Patchiness, collapse and succession of a cyanobacterial bloom evaluated by synoptic sampling and remote sensing

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Abstract
Spatial patchiness and collapse of the cyanobacterium, Nodularia spumigena , were evaluated in saline Pyramid Lake, Nevada, by two synoptic ground surveys and Landsat remote sensing. Horizontal variation of surface water chlorophyll a during the first survey ranged from 3.6 to 9790 mg m −3 and Nodularia biovolume was between 416×10 3 and 347×10 6 μm 3 ml −1 . Differences in spatial and temporal resolution between synoptic ground surveys (˜10m, hours) and Landsat imagery (80m, seconds) yielded a poor correlation when data were matched by common ground location. A regression model for estimating chlorophyll from Landsat radiance was developed by pairing equivalent frequencies from cumulative relative frequency distributions of both variables. Wind driven advection precipitated bloom collapse shortly after the first synoptic sample and Nodularia mineralization produced high epilimnetic ammonium concentrations. Ammonium, silica from fluvial sources, and density differences between river and lake water masses stimulated succession to a Chaetoceros elmorei bloom within 8 days of the first synoptic survey. The 16 day fly by interval of Landsat is too long to document such short-term bloom succession. Landsat imagery is most applicable for evaluating instantaneous, basin-scale horizontal patchiness and average lakewide chlorophyll concentrations, while frequent synoptic ground surveys yield more accurate estimates of meso- and micro-scale phytoplankton patchiness and species succession.