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Enclosure experiment on the control mechanism of planktonic bacterial standing stock
Author(s) -
Kato Kenji,
Oh Suwan,
Yamamoto Hiroyuki,
Hanazato Takayuki,
Yasuda Ikuko,
Otuki Akira,
Takahashi Masayuki
Publication year - 1992
Publication title -
ecological research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.628
H-Index - 68
eISSN - 1440-1703
pISSN - 0912-3814
DOI - 10.1007/bf02347095
Subject(s) - bacteria , phytoplankton , enclosure , plankton , water column , biology , environmental science , grazing , stock (firearms) , ecology , zoology , nutrient , mechanical engineering , telecommunications , genetics , computer science , engineering
In order to understand the control mechanisms of a large, stable bacterial standing stock, enclosure experiments were conducted in a eutrophic lake, where both bacterial productivity and grazing pressure were very high. Total bacterial number in the different enclosures ranged from 1.2 to 2.7×10 7 cells mL −1 throughout the experiment. The average bacterial cell production rate estimated from a grazer eliminating experiment was 6.3×10 5 cells mL −1 h −1 . Difference in the bacterial cell production rate between shaded and unshaded enclosures was not apparent. Bacteria showed a reduction in standing stock of only about 25–30% even after the supply of light was cut to 1%. Bacteria in the shaded enclosures then recovered their production rate in the first 12 days of perturbation. Grazing pressure in the shaded enclosures was not less than that for the control. Thus, it was considered a control mechanism of bacterial stable standing stock that the bacteria shifted their organic substrate from extracellular dissolved organic carbon freshly released from phytoplankton to that already stocked in the water column, though it is not known whether the dominant bacteria were the same.