Ariel Friel, Ph.D. Candidate

Department of Life Sciences

Desert Spring Prokaryotes and Benthic Macroinvertebrates: Geological and Ecological Controls

Committee Members:

• Dr. Brian Hedlund, Advisory Committee Chair
• Dr. Helen Wing, Advisory Committee Member
• Dr. Jef Jaeger, Advisory Committee Member
• Dr. Duane Moser, Advisory Committee Member
• Dr. Laura Rademacher, External Advisory Committee Member
• Dr. Elisabeth Hausrath, Graduate College Representative

Abstract

Desert springs are aquatic oases, being considered among the most diverse and imperiled ecosystems on Earth. Despite the ecological significance and threatened status of desert springs, few studies have surveyed the microorganisms in these systems or their interactions with other community members. To address these gaps, we conducted detailed ecohydrogeological assessments of prokaryotic and benthic macroinvertebrate (BMI) communities in desert springs across the southern hydrographic Great Basin. To start, I will present the first-ever, regional-scale 16S rRNA gene amplicon survey of the desert spring microbiome. This survey uncovered strong differentiation in the diversity, composition, and putative functional profiles of the desert spring microbiome corresponding to the three major spring recharge groups ('local springs', 'regional springs', and 'saline springs'). We found evidence that the biogeography of the desert spring microbiome is shaped by a combination of environmental filtering and dispersal limitation. Further characterization by comparison to the Earth Microbiome Project revealed that desert springs host some of the most diverse microbial communities on Earth and approximately one-third of the regional desert spring microbiome is endemic. Next, I will describe the local-scale and regional-scale controls on the synecology of benthic prokaryotic and BMI communities in desert springs. I will also discuss potential functional interactions occurring between these communities in the spring benthos food web. Benthic prokaryotic and BMI communities and their functional interactions are strongly influenced by spring recharge flow paths at both scales. At the local scale, subtle geochemical differences imparted during the weathering of distinct geological units are the dominant control. At the regional scale, broad physicochemical differences related to the residence time of spring recharge are the dominant control. Ultimately, my research establishes an ecological baseline of the regional desert spring microbiome and its functional interactions with other community members.