The circadian rhythm is a biological rhythm of endogenous origin that repeats with a period of approximately 24 hours. Circadian rhythm in crustaceans is often expressed in locomotor activity. The goal of this study was to analyze the circadian locomotor activity of surface-dwelling water louse (Asellus aquaticus) and establish an experimental system and protocol for the analysis of the evolution of circadian rhythms of this species. We collected animals at Planina Polje and acclimatized them in the laboratory. Then we transferred them individually into Petri dishes and recorded their behavior in 12h:12h LD light regime for seven days, and then in constant darkness, 24h DD, for another seven days. Videos were analyzed using video-tracking techniques. Locomotor activity was shown with a double-plotted actogram and other graphs. Based on the results, we assume that water louse does not have a circadian rhythm of locomotor activity. Their alleged arrhythmicity may be one of the reasons for their multiple successful colonizations of subterranean habitats. Additionally, individuals infected with the parasite Acanthocephalus anguillae had greater locomotor activity than uninfected individuals. We assume this increases the probability of parasite’s transfer from the intermediate (water louse) to the final (fish) host. The conducted study includes potential methodological flaws (e.g., animal starvation, mechanical disturbances), so further research is needed to confirm the above assumptions.
|
