3,4-dichloroaniline (3,4-DCA) on benthic invertebrates has been examined. Acute toxicity tests were carried out with the following species: Pristina longiseta, Aelosoma variegatum (Oligochaeta), Hydrozetes lacustris (Acarina), Planorbarius corneus, and Gyraulus albus (Planorbidae). LC50 values (96 hr) were obtained for Pri. longiseta (2.5 mg/liter) and for Hy. lacustris (4.7 mg/liter). For all other species ranges of toxicity (maximal concentration with 0% dead to minimum concentration with 100% dead) were determined. These ranges were 0.8-20 mg/liter 3,4-DCA for Pri. longiseta, 1.6-20 mg/liter, 3,4-DCA for Hy. lacustris, 10-20 mg/liter 3,4-DCA for G. albus, 50-100 mg/liter 3,4-DCA for Pl. corneus, and 10 mg/liter 3,4-DCA (maximal concentration with 0% dead; minimum concentration with 100% dead was not determined) for Ae. variegatum. In two experimental streams, the recolonization of benthic organisms into defined sample areas was studied. Therefore, a phase without chemical treatment was compared with a following exposure phase. Test concentrations were 0.2 and 1.4 mg/liter 3,4-DCA (nominal concentrations). Significant effects were the complete extinction of Pri. longiseta in 0.2 mg/liter 3,4-DCA within the first 3 weeks of exposure, as well as the reduction of immigrating individuals of another species of Pristina in both test concentrations, and of Hy. lacustris and Stentor sp. in 1.4 mg/liter 3,4-DCA.(ABSTRACT TRUNCATED AT 250 WORDS)