Phytoplankton Community Composition in the Eastern Subarctic Pacific Derived from Hyperspectral Optics
Abstract. We evaluate the utility of hyperspectral particulate absorption data to characterize phytoplankton community structure in the eastern Subarctic Pacific Ocean. Relative to existing algorithms based solely on Chlorophyll-a concentrations (Chla), improved taxonomic classification (validated with pigment-based data) was obtained by including Principal Components Analysis of hyperspectral absorption data. Multiple linear regression of hyperspectral absorption data yielded better taxonomic classification, particularly for estimates of haptophyte biomass. In addition, size-fractionated hyperspectral measurements were used to determine the dominant phytoplankton size of the phytoplankton community. Using high-frequency ship-board optical data, we examined the spatial patterns in phytoplankton taxonomic abundance in coastal and offshore waters around Vancouver Island, British Columbia. Results from this analysis were consistent with expectations based on previous low-resolution sampling, demonstrating expected seasonal succession of different phytoplankton groups, and significant variability in coastal phytoplankton taxonomy associated with dominant hydrographic features. In contrast, much less spatial and temporal variability was observed in offshore waters. Derived patterns in phytoplankton taxonomy were linked to observed patterns in surface water biogeochemical properties, notably the distribution of dimethyl sulfide (DMS) and dimethylsulfoniopropionate (DMSP) to Chla ratios. Our results highlight the potential for shipboard hyperspectral absorption data to describe phytoplankton community composition and ancillary biogeochemical variables.
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