title: Daphnia response to biotic stress is modified by PCBs.
abstract: The aim of this study was to examine the influence of xenobiotics (PCBs) on the responses of Daphnia to biotic factors such as the presence of a predator (fish kairomone) or filamentous cyanobacteria. Both behaviour (depth selection) and life history (body size at first reproduction and fecundity) were affected by these stressors. Though there was no direct effect of PCBs, their influence resulted in disruption of the "natural" reaction to the presence of fish or cyanobacteria, leading to inadequate responses of Daphnia to these biotic threats. Examined clones of Daphnia showed significant diversity in their reaction to these stress factors, which was greater than that between Daphnia clones exposed to different environmental conditions. PCB pollution may change the frequency of Daphnia clones in favour of those whose responses to biotic stress are similar in both the absence and presence of these toxic chemicals.
authors.affiliation: Department of Hydrobiology, Faculty of Biology, University of Warsaw, Banacha 2, 02-097 Warsaw, Poland. p.p.bernatowicz@uw.edu.pl
authors.forename: Piotr
authors.initials: P
authors.lastname: Bernatowicz
authors.forename: Joanna
authors.initials: J
authors.lastname: Pijanowska
mesh_terms: D000818:Animals; D000458:Cyanobacteria / Q000472:pathogenicity; D003621:Daphnia / Q000187:drug effects* / Q000382:microbiology / Q000502:physiology; D004777:Environment; D005298:Fertility / Q000187:drug effects; D005399:Fishes / Q000378:metabolism; D005618:Fresh Water / Q000737:chemistry / Q000382:microbiology; D010675:Pheromones / Q000633:toxicity; D011078:Polychlorinated Biphenyls / Q000633:toxicity*; D013312:Stress, Physiological; D014871:Water Microbiology; D014874:Water Pollutants, Chemical / Q000633:toxicity*; D015262:Xenobiotics / Q000633:toxicity*
chemical_list: D010675:Pheromones; D014874:Water Pollutants, Chemical; D015262:Xenobiotics; D011078:Polychlorinated Biphenyls