Temperature Regulation of Bacterial Activity During the Spring Bloom in Newfoundland Coastal Waters

Abstract

While the spring phytoplankton bloom in Newfoundland coastal waters is in progress during April and May, at water temperatures between -1° and +2°C, bacterial growth and respiratory rates remain low. Microbial community respiration is not measurable at -0.2°C. Particulate materials that would be utilized by microorganisms in 2 to 3 days at 20° to 25°C require 11 days at 4°C and 18 days at -0.2°C. Thus, photosynthesis is active but microbial utilization of the products is suppressed. High secondary production in cold water may result from the low rate of microbial decomposition, enabling herbivores to utilize much of the primary production.