The relationship of environmental variability to the spatial patterns of phytoplankton biomass in Lake Tahoe

Horizontal transects measuring phytoplankton biomass and temperaturewere made in Lake Tahoe in the nearshore epilimnion in 1976and 1977, near the deep chlorophyll maximum in midlake in 1977,and in the deep thermocline in 1976. Variance spectra from thesetransects indicate that large length scale patchiness dependson large-scale habitat variability, manifested as nitrate patchiness,caused by stream inflow in the nearshore epilimnion and by differentialtransport processes in the deeper water. When large-scale sourcesof habitat variability are absent, phytoplankton spatial patternsare not dominated by large-scale patches and are consistentwith a random distribution. No significant small-scale patchinesswas seen under any environmental conditions. ^*Current address: Jet Propulsion Laboratory, 183/501, 4800 OakGrove Drive, Pasadena, CA 91109, and Scripps Institution ofOceanography, A-002, University of California, La Jolla, CA92093 USA