A Preliminary Study About The Effect Of Abnormal Ambient Conditions On Podocyst Reproduction And Life History Stage Transition Of Rhopilema Esculentum

Rhopilema esculentum is a typical representative of cnidaria with a life cycle of generational alternation.The polyps generation of R.esculentum is asexual reproduction with podocyst reproduction and strobilation.The polyps generation is also called asexual generation.The medusa generation of R.esculentum is sexual reproduction and is also called sexual generation.In order to exploit the potential asexual reproduction of R.esculentum,increase the stocks amount of polyps,improve the podocyst reproduction efficiency of R.esculentum and understand the survival strategy and evolutionary selection process of jellyfish,we studied podocyst reproduction of polyps and the selection difference of asexual reproduction and generation transformation during polyps generation of R.esculentum under anormal ambient conditions including high temperature(HT)、temperature decreasing(TD)、temperature increasing(TI)、variable temperature(VT)and so on in depth.We first studied the effect of HT on podocyst reproduction of R.esculentum and found that compared with the 30±0.5℃ high temperature treatment(HT),the ratio of podocyst production(RPP)is 0.2±0.043 ind./d in 26℃ indoor temperature treatment(IT)and0.315±0.049 ind./d in HT group.Polyps tend to choose podocyst reproduction at 30℃ and26℃.The RPP of polyps attached to the base of the floor plates is 0.661±0.031 ind./d and the RPP of polyps attached to the floor plates is 0.433±0.055 ind./d at 30±0.5℃.Then we studied the effect of TD and TI on podocyst reproduction of R.esculentum and found that compared with the 30.3±0.5℃ HT,the RPP is 0.048±0.015 ind./d in 20-14℃temperature decreasing treatment(TD)and 0.339±0.047 ind./d in HT group.The RPP is0.075±0.029 ind./d in 14-22℃ temperature increasing treatment(TI)and 0.475±0.059 ind./d in HT group.Polyps tend to choose podocyst reproduction at 30℃ HT、TD and TI.We studied the effect of VT on podocyst reproduction of R.esculentum at last and found that compared with the 30±0.5℃ HT,the RPP is 0.183±0.027 ind./d in 28-33℃ temperature loop variation treatment(LVT)and 0.204±0.027 ind./d in HT group.Compared with the30.4±1.2℃ HT,the RPP is 0.250±0.047 ind./d in the huge variable temperature treatment(HVT)and 0.370±0.059 ind./d in HT group.Polyps tend to choose podocyst reproduction at30℃ HT、LVT and HVT.The results show that polyps tend to produce more podocyst and the podocyst reproduction efficiency is higher when polyps attached to the base of the floor plates at 30℃.Compared with the TD and TI below 30℃,the HT about 30℃ could increase the RPP of R.esculentum by 5～6 times.We directly prove that 30℃ or so high temperature can significantly improve the podocyst reproduction efficiency of R.esculentum’s polyps.Polyps tend to maintain asexual generation to survive adverse ambient conditions in a more economical way.It also suggests that the pressure of global warming,which has become increasingly serious in recent years,may be an important factor in jellyfish bloom.