PS 36-9 - Nutrient-dependent effect of anthropogenic microfibers on phytoplankton productivity

Abstract: Anthropogenic micropollutants like microplastics and other textile fibers are a growing concern in aquatic systems, and have been shown to have adverse effects on organisms throughout the food web from primary producers to vertebrates. Both synthetic microfibers and chemically treated natural fibers can be released by weathering textiles into aquatic systems, such as through washing machine wastewater. Given microfibers in freshwater lakes with increased anthropogenic activity may come in contact with other pollutants, like nitrogen and phosphorus, it is unclear how different microfibers might interact with other water quality parameters to affect phytoplankton growth. This study aimed to determine if introduced synthetic and natural anthropogenic fibers in the presence of various nutrients would impact freshwater phytoplankton productivity.



To examine the effects of microfibers on phytoplankton growth, we incubated lake water for eight days with additions of polyester and/or cotton microfibers (no additions, +polyester, +cotton, and +polyester and cotton). To further examine how nutrient limitations may interact with microfibers to affect phytoplankton growth, each microfiber treatment was also subject to additions of nitrogen (N) and/or phosphorus (P) (no addition, +N, +P, +N and P). At the conclusion of the incubation, we used chlorophyll a analysis as a proxy for phytoplankton biomass and trichromatic chlorophyll analysis to infer growth differences between phytoplankton taxa. We found significantly lower chlorophyll a concentrations in treatments with cotton fibers under phosphorus additions, suggesting lower phytoplankton biomass. We also found significantly lower concentrations of chlorophyll c in all microfiber treatments under no nutrient additions. These findings suggest an interaction between microfibers and nutrient additions that may affect overall phytoplankton biomass, but also taxa-specific phytoplankton growth. These results indicate the need for further study to determine the mechanisms by which phytoplankton are affected by different microfibers, and how other water quality parameters, such as nutrients, may interact with microfibers to influence aquatic communities.