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Role of environment and hydrography in determining the picoplankton community structure of Sagami Bay, Japan

DRS at CSIR-National Institute of Oceanography

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Title Role of environment and hydrography in determining the picoplankton community structure of Sagami Bay, Japan
 
Creator Mitbavkar, S.
Saino, T.
Horimoto, N.
Kanda, J.
Ishimaru, T.
 
Subject picoplankton
community composition
ocean currents
Sagami Bay
 
Description Seasonal variations in the picoplankton community were investigated from June 2002 to March 2004 within the photic zone of Sagami Bay, Japan. The study area was mostly dominated by coastal waters during the warm period (mixed layer water temperature is greater than or equal to 18 degrees C). During the cold period (mixed layer water temperature is less than or equal to 18 degrees C), the water mass was characterized by low temperature and high saline waters indicative of the North Pacific Subtropical Mode Water (NPSTMW). Occasionally, a third type of water mass characterized by high temperature and low saline properties was observed, which could be evidence of the intrusion of warm Kuroshio waters. Synechococcus was the dominant picophytoplankton (5-28 x 10 sup(11) cells m sup(-2) followed by Prochlorococcus (1-5 x 10 sup(11) cells m sup(-2)) and picoeukaryotes during the warm period. Heterotrophic bacteria dominated the picoplankton community throughout the year, especially in the warm period. During the Kuroshio Current advection, cyanobacterial abundance was high whereas that of picoeukaryotes and heterotrophic bacteria was low. During the cold period, homogeneously distributed, lower picophytoplankton cell densities were observed. The dominance of Synechococcus in the warm period reflects the importance of high temperature, low salinity and high Photosynthetically Active Radiation (PAR) on its distribution. Cyanobacterial and heterotrophic bacterial abundance showed a positive correlation with temperature. Prochlorococcus and picoeukaryotes showed a positive correlation with nutrients. Picoeukaryotes were the major contributors to the picophytoplankton carbon biomass. The annual picophytoplankton contribution to the photosynthetic biomass was 32 plus or minus 4%. These observations suggest that the environmental conditions, combined with the seasonal variability in the source of the water mass, determines the community structure of picoplankton, which contributes substantially to the phytoplankton biomass and can play a very important role in the food web dynamics of Sagami Bay
 
Date 2009-12-18T09:04:03Z
2009-12-18T09:04:03Z
2009
 
Type Journal Article
 
Identifier Journal of Oceanography, vol.65(2); 195-208
http://drs.nio.org/drs/handle/2264/3476
 
Language en
 
Rights Copyright©The Oceanographic Society of Japan/TERRAPUB/Springer. All efforts have been made to respect the copyright to the best of our knowledge. Inadvertent omissions, if brought to our notice, stand for correction and withdrawal of document from this repository.
 
Publisher The Oceanographic Society of Japan