Primary Productivity-Phytoplankton Relationships, Hodgson Lake, Portage County, Ohio

Abstract

Primary productivity-phytoplankton relationships were studied for one year (1963-64) in Hodgson Lake, Portage County, Ohio. The lake was found to be a ''blue-green—diatom'' reservoir of moderate productivity, but containing a large phytoplankton standing crop, dominated by the cyanophycean, Oscillatoria rubescens Decandole. Average cell volumes ranged from 1.4 mm3 liter-1 in September to approximately 88.6 mm3liter-1 in June, over 80 percent of which were 0. rubescens. Diatoms, including Cyclotella sp, Fragilaria sp. Asterionella formosa Hass, and Synedra delicatissima W. Sm., usually accounted for <10 percent of the total cell volume. Photosynthesis ranged from 4-5 mgC m-2 day-1 during the winter to approximately 2600-2700 mgC m-2 day-1 in June and October, with an annual mean of 847.5 mgC m~2 day"1. Photosynthesis per unit cell volume ranged from <1ugC day-1 mm-3 during the winter to 172.8 gC day-1 mm-3 in October, averaging 10.5 ugC day-1 mm-3 annually.