JPR Advance Access originally published online on January 24, 2008
Journal of Plankton Research 2008 30(3):299-309; doi:10.1093/plankt/fbn001
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Productivity and grazing impact of Oikopleura dioica (Tunicata, Appendicularia) in Tokyo Bay
1 Department of Ocean Sciences, Tokyo University of Marine Science and Technology, 4-5-7 Konan, Minato-ku, Tokyo 108-8477, Japan 2 Department of Environmental Simulation, Institute for Environmental Sciences, Ienomae 1-7, Rokkasho-mura, Kamikita-gun, Aomori 039-3212, Japan 3 Louisiana Universities Marine Consortium, 8124 Highway 56, Chauvin, LA 70344, USA
* CORRESPONDING AUTHOR: rsato{at}ies.or.jp
Received on November 7, 2007; accepted on January 2, 2008
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Abstract |
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To estimate the productivity and grazing impact of a common appendicularian species Oikopleura dioica in Tokyo Bay, monthly observations on its abundance and vertical distribution were conducted during 2000. The abundance peaked in February and October, but was low during summer. Seasonal fluctuations in productivity were similar to those of the abundance, with maximum values of 92, 134 and 508 mg C m–2 day–1 for somatic, new house and discarded house productivity in October and 206 mg C m–2 day–1 for fecal pellet productivity in February, respectively. The averaged biomass of O. dioica was only 2.5% of that of copepods; however, the secondary productivity of the former corresponded to 12.4% of the latter. Daily grazing impact on particulate organic carbon ranged from 0.05% to 5%, which is close to the impact by copepods. These results imply that in Tokyo Bay, where small copepods and jellyfish are abundant, O. dioica is an important component of the ecosystem because it bridges between small primary producers and higher consumers.
Communicating editor: Roger Harris