The early warning of aquatic organophosphorus pesticide contamination by on-line monitoring behavioral changes of Daphnia magna

In this paper, the movement behavior of Daphnia magna was studied as a bio-indicator of organophosphorous pesticide (OP) contamination, using an on-line bio-monitoring method, the Multispecies Freshwater Biomonitor. A static test of acute toxicity test revealed the 24-h and 48-h LC(50) values (95% confidence limit) for Daphnia magna to be respectively 0.45 microg/l and 0.21 microg/l for dipterex 3.80 microg/l and 0.90 microg/l for malathion, and 1.25 microg/l and 0.38 microg/l for parathion. The behavior strength of Daphnia magna was a sensitive indicator of sublethal OP stress and resulted in significant concentration-response relationships for the three OPs. Increasing OP concentration will result in more intensive behavioral responses of Daphnia magna and shorter response time, which could be described by the Stepwise Stress Model (SSM). Therefore movement behavior can be effectively applied in early warning of environment quality by on-line bio-monitoring. The intensive changes in behavior strength of Daphnia magna over a short time follow the SSM concept and can be used as an indicator of early stress response to OP accidental contamination.     

Effects of nickel chloride and oxygen depletion on behaviour and vitality of zebrafish (Danio rerio, Hamilton, 1822) (Pisces, Cypriniformes) embryos and larvae

We examined acute (2 h exposure of 5-day-old larvae) and subchronic (exposure from fertilization up to an age of 11 days) effects of NiCl(2).6H2O on embryos and larvae of zebrafish (Danio rerio), both alone and in combination with oxygen depletion. The following endpoints were recorded: acute exposure: locomotory activity and survival; subchronic exposure: hatching rate, deformations, locomotory activity (at 5, 8 and 11 days) and mortality. In acute exposures nickel chloride (7.5-15 mg Ni/L) caused decreasing locomotory activity. Oxygen depletion (or=10 mg Ni/L resulted in delayed hatching at an age of 96 h, in decreased locomotory activity at an age of 5 days, and increased mortality at an age of 11 days (LC20=9.5 mg Ni/L). The observed LOEC for locomotory activity (7.5 mg Ni/L) is in the range of environmentally relevant concentrations. Since locomotory activity was already affected by acute exposure, this parameter is recommended to supplement commonly recorded endpoints of toxicity.     

Measurement of movement patterns of Caenorhabditis elegans (Nematoda) with the Multispecies Freshwater Biomonitor® (MFB)—a potential new method to study a behavioral toxicity parameter of nematodes in sediments

The nematode Caenorhabditis elegans receives increasing attention in sediment ecotoxicology and new toxicity tests with sensitive test parameters are under development. In this study, the motility of C. elegans could be measured for the first time online in sediment, using the Multispecies Freshwater Biomonitor. Whereas single nematodes could not be recorded, groups of 10 nematodes gave typical locomotive signals in different media (water, agar, sediment) with comparable precision and accuracy. The results of this study encourage to develop a new rapid online whole-sediment toxicity test with behaviour as sensitive test parameter.