Interfering Effects Of Sertraline On Cladoceran-induced Antipredation Defense

Cladoceran is an important part of the aquatic ecosystem.When facing predators,it can produce diverse inducible defense characteristics.The inducible defense of cladocerans plays an important role in maintaining the balance of the interspecific relationship between cladocerans and predators.Therefore,"predator-cladocerans"is a model for studying the relationship between species in aquatic ecosystems.Due to human behavior and sewage treatment technology,the discharge of antidepressants in natural water has gradually increased,which is becoming a new type of endocrine pollutant.The current researches on the effects of antidepressant pollution are mainly focused on the toxicity to aquatic organisms,but there is still a lack of knowledge of its impact on the interspecies relationship of aquatic ecosystems.Combining the mechanism of action of antidepressants and the formation mechanism of inducible defense of cladocerans,we speculated that antidepressants may affect the nerve signal transduction of cladocerans,thereby affecting the transmission of kairomone and leading to changes in inducible anti-predation defense.However,how does antidepressant pollution affect the inducible defense of cladocerans?Will this effect change the inducible defenses of cladocerans?In order to answer the above scientific questions,this study evaluated the effect of the antidepressant sertraline on the inducible anti-predator defenses of cladocerans from the perspective of multiple species,multiple predators and multiple generations.1.The effects of sertraline on the response of Ceriodaphnia cornuta to Chaoborus larvae kairomoneTo clarify the effect of antidepressant pollution on the response of cladocerans to invertebrate predator kairomone,we studied the effects of different antidepressant sertraline concentrations(0,0.2,2,20 and 100?g L^-1),a selective serotonin reuptake inhibitor,on the induced defensive traits of Ceriodaphnia cornuta in response to invertebrate predator Chaoborus larvae kairomone,including morphological defense and life history traits.We also conducted the predation experiments to check the selection rate of Chaoborus larvae during directly ingesting C.cornuta that were exposed to Chaoborus larvae kairomone at high concentration of sertraline.Results showed sertraline had an interference effect on the induced morphological defense of C.cornuta in response to Chaoborus larvae kairomone,i.e.the high concentration of sertraline(20 and 100?g L^-1)significantly reduced the horn induction.However,regardless of presence or absence of Chaoborus larvae kairomone,different concentrations of sertraline generally did not affect the life history traits of C.cornuta.The predation experiment demonstrated that the inhibition of sertraline on the induced morphological defense of C.cornuta can promote the feeding selective efficiency of Chaoborus larvae,and thus caused C.cornuta easily to be ingested by Chaoborus larvae.Our results suggested that sertraline at the concentrations that are not direct harmful to life history traits of C.cornuta can seriously affect the relationship between Chaoborus larvae and C.cornuta.2.The effects of sertraline on the response of Daphnia magna to fish kairomone and its related gene expressionIn order to reveal the effect of antidepressant pollution on the response of cladocerans to vertebrate predator kairomone,we studied the effects of different sertraline concentrations(0,0.2,2,20 and 100?g L^-1)on the induced defensive traits of Daphnia magna in response to fish(Rhodeus ocellatus)kairomone.We also tested the related gene expression of inducible defenses.Results showed that sertraline can significantly reduce the changes of relative expression in Acetyl cholinesterase(AchE),DOPA decarboxylase 1(Ddc1)and Vitellogenin 2(Vtg2)of D.magna and inhibit the life history defense of D.magna,including the defense response of the body length at sexual maturation and the body length of neonate.With the increasing of sertraline concentrations,these inhibitory effects became more obvious.Sertraline also significantly increased the relative expression and change of Superoxide Dismutase-Cu/Zn(SOD-Cu/Zn),and enhanced the oxidative stress of D.magna.Therefore,sertraline inhibited the inducible defenses of D.magna and affected the predation relationship between fish and D.magna.3.The effects of environmental concentration of sertraline on the response of Daphnia pulex to fish kairomone and its transgenerational effectsBased on the first two chapter,this experiment focused environmental concentration of sertraline(0,0.2 and 20?g L^-1)on the inducible defense of Daphnia pulex in response to fish(Rhodeus ocellatus)kairomone.We also evaluated the effect of the inducible defense of the offspring which mother had undergone different sertraline treatments and the mother had undergone different fish kairomone treatments in response to fish kairomone.Experimental results showed that sertraline(0.2?g L^-1)not affected the life history defense and morphological defense of D.pulex in F1 generation,but it enhanced the life history defense and morphological defense in F2 generation;Sertraline(20?g L^-1)promoted the life history defense and morphological defense of D.pulex in the F1 and F2 generations.In general,sertraline promoted D.pulex life history defense and morphological defense.In addition,we also found that the maternal experience of fish kairomone inhibits the promoting effect of sertraline on the defense induction of offspring D.pulex.In summary,sertraline had diverse interference effects on the inducible anti-predation defense of cladocerans:high concentration of sertraline inhibited the morphological defense of C.cornuta and the life history defense of D.magna,but it promoted life history and morphological defense of D.pulex and had a transgenerational effect.These results indicated that sertraline pollution may interfere with the dynamic balance between cladocerans and predators,and also have a great significance for evaluating the impact of the antidepressant sertraline on the interspecies relationship of aquatic ecosystems.