02545nas a2200265   4500008004100000022001400041245013900055210006900194260001300263300001100276490000700287520173200294653001202026653001202038653002102050653001602071653001902087653001502106653001502121653001902136653003102155100001902186700002202205856005202227       2015                        eng d  a1432-070300aAmmonia toxicity to the freshwater planarian <i>Polycelis felina</i>: contrasting effects of continuous versus discontinuous exposures0 aAmmonia toxicity to the freshwater planarian iPolycelis felinai   c2015 May  a689-950 v683 a<p>Aquatic animals can be exposed to fluctuating concentrations of toxicants. In fact, for some toxicants (i.e., pesticides, ammonia), discontinuous exposure is more environmentally relevant than constant exposure. Responses of aquatic animals to each type of exposure may be different. However, despite the high ecological relevance of behaviour, there is still scarce information on the effects of discontinuous exposure on behaviour. Our study focused on the assessment of unionized ammonia toxicity on the behaviour of a freshwater planarian under continuous exposure (3 days of exposure and 18 days of recovery) versus discontinuous exposure (3 pulses of 1 day with 6 days of recovery between pulses = total 3 days of exposure and 18 days of recovery). Behaviour was assessed as locomotion activity. Bioassays with continuous and discontinuous exposure were performed with one control and five unionized ammonia concentrations (0.14-0.35 mg N-NH3/L). Unionized ammonia in continuous exposure caused less impact on behaviour than equivalent concentrations provided in a discontinuous exposure. By contrast, continuous exposures caused more impact on survival. The discontinuous exposure may allow detoxification during recovery periods, thus increasing the probability of survival in the next pulse. Under continuous exposure, the mortality threshold could be exceeded, and animals could die in greater proportion during exposure as well as the recovery period. We conclude that behavioural activity was a sensitive endpoint to assess the contrasting effects of continuous versus discontinuous exposure and that the response of planarians to discontinuous exposure is different to its response to continuous exposure.</p>
10aAmmonia10aAnimals10aBiological Assay10aFresh Water10aLethal Dose 5010aLocomotion10aplanarians10aToxicity Tests10aWater Pollutants, Chemical1 aAlonso, Alvaro1 aCamargo, Julio, A  uhttps://continenticola.myspecies.info/node/1724