Effects of PAH-spiked microplastics on macroalgae and microalgae growth

Abstract

Effects of PAH-spiked Microplastics on Macro and Microalgae growth Tan Hui Ying Renee Ongoing discourse on microplastics and its adsorbable pollutants’ effects on marine life has highlighted the need for more relevant research. Aligned to this, this study aimed to research the impact of microplastics spiked with PAHs on macroalgae and microalgae growth using novel small-scale laboratory assays. The assays were conducted on the macroalgae Caulerpa lentillifera (7-day duration) and the microalgae Tetraselmis suecica (72-hour duration) with spiked and unspiked microplastic treatment types. A 144-hour continuous absorbance plate-reader assay was also conducted on microalgae. The 7-day macroalgae assay was hindered by external factors which resulted in a lower number of replicates than originally designed. The low statistical power of these results meant that a relationship between PAHs and macroalgae could not be drawn. The 72-hour microalgae experiment produced results that supported the hypothesis that spiked microplastics and microplastics by itself do not have an effect on microalgae growth. Conversely, the 144-hour growth curves did have observable differences where 0.1mg/ml concentration of spiked microplastics resulted in faster decline in growth after the 11th hour than lower concentrations. This suggests a relationship where higher concentrations of spiked microplastics cause lower microalgae growth over a longer duration, but the methodology requires further optimization.