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Two years of investigations into phytoplankton and ecosystem dynamics in Lake Fulmor, CA using the N

Parameters: Active Fluorescence

Phytoplankton communities in lake ecosystems

  • Communities may be diverse or dominated by one or few species

  • The environment that phytoplankton experience is highly dependent on water stratification and flow

  • These parameters are highly variable on both spatial & temporal scales

  • Blooms of potentially toxic cyanobacteria & overall eutrophication an important issue for lake ecosystems

  • Light extremes & nutrient stress may alter the photosynthetic efficiency of phytoplankton, which is still poorly understood.

Lake Fulmor, San Jacinto Mountains, CA

Subalpine lake, altitude ~5000ft. Maximum depth: 6m Low flow but relatively strong discrete wind events Observed surface scum formation during wind events

Problem Description: Networked Aquatic Microbial Observing System (NAMOS)

Combined mobile & static components for estimating phytoplankton biomass & water structure

  • Temperature sensors provide information on water column stratification

  • surface - 2.5 meters

  • Chlorophyll fluorometers estimate phytoplankton biomass near the surface

  • Meteorological instrumentation, including wind speed & direction which influence surface water currents & temperature.

  • Active fluorometer & NIMS RD provided additional sensor information (pH, DO)

  • Discrete samples for nutrients, microscopical analysis, toxin & molecular analyses.

Proposed Solution: Diverse Sensors and Techniques to Characterize a Dynamic Community

  • Fluorometer data (blue line) and Phytoflash yield (green line) from August 2006.

  • Phytoflash fluorometer (Turner Designs) uses ‘active fluorescence’ to estimate efficiency of light absorption in photosynthesis.

  • Data shows lower efficiency:

  • during night hours, when there is no light for photosynthesis

  • at mid-day, when light is supra-optimal & can cause cellular damage

Thermal Stratification increases throughout the 2006 season, with implications for the mixing regime & phytoplankton distribution.

We observed a large chlorophyll peak at 3m depth in August 2006. • Isolated small green flagellate from samples

Author: Beth Stauffer, Stefanie Moorthi, David Caron, Gaurav Sukhatme, Carl Oberg, Bin Zhang, Amit Dhariwal, Arvind Menezes-Pereira

Institution: University of Southern California, Department of Biological Sciences, Computer Science Department

Location: Lake Fulmor, CA

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