Glitter Interference On Photosynthetic Rates of A Submerged Macrophyte (Egeria Densa)

Abstract

This study analyzed the photosynthetic rates (by the light and dark bottle method) of the submerged macrophyte Egeria densa in the presence of three concentrations of glitter: 0.0235 g (T1/T4), 0.0117 g (T2/T5) and 0.0058 g (T3/T6), as well in its absence (control treatment, CT1 and CT2). About 800 apical fragments of E. densa were distributed in 8 subtreatments (4 under light conditions and 4 in the dark to obtain respiration), with 100 specimens in each. The CT showed the highest net photosynthesis rate (PN = gross photosynthetic (PG) rate subtracted from respiration (RD)) of E. densa, with 59.3%, 32.8%, 13.0% higher compared to T1, T2 and T3, respectively. At T3 it was observed the highest mean respiration rate (RE) o E. densa and at T1, the lowest. Comparing PN with RD, we found that the photosynthetic process was, on average 3.5, 2.47, and 2.93 times higher in CT, T1, T2, and T3, respectively. The presence of glitter may have increased the reflectance of water, as it is a suspended particle and reflected light intensely, considering that it is a metal coated particle. Glitter reflects radiation, decreasing the light absorption process, compromising the use of underwater radiation by E. densa. The microplastic interferes with the absorption of light necessary for photosynthetic processes, reducing them, enabling an imbalance in the ecosystem.