The Effect Of The Herbicide Atrazine Alone And Its Combination With Microcystis On Life History Parameters And Population Dynamics Of Daphnia Magna

One of the most obvious manifestations of eutrophication in water is the outbreak of cyanobacteria blooms,which will release algal toxins and lead to the deterioration of water quality,seriously affecting the safety of water supply,aquaculture water and aquatic products in water supply areas.It is an urgent water environment problem to be solved.With the development of agricultural science and technology in China,herbicides have been widely used in agricultural production.However,herbicides have a significant potential impact on aquaculture: direct harm to fish and indirect harm through the water environment and the food chain.In order to assess the effects of herbicide atrazine and toxic Microcystis on the main zooplankton Cladocerans,we selected ecotoxicology testing mode organism Daphnia magna,which is also a good live food for aquaculture,as experiment material,to study the different concentrations of atrazine on the transgenerational effects of D.magna,and the combined effects of different concentrations of atrazine and toxic Microcystis on the life history parameters of D.magna.This paper draws the following main conclusions:(1)Transgenerational effects of atrazine on D.magnaIn a 14-day life history experiment,on the effects of atrazine at different concentrations on D.magna,the survival,development,and reproduction of the mother and her offspring were observed.It was found that the survival rate and reproduction rate of D.magna exposed significantly.The offspring born from the female D.magna exposed to atrazine cannot fully recover after the pollutants removed.Although no deaths have occurred,their reproduction was still inhibited.These results indicate that atrazine has a transgenerational effect on the D.magna,and even if the atrazine pollution is diminished,it will have a long-term impact on the population of D.magna.(2)Joint effects of atrazine and M.aeruginosa on life history parameters of D.magnaThe present study investigated,in a full-factorial design,the impacts of the selected herbicide atrazine and cyanobacteria Microcystis on key life-history variables in the Daphnia magna.Our results found that atrazine altered the Microcystis-induced life history responses,as a contribution of pronounced mortality and reduced theinhibition on growth and reproduction.Meanwhile,poor-quality food Microcystis increased the atrazine toxicity on life span and reproduction,whereas promoted individual growth to some extent.The present results expanded our knowledge regarding the ecological consequences of harmful algal blooms for freshwater resources located in agricultural areas.In addition,together with previous results in literature,we assumed that interactive effects cannot be generalized for chemical and natural stressors.Therefore,the ubiquity and nature of herbicides toxicity interacting with diet quality are required to be investigated n a greater degree,given that the increasing discharge of herbicides and analogical toxicants in eutrophic waterbody and our demand to control the risk caused by these anthropogenically derived chemicals and natural stressors.The above results showed that atrazine exposure alone interferes with the individual fitness and population abundance of D.magna,and this inhibition has a transgenerational effect;combined with Microcystis,atrazine increases the lifespan of D.magna and toxic effects of reproduction.Due to the long residual period of atrazine in the water environment and the frequent occurrence of toxic Microcystis blooms in the water body,the combined toxicity of atrazine and toxic Microcystis to living food zooplankton should receive long-term attention.