Naomi Levine is Gabilan assistant professor of biological sciences and earth sciences in the marine and environmental biology program at the USC Dana and David Dornsife College of Letters, Arts and Sciences. Her research focuses on understanding climate-ocean ecosystem interactions and the sensitivity of marine ecosystems to changes in climate.
Microscopic photosynthetic microbes (phytoplankton) are the base of the marine food web and responsible for approximately half of photosynthesis (oxygen production) on the planet. Understanding how climate change will impact marine microbes is critical for understanding both what our future planet will look like and how fish and other large organisms in the oceans might be impacted by climate change. Levine and her research group combine biological, chemical, and physical observations with ecosystem models in order to better understand the underlying mechanisms responsible for biogeochemical cycles in marine microbial ecosystems.
Scientists use computer models of the earth to predict what future climates will look like. However, because of computational costs, current computer models of global climate change are only able to represent a simplified version of the marine microbial food web. The Levine lab uses HPC resources to develop new modeling approaches that explicitly represent how microbial systems may respond to climate change.
To better understand how phytoplankton respond to the variability they experience in the ocean, Levine has developed a new ocean ecosystem model—the Spatially Heterogenous dynamic Plankton (SHiP) model—that represents subgrid cell, fine-scale, heterogeneity, and biophysical interactions. SHiP simulations run on the HPC cluster have demonstrated that these fine-scale ocean processes significantly alter ecosystem dynamics. This suggests that fine-scale dynamics such as the intermittent injection of nutrients, which are not captured by traditional models, may play an important role in large-scale (regional- and ocean basin-scale) biogeochemical cycling.
The Levine lab also uses HPC resources to study the impact of shifts in the composition of communities of heterotrophic bacteria (bacteria that consume organic carbon) biogeochemical cycling. This work has used observations from the USC-run San Pedro Ocean Time (SPOT) series site to integrate variable microbial remineralization into an ecosystem model. Through a collaboration with the National Center for Atmospheric Research (NCAR), this project will be expanded to investigate the global implications of a dynamic heterotrophic bacterial group on global carbon cycling.
Levine’s research is funded by the National Science Foundation (NSF), the National Aeronautics and Space Administration (NASA), the Rose Hills Foundation, and USC’s Women in Science and Engineering program. Levine is also an Alfred P. Sloan Research Fellowship recipient.
ABOVE: Using satellite data, the Levine lab estimates the patchiness of the ocean and then converts this into a disturbance rate (an estimate of the ‘weather’ in the ocean). A high disturbance rate means increased nutrient injections into the sunlit surface of the ocean. Levine’s team then uses the SHiP model to estimate the impact of these different disturbance rates on the phytoplankton growing in the surface of the ocean. The figure above shows model output for a high disturbance environment and a low disturbance environment.