Seiji Furukawa

Impacts of CO2 on Microbial Communities in a Mesocosm experiment

Publisher Summary Ocean sequestration of CO 2 is one of the feasible options to mitigate atmospheric CO 2 increase. On the basis of detailed investigations to date, it has been widely recognized that the CO 2 sequestration in the ocean is a promising option from the points of view of its capacity, economy and effectiveness. The impacts of CO 2 ocean sequestration on microbial communities and their metabolism are of great concern because they play an important role in the biogeochemical cycles. A mesocosm experiment was conducted to study the responses of marine microbial communities to different concentrations of CO 2 . Seawater was delivered to four tanks on land from the offshore, using a tube pump. Four CO 2 conditions of experimental ecosystems were formed by CO 2 enriched air under dark conditions. Chemical and biological parameters were analyzed to evaluate the impacts of CO 2 on the microbial communities. The biomass of each tank was not affected considerably by the different CO 2 conditions, but the potential activities of ectoenzyme were decreased under high concentration of CO 2 . The effects of CO 2 on bacterial communities were also confirmed using molecular biological methods. To clarify the impact of CO 2 on marine ecosystem, experiment should be planned to take interactions of variety of marine species into account. Bacteria play important role in ecosystem of mid-depth ocean where CO 2 is assumed to be injected. Bacteria are not only the major decomposers of organic material in the ocean but also the most important potential genetic resource. Further experiments are needed to generalize the impacts of CO 2 on the marine ecosystem.

Effects of CO2 on deep-sea floor microbial communities

Publisher Summary It has been widely recognized that a substantial rise of carbon dioxide (CO2) concentration in the atmosphere causes global climate change. In an effort to reduce the future atmospheric CO2, some technological mitigation strategies have been proposed. On the basis of detailed investigations to, it has been recognized that the CO2 sequestration in the ocean is one of the promising option from the points of view of its capacity, economy, and effectiveness. Benthic chamber experiment is conducted to investigate the impact of CO2 injection on deep-sea microbial ecosystem. In the experiment, the impact of CO2 and CO2-induced pH change on deep-sea floor microbial communities are investigated to determine the ecological effects by CO2 ocean sequestration. Microbial communities are characterized by using cultivation-independent molecular techniques—PCR (polymerase chain reaction)-based denaturing gradient gel electrophoresis (DOGE). A shift in community composition caused by CO2 enrichment is observed in sea-floor surface. To determine relationships among the community fingerprints, similarities are calculated and unweighted pair group clustering method with arithmetic averages is used to create a dendrogram describing pattern similarities.