Adaptations of bacteria to marine subsurface waters studied by temperature response

Abstract

The principal objective of this study was to determine if bacterial activities in marine subsurface waters (below the surface layer where primary productivity occurs) are dominated by a locally-adapted microbial flora or by bacteria which are better adapted to warmer surface-layer conditions. By measuring size fractionation and temperature response of leucine uptake in both surface layer and deeper samples, we concluded that while it is possible to find bacteria in the deeper water - presumably attached to sinking particles - with temperature responses similar to bacteria from the surface layer, they are responsible for only a small fraction of the total activity. Furthermore, the results support the conclusion that the turnover of dissolved organic matter in the subsurface layer is dominated by bacteria which are adapted somewhat to local temperature conditions.