Effects Of Temperature And Food On Asexual Reproduction Of Aurelia Sp. Polyps From Different Geographic Population

Aurelia sp.is one of the dominant species of common large jellyfish in global coastal waters,and it is widely distributed in subtropics and temperature zones.In recent years,jellyfish blooming has been an ecological disasters,which causes much negative effects on coastal economic activities.Therefore,the jellyfish blooming mechanism is a hot scientific issue at home and abroad.Aurelia sp.has a complex life history,which is divided into two stages:non-motile polyps,motile ephyrae and adult jellyfish.The first stage is considered to be a key period for population expanding,because in this stage,polyps will adopt flexible reproductive strategies and methods to amplify populations under different surroundings.In order to understand jellyfish blooming mechanism better,it is necessary to conduct an in-depth study about the impact of environmental factors on various stages of the Aurelia sp.Along with global warming and eutrophication intensifing,a potential favorable condition is provided for jellyfish blooming with more suitable temperature and food level.Domestic and foreign scholars have carried out much researches on environmental regulation mechanisms of Aurelia sp.polyps,but most are mainly focus on Aurelia sp.polyps in separate sea area,which has limitations to some extent.This paper select five Aurelia sp.polyps from different geographic populations as research objects based on the existing experiments.Three temperature?10?,15?,20??and two food conditions?starvation and overfeeding?,a total of six combinations were setted to study the effects on asexual reproduction ability and reproduction mode of Aurelia sp.polyps.The results are as follows:The asexual reproduction ability of Aurelia sp.polyps was significantly affected by temperature,food and different populations?P<0.01?.The number of newly produced Aurelia sp.polyps under high temperature and sufficient food conditions was higher.When the temperature is 20?and the food was sufficient,the polyps of Aurelia sp._USA produced more newly polyps than polyps of Aurelia sp._Slovenia,Aurelia sp._China,Aurelia sp._Spain and Aurelia sp._Israel.2.A total of 7 different asexual reproduction methods were observed in this study:lateral budding,lateral budding by means of stolons,reproduction from parts of stolons,motile bud-like tissue particles,podocysts,strobilization and longitudinal fission.Among them,lateral budding,lateral budding by means of stolons and reproduction from parts of stolons are common asexual reproduction mode of five Aurelia sp.polyps.And the polyps of Aurelia sp._USA had all seven asexual reproduction modes,moreover,the strobilization reproduction mode was only observed in polyps of Aurelia sp._USA.3.The asexual reproduction modes of Aurelia sp.polyps from different geographic populations are different with the influences of food and temperature,they had specific dominant asexual reproduction modes.As one of the multi-mode species,Aurelia sp.had the ability to alter their asexual reproduction modes to adapt to environmental conditions.Only in this way,can they improve the adaptability of different conditions and enhance the potential for blooming.In general,under the conditions of suitable temperature and sufficient food,the Aurelia sp.usually choose the asexual reproduction mode of budding,including lateral budding and lateral budding by means of stolons.In this study,we investigated the asexual reproduction rate and population density of five different Aurelia sp.populations under six combinations of temperature and food conditions,and explained the effects of temperature and food on asexual reproduction ability and modes of polyps,aiming to provide basic data supports for revealing the key driving factors of jellyfish blooming and improve warning ability of jellyfish disasters.In addition,our research made a data supplement for environmental regulation mechanisms of Aurelia sp.polyps.