Effects Of Glyphosate On Growth,Reproduction And Antioxidant System Of Daphnia Magna

Glyphosate?GLY?is a non-selective herbicide,also known as Zhen Cao Ning,Nong Da.Glyphosate is widely used in agricultural weeding and other environments.The agricultural use of glyphosate can cause it to rherbicides may reach aquatic systems by leaching,run-off or by adsorption to particulate matterr,affecting the morphology,behavior and physiology of aquatic organisms,potentially threatening human health.There have been many reports on the toxicity of glyphosate,and the toxicity studies on aquatic organisms have focused on fish and algae.As an important member of the aquatic ecosystem,zooplankton affects the aquatic ecological food chain.In the study of glyphosate on Daphnia magna of the horns,they are only limited to studies on the apparent effects of Daphnia magna.There are few reports on the Daphnia magna antioxidant system and toxicity mechanisms.In this study,Daphnia magna were used as experimental subjects to investigate the toxicproperties of glyphosate on Daphnia magna and the effects on the feeding and reproduction of Daphnia magna through acute toxicity experiments.To explore the effects of chronic exposure of glyphosate on the growth and reproduction of Daphnia magna,through the 21st chronic exposure experiment of the mother and its different offspring.To explore the effects of acute and chronic exposure of glyphosate on Daphnia magna antioxidant systems,through the detection of antioxidant-related system enzymes.Through ROS detection,we can understand the toxicity of glyphosate in Daphnia magna to explain the basic mechanism of glyphosate toxicity to Daphnia magna cells.The main results obtained from the above studies are as follows:1.The results of acute toxicity test showed that glyphosate was 228.401 mg/L and 216.113 mg/L for 24 h and 48 h-LC₅₀,respectively,indicating that glyphosate was a low-toxic substance for Daphnia magna.2.The results of acute toxicity tests at different ages showed that the sensitivity of Daphnia magna to glyphosate gradually decreased with the increase of age,but the sensitivity to glyphosate was enhanced when it was pregnant.3.The results of the feeding inhibition experiment showed that the acute exposure of glyphosate caused a decrease in the feeding behavior of Daphnia magna,which led to a significant decrease in the filtration rate and ingestion rate of Daphnia magna.4.The results of 21-day chronic exposure to Daphnia magna growth and reproduction showed that the glyphosate exposure for 21 days made the first birth time relatively advanced,increased the number of first offspring and the total number of offspring in 21 d,but there was no significant effect on the number of molting on 21 d,and the degree of influence increased with the increase of glyphosate concentration.Comparing the data of mother and offspring,the effect of 21 d exposure on offspring is greater than that of mother.The toxicity of glyphosate can be accumulated along the progeny.5.The results of 21-day chronic exposure and acute exposure to antioxidant enzymes showed that the chronic exposure caused SOD activity and T-AOC content in Daphnia magna to increase first and then decrease with the increase of glyphosate concentration,and the activity of CAT decreased significantly,indicating that chronic exposure caused Daphnia magna oxidative damage,and the offspring are more damaged than the mother.6.The results of ROS fluorescence detection showed that the toxicity of glyphosate in Daphnia magna was mainly concentrated gill.The results of fluorescence comparison between the offspring and the mother show that the offspring are highly toxic.The results of this study indicate that glyphosate exposure has an effect on the growth and reproduction of Daphnia magna and feeding behavior,resulting in the blockage of normal growth and development of Daphnia magna,causing oxidative damage of Daphnia magna cells.This study preliminarily explored the mechanism of oxidative damage of glyphosate on Daphnia magna and the effect on growth and reproduction.It enriches the toxicity mechanism of glyphosate to Daphnia magna,and provides a scientific basis for the safe use of glyphosate and the protection of aquatic ecosystems.