TY - JOUR
T1 - Effects of increasing atmospheric CO2 on the marine phytoplankton and bacterial metabolism during a bloom
T2 - a coastal mesocosm study
AU - Huang, Yibin
AU - Liu, Xin
AU - Laws, Edward A.
AU - Chen, Bingzhang
AU - Li, Yan
AU - Xie, Yuyuan
AU - Wu, Yaping
AU - Gao, Kunshan
AU - Huang, Bangqin
PY - 2018/8/15
Y1 - 2018/8/15
N2 - Increases of atmospheric CO2 concentrations due to human activity and associated effects on aquatic eco- systems are recognized as an environmental issue at a global scale. Growing attention is being paid to CO2 enrichment effects under multiple stresses or fluctuating environmental conditions in order to extrap- olate from laboratory-scale experiments to natural systems. We carried out a mesocosm experiment in coastal water with an assemblage of three model phytoplankton species and their associated bacteria under the influence of elevated CO2 concentrations. Net community production and the metabolic charac- teristics of the phytoplankton and bacteria were monitored to elucidate how these organisms responded to CO2 enrichment during the course of the algal bloom. We found that CO2 enrichment (1000 μatm) signifi- cantly enhanced gross primary production and the ratio of photosynthesis to chlorophyll a by approxi- mately 38% and 39%, respectively, during the early stationary phase of the algal bloom. Although there were few effects on bulk bacterial production, a significant decrease of bulk bacterial respiration (up to 31%) at elevated CO2 resulted in an increase of bacterial growth efficiency. The implication is that an eleva- tion of CO2 concentrations leads to a reduction of bacterial carbon demand and enhances carbon transfer efficiency through the microbial loop, with a greater proportion of fixed carbon being allocated to bacterial biomass and less being lost as CO2. The contemporaneous responses of phytoplankton and bacterial metabolism to CO2 enrichment increased net community production by about 45%, an increase that would have profound implications for the carbon cycle in coastal marine ecosystems.
AB - Increases of atmospheric CO2 concentrations due to human activity and associated effects on aquatic eco- systems are recognized as an environmental issue at a global scale. Growing attention is being paid to CO2 enrichment effects under multiple stresses or fluctuating environmental conditions in order to extrap- olate from laboratory-scale experiments to natural systems. We carried out a mesocosm experiment in coastal water with an assemblage of three model phytoplankton species and their associated bacteria under the influence of elevated CO2 concentrations. Net community production and the metabolic charac- teristics of the phytoplankton and bacteria were monitored to elucidate how these organisms responded to CO2 enrichment during the course of the algal bloom. We found that CO2 enrichment (1000 μatm) signifi- cantly enhanced gross primary production and the ratio of photosynthesis to chlorophyll a by approxi- mately 38% and 39%, respectively, during the early stationary phase of the algal bloom. Although there were few effects on bulk bacterial production, a significant decrease of bulk bacterial respiration (up to 31%) at elevated CO2 resulted in an increase of bacterial growth efficiency. The implication is that an eleva- tion of CO2 concentrations leads to a reduction of bacterial carbon demand and enhances carbon transfer efficiency through the microbial loop, with a greater proportion of fixed carbon being allocated to bacterial biomass and less being lost as CO2. The contemporaneous responses of phytoplankton and bacterial metabolism to CO2 enrichment increased net community production by about 45%, an increase that would have profound implications for the carbon cycle in coastal marine ecosystems.
KW - mesocosm scale
KW - gross primary production
KW - bacterial respiration
KW - bacterial growth efficiency
KW - net community production
U2 - 10.1016/j.scitotenv.2018.03.222
DO - 10.1016/j.scitotenv.2018.03.222
M3 - Article
VL - 633
SP - 618
EP - 629
JO - Science of the Total Environment
JF - Science of the Total Environment
SN - 0048-9697
ER -