Impact of elevated pCO2 on heterotrophic bacterioplankton: a mesocosm experiment
The rapid rise in anthropogenic atmospheric carbon dioxide (CO2) and the subsequent acidification of the world oceans has increased the need to determine if these changes will seriously and adversely impact the microbial food web and its constituents. A mesocosm study was conducted to test the effects of elevated partial pressure CO2 (pCO2) on the community composition and abundance of bacterioplankton. Three levels of pCO2 were established in triplicate: 650 μatm (Control), 1250 μatm (High), and 1250 μatm allowed to drift (Drift). Initial light levels were reduced to slow biological processes and were returned to ambient conditions on T10. Results of bacterial abundance were statistically significant between treatments with the High and Drift treatments showing the lowest abundance. Community composition was shown to change temporally with distinct shifts in structure from T0 to T13 to T21. There was no change in community species composition among the treatments. Study indicates elevated levels of pCO2 suppresses abundance of bacterioplankton without a corresponding change in community structure.