Oxygen Minimum Zone Variability and Ecosystem Responses in the Arabian Sea during the Last Glacial-interglacial Cycle:A Paired Paleogenomic and (Isotopic) Lipid Biomarker Approach

Woods Hole Oceanographic Institution, Woods Hole MA

Investigators

Abstract

Available monitoring data suggest that mid-water oxygen depletion regions, or Oxygen Minimum Zones (OMZs), are expanding in the world's oceans in the context of global warming. As OMZs expand, marine ecosystems are expected to experience disturbances in the structure and dynamics of food webs and in the production of greenhouse gasses, with resulting feedbacks on the climate system. The northern Arabian Sea has an exceptionally widespread OMZ characterized by a strong seasonal variability of monsoonal upwelling and high algal primary productivity. Although sediment records from the region have been extensively studied to reconstruct causes, timing, and duration of OMZ extent since the last glacial-interglacial cycle, it remains entirely unknown how long-term changes in OMZ variability has impacted past ecosystems and food webs in the Arabian Sea. This research, conducted by a team of scientists from the Woods Hole Oceanographic Institution (WHOI), uses ultra-high-throughput sequencing of sedimentary ancient DNA signatures (i.e., the "paleome") to reconstruct past populations of marine organisms. Advanced bioinformatics and statistical tools will be used to identify species that were most strongly impacted by long-term fluctuations in OMZ strength during key climate intervals over the last 80,000 years. Parallel changes in climate and environmental conditions will be reconstructed using (molecular) geochemical techniques. For this project the research team will use a continuous, undisturbed and radiocarbon-dated sediment record that was recently obtained from the center of the OMZ on the continental slope northwest of the Indus Canyon. The high-resolution ancient DNA records will greatly help to refine past environmental and climate interpretations in the monsoon-impacted northeastern Arabian Sea area. This study will provide insights into how ecosystems will respond to long-term periods of OMZ conditions and how these ecosystems adapt after the return of a well-mixed and oxygenated water column. Bioinformatics and numerical modeling analyses will be carried out in collaboration with a researcher from the University of Glasgow in the United Kingdom. The project will provide educational opportunities for a graduate student enrolled in the MIT/WHOI joint program in oceanography and for two undergraduate students, who will be recruited through WHOI's Summer Student Fellowship and Minority Fellowship programs. In addition, results and bioinformatics approaches from this study will be implemented in a lecture during the popular annual course "Strategies and Techniques for Analyzing Microbial Population Structure (STAMPS)" at the Marine Biology Laboratory (MBL) in Woods Hole.