Quantifying and Predicting Microscale Patchiness of Plankton

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Over the past decade the PI of this project has developed planar laser imaging fluorometery (PLIF) systems that provide two-dimensional images of plankton, undisturbed, in situ. He has collected over 10 Tb of data containing vertical profiles of the number, size, and spatial distribution of phytoplankton, zooplankton, and aggregates in the ocean off Southern California. These images are complemented by extensive coincident auxiliary measurements of physical and chemical properties of the environment. This project will use the archived data to quantify the spatial distribution patterns of individual plankters spanning scales from 95 um to 55 m in situ, and relate those distributions to the underlying turbulent structures, density gradients, vertical shear, and chemical gradients. The analyses will allow us to resolve the scales and dynamics that govern the change in plankton distributions from random at small scales to persistent gradients and layers at larger scales, as well as the relationship of particle concentrations to turbulent structures (vorticity and strain). These analyses will yield a more quantitative understanding of the physical-chemical-biological interactions that structure planktonic communities, the foraging environment for zooplankton, and the processes controlling local diversity of the plankton community. Combining the data analyses with models of the underlying dynamics will enhance our ability to predict the spatial and temporal patchiness of planktonic distributions, and increase our understanding of the factors influencing trophic interactions and biogeochemical cycling in the marine environment.Broader Impacts:This project will advance discovery and understanding while promoting teaching and learning by incorporating elements of the proposed research into high-school and graduate courses. The PI and graduate student will mentor REU students, and involve them in the data analyses. The proposed work will form the core of the PhD thesis of an interdisciplinary female graduate student. They will broaden the participation of underrepresented groups by teaching a summer course through to underrepresented high-school students, and by mentoring and officiating for the National Ocean Sciences Bowl. They will enhance research infrastructure by adding value to data collected in collaboration with academia, industry and international partners, representing multiple scientific disciplines. They will broadly disseminate our results in conference presentations at and publications, as well as work with journalists and institutional public information officers. Benefits to society will be realized through improved understanding of important of processes in the marine ecosystem, ultimately yielding greater understanding of oceanic response to climate change. Indeed, the quantification of the importance of microscale patches to ecosystem functioning and biogeochemical fluxes may help us understand their role in regulating climate and moderating anthropogenic perturbations.