plankt.oxfordjournals.org Featured Article Downloaded fromhttp://plankt.oxfordjournals.org/at McGill University Libraries on February 17, 2014 Journal of Plankton Research 3. Plankton Res. (2013) 35(3): 485-503. First published online January 21, 2013 doi:10.1093/plankt/fbt002 Effect of East Asian aerosol enrichment on microbial community composition in the South China Sea CUI GUO, HONGMEI JING, LIANGLIANG KONG AND HONGBIN LIU* DIVISION OF LIFE SCIENCE, THE HONG KONG UNIVERSITY OF SCIENCE AND TECHNOLOGY, CLEAR WATER BAY, KOWLOON, HONG KONG SAR, CHINA *CORRESPONDING AUTHOR: liuhb@ust.hk Received October 15, 2012; accepted December 31, 2012 Corresponding editor: John Dolan East Asian aerosol has been regarded as an increasingly important nutrient source in the Northwest Pacific region due to intensifying human activities in the last decades. However, its effects on bacterial communities, an important component of the marine microbial food web and biogeochemical cycles, have been little studied. In our study, two types of aerosol enrichment microcosm experiments were conducted in the oligotrophic South China Sea by adding the aerosol initial- ly or daily. Our results showed that the potential stimulus of bacteria by aerosol enrichment was likely masked by a more intense grazing pressure in these treat- ments. Distinct responses of various bacterial phylogenetic groups, including Actinobacteria, Cyanobacteria, Alphaproteobacteria and Gammaproteobacteria, were revealed by denaturing gradient gel electrophoresis analysis. High aerosol addition resulted in a decrease in autotrophic picocyanobacteria abundance, but no significant com- position change was observed. Such responses of microbial abundance and com- position could be directly triggered by the input of aerosol-derived organic or inorganic components and further shaped by the changes in the phytoplankton community structure or differentiated mortality loss caused by enhanced protist grazing, which may have implications for oceanic carbon dynamics under future scenarios of increasing atmospheric deposition. KEYWORDS: East Asian aerosol; heterotrophic bacteria; abundance and community composition; picocyanobacteria; South China Sea available online at www.plankt.oxfordjournals.org C The Author 2013. Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com