Phototactic behavior of Daphnia and the continuous monitoring of water quality: Interference of fish kairomones and food quality

Abstract

We carried out a laboratory study to evaluate the sensitivity of phototactic behavior of Daphnia magna to sublethal concentrations of pentachlorophenol (PCP) and copper. More specifically, we determined whether the sensitivity of a D. magna clone to those pollutants is influenced by food quality and the presence of fish kairomones. Test animals were fed either unicellular green algae (Scenedesmus acutus) or fresh baker's yeast (Saccharomyces cerevisiae) and were cultured in the presence or absence of fish kairomones. Four concentrations of PCP (0.4, 0.8, 1.2, and 1.6 mg/L PCP) and one concentration of copper (0.02 mg/L Cu2+) in International Standards Organisation (ISO, Geneva, Switzerland) standard medium were applied in the experiments. Animals were exposed for 3 h to the pollutants prior to the experiments. In the absence of fish kairomones, a strong negative relationship between the phototactic index and nominal sublethal concentrations of PCP was found in animals fed either algae or yeast. The sensitivity of the Daphnia clone to sublethal concentrations of PCP was, however, less clear cut in animals fed yeast than in animals fed algae. The detection limit was 0.4 mg/L PCP with algae as food but was as high as 1.2 mg/L PCP when yeast was used as food. The ability to detect sublethal concentrations of copper and PCP using phototactic behavior was lost when the clones were cultured in the presence of fish kairomones. At a concentration of 0.02 mg/L Cu2+ and in the absence of fish kairomones, the D. magna clone tested became significantly less positively phototactic than in the control treatment regardless of the quality of the food used to culture the test animals. These results suggest that assays using the phototactic behavior of Daphnia to monitor water quality should use genetically stable (clonal) material, positively phototactic, and insensitive to the presence of fish kairomones.

Thermal variation and factors influencing vertical migration behavior in Daphnia populations

“…The lack of vertical migration by all isolates suggests that even at low levels metals are interfering with Daphnia’s response to fish kairomone cues. Similar findings have been shown in other studies examining invertebrate predator kairomone and their influence on Daphnia neonate neckteeth development in the presents of these same metals (Hunter and Pyle, 2004; Mirza and Pyle, 2009), and fish kairomone influence on photo-tactic behavior of Daphnia in the present of Cu (Dang Kieu et al, 2001; Yuan et al, 2003). While our study confirms earlier findings about copper it adds nickel to the list of metals that at low concentrations inhibits Daphnia’s responds to predatory fish cues.…”

Influence of a Xenobiotic Mixture (PCB and TBT) Compared to Single Substances on Swimming Behavior or Reproduction ofDaphnia magna

“…Other results showed that cadmium decreased the velocity of Daphnia magna [24]. In the absence of pollutants, a clone (Daphnia magna) showed positively phototactic behavior, and the behavior became significantly less positive with increasing concentrations of a chemical substance [25]. In our opinion, the behavior of animals ensures ecological reactivity and adaptation to their (e.g.…”

Histaminergic signaling in the central nervous system of Daphnia and a role for it in the control of phototactic behavior

“…food abundance and quality, and the presence/absence of fish kairomones (e.g. Michels and De Meester, 1998;Cousyn et al, 2001;Kieu et al, 2001). Phototactic behavior in daphnids is also influenced by a variety of environmental pollutants (Michels et al, 2000;Semsari and Megateli, 2007;Brausch et al, 2011) and, given its relative ease to observe and quantify (Dojmi and Rotondo, 1988), has been used to monitor for these chemicals (e.g.…”