engleski

Assessing toxicity to Daphnia magna using movement parameters

Daphnia are among the most common settlers of freshwater habitats. These planktonic invertebrates show high sensitivity to various toxicants, therefore representing a useful model organism in ecotoxicological research – with common endpoints being survival, reproductive success and observable morphological changes. Some of recently conducted scientific investigation involving these organisms focused on examining the effects of various substances on their mobility. The aim of this work was to compare and examine the changes of swimming behaviour of Daphnia over time and under the influence of sub-lethal concentrations of ZnCl , based on 12 chosen movement 2 parameters. Organisms obtained from a natural habitat acclimatized to laboratory conditions were exposed to 5 different sub-lethal concentrations of ZnCl , in 3 replicates. Five organisms were placed in 2 each transparent plastic Petri dish in prepared solutions of the selected toxicant. The recording started instantly upon exposure of the organisms to the toxicant (t ), as well as 1 h, 24 h and 48 h of exposure (dt=1 h, 0 dt=24 h, dt=48 h). The recording and analysis of motion were carried out in Python, implementing OpenCV, TrackPy and NumPy packages. Analysis of the obtained data showed that the duration of exposure affects the movement parameters, regardless of the concentration of the toxicant. Although, some of movement parameters showed significant correlation with concentrations of toxicants and hence can be used as an early biomarker of exposure.

Daphina magna, movement, behavioural toxicology

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