Effects of stratification depth and dissolved organic matter on brackish bacterioplankton communities

Abstract

Bacterioplankton growth is often directly or indirectly controlled by external energy subsidies via organic matter inputs or solar radiation. We carried out a mesocosm experiment to assess how bacterioplankton communities responded to elevated levels of dissolved organic matter (DOM) and experimentally controlled stratification depth. The month-long experiment consisted of 2500 l mesocosms subjected to 4 experimental manipulations in triplicate: the stratification depth was set to either 1.5 or 3.5 m, with or without experimental addition of ambient levels of chromophoric DOM. DOM addition had a significant effect on bacterial community composition as assessed by terminal restriction fragment length polymorphism of amplified 16S rRNA genes. In contrast, there were no effects of the DOM amendment on bacterial biomass or production. Mixing depth and the coupled effective light climate in the photic zone also had a significant effect on bacterial community composition. Furthermore, shallow mixing depth was associated with enhanced primary production, whereas DOM addition had a negative effect on phyto plankton biomass and productivity. Our results suggest that bacterial community composition is coupled to primary production under the studied coastal nutrient regime, and point to a key role of DOM quality in controlling bacterioplankton communities.

Keywords

Bacterial community composition; Dissolved organic matter; Stratification depth; Mesocosm; Brackish; Phytoplankton

Published in

Marine Ecology Progress Series
2012, volume: 453, pages: 37-48
Publisher: INTER-RESEARCH

SLU Authors

• Weyhenmeyer, Gesa

  • Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences
    

Global goals (SDG)

SDG14 Life below water

UKÄ Subject classification

Environmental Sciences
Other Biological Topics
Ecology

Publication identifier

• DOI: https://doi.org/10.3354/meps09634

Permanent link to this page (URI)

https://res.slu.se/id/publ/45149