BRC-BIO: Structure and functioning of microbial plankton under coastal hypoxia

Hofstra University, Hempstead NY

Investigators

Abstract

Periodic coastal hypoxia (low dissolved oxygen in the water and sediments) has major ecological consequences, including some negative effects on marine fauna and ecosystem services. Worldwide, coastal hypoxia is caused by both natural and human human-induced environmental change. Higher summer temperatures and increased inputs of nitrogen pollutants exacerbate microbial processes that consume dissolved oxygen, increasing the frequency and severity of hypoxia events. Biotic and abiotic interactions within these microbial communities are rarely studied simultaneously, which limits our understanding of the feedbacks between microbial processes and hypoxia. This project will investigate the relationships among a broad spectrum of planktonic microorganisms (bacteria, archaea, protists and microscopic animals) and abiotic variables (e.g., temperature, oxygen, N compounds) in the waters of an estuarine embayment in Long Island Sound, NY, that suffers hypoxia every summer. The project will quantify communities, metabolism, and predator-prey interaction across the microbial community. Results will inform scientists, environmental partners, and the public about the root causes of hypoxia, at a time when coastal hypoxia is increasing. The project has a strong educational component, including research experiences for high-school and undergraduate students. The students will be trained in microscopy, DNA sequencing, and bioinformatics. Training activities will increase participation of underrepresented minorities and will focus on marketable skills that empower and help retain individuals in higher education and STEM jobs. The overarching goal of this project is to launch a multi-annual research program investigating interactions between microbial plankton and deoxygenation in human-impacted coastal waters. The project will fill a key knowledge gap by simultaneously examining communities of bacteria, archaea, and microbial eukaryotes. Microbial processes lead to, and are influenced by, coastal hypoxia. This project will use the summer progression of deoxygenation in a eutrophic estuarine embayment as a “natural laboratory” to quantify changes in microbial community structure and functioning in hypoxia versus normoxia. Methods will combine field work, cell counts (microscopy, flow cytometry), DNA sequencing (metabarcoding, shotgun metagenomics) and experimental quantifications of bacterioplankton and phytoplankton consumption by microeukaryotes. Environmental data, microbial abundances, taxonomic and functional genetic profiles, and prey consumption rates will be used to test hypotheses on changes in feeding interactions and metabolic potential as summer progresses. Results will improve the understanding of microbial effects on (and responses to) hypoxia, and will help predicting trophic and biogeochemical shifts under current and future dissolved oxygen levels in coastal waters. 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.