The effects of plastics on population structure of microcrustacea

In this study, the effects of PVA (Polyvinyl-Alcohol) and PMA (Polymethacrylic-Acid) which are the raw material for plastics on Daphnia magna was examined. D. magna is a very important species and the first consumer level of the food web. Furthermore, the parameters determining the population structure were investigated and this thesis was aimed to determine how the ecosystem balance changes in relation to the contamination. Different concentration of MP-PVA and MP-PVA solutions were applied on D. magna individuals as acute and chronic exposure. Morphologic characteristics such as length, width and spin were taken from 375 individuals in control and concentration groups and their survivorships, numbers of neonates were recorded. Survivorships, total progeny, net reproductive rate, population size and 𝐿𝐶50values are calculated at the end of the experiment. 𝐿𝐶50 values of MP-PVA in triplicate experiments were recorded as follows: 24.396 mg/L in the chronic assay; 27.773 mg/L in the acute assay. The values of 𝐿𝐶50 for MP-PMA are 14.777 mg/L in the chronic assay, 74.574 mg/L in the acute assay. Morphologic developments have been observed in the chronic and the acute experiments from the first day. Deformation in spin structures has been observed in chronic MP-PVA test. Parthenogenetic females have been seen in chronic MP-PMA assay; on the other hand, the male neonate has been detected in 5 mg/L MP-PVA exposure. Considering acute and chronic experiments individuals that applied MP-PMA had more longevity than other individuals that applied MP-PMA. Besides, there were more neonates in chronic MP-PMA assay compared with other microplastic which was applied. According to the results of these experiments, different results were taken from varying concentrations of microplastic polymers. D. magna has reflected differently in decreasing lifetime, ephippium formation, embryo development, immature eggs and morphologic deformations. It has been found that MP-PMA and MP-PVA have pollutant effects and these microplastic polymers affect population structure of D. magna. KEY WORDS: microplastic, PVA, PMA, lifetable, population structure, Daphnia magna, acute, chronic