Microbial pollutants like bacteria and viruses reduce the full beneficial use of water resources and negatively affecting human health, the environment, and the economy. Natural treatment systems like treatment wetlands or retention ponds can be a low-cost and sustainable option to improve water quality while providing natural habitat and aesthetic benefits. However, the reliability and efficiency of these systems to remove microbial pollutants can vary widely, which limits their widespread deployment. The ultimate goal of this research is to improve water quality through the novel use of zooplankton in natural treatment systems, providing increased water security and enhanced environmental aesthetics. In addition to broader societal impacts, this research will be conducted at a women's liberal arts college that has a long-standing commitment to recruiting and retaining minority and first-generation students. This project will involve undergraduate students in scientific research and provide opportunities for these students to present their results at conferences, contribute to journal publications, and participate in educational outreach events.
Microbial pollutants are a significant contributor to poor water quality, and gaining a mechanistic understanding of different inactivation or removal mechanisms of these pollutants is important to predict the performance of natural treatment systems. The reduction of bacteria and viruses through variations in water chemistry, sedimentation, and sunlight inactivation is well documented, but the mechanisms and contributions of removal via predation by organisms of higher trophic level is not understood. Current models predicting performance of natural systems to remove microbial pollutants focus on sunlight inactivation and neglect to quantify biotic processes such as zooplankton filter feeding. Hence, developing methods to enhance the performance of these systems, as well as improving current inactivation models to predict performance due to predation, is necessary. This research will explore the efficacy of zooplankton to remove microbial pollutants in natural systems. Zooplankton can remove suspended organic particulate matter, including bacteria, from the water column, but little is known about the effectiveness of utilizing zooplankton to improve water quality in natural systems. The main objectives this research are: 1) to quantify the ability of zooplankton to remove microbial pollutants at various environmentally relevant conditions in natural waters; 2) to understand the factors that impact uptake rates; and 3) to use this information to develop a quantitative model that relates zooplankton uptake rates to relevant environmental variables. These objectives will be accomplished through a series of laboratory and field-based feeding experiments using different zooplankton assemblages and varying microbial pollutants, including environmentally isolated Escherichia coli and F+ RNA coliphages. The outcomes from this research will be used to address important knowledge gaps of how conditions in natural systems impact zooplankton feeding. Zooplankton filtration rates have not been measured in complex environments with varying types of particulate matter, and the viability of microbial pollutants after ingestion is uncertain. In addition to addressing these knowledge gaps, the research will result in a model that can be used to predict the variation of zooplankton clearance rates of target pollutants based on seasonal changes in seston characteristics. This model will be widely applicable and could help inform decision makers about the optimal conditions to promote zooplankton filter feeding.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
