Abstract: To reveal the relationships between virioplankton abundance and environmental factors in sea cucumber (Apostichopus japonicus) culture pond ecosystem, the virioplankton abundance in an A. japonicusculture pond of Xietun near Dalian City was determined from March to November 2008. In the meantime, the environmental factors such as water temperature, pH, dissolved oxygen, salinity, chlorophyll a, chemical oxygen demand, inorganic nitrogen and phosphorus, and heterotrophic bacterioplankton were monitored, with the relationships between the virioplankton abundance and these environmental factors analyzed. In the A. japonicus culture pond, the virioplankton abundance was the highest (18.2×10¹⁰ VLPs·L^-1) in April and the lowest (1.31×10¹⁰ VLPs·L^-1) in November, with an average of 8.32×10¹⁰ VLPs·L^-1; while in outer sea, the virioplankton abundance was the highest (12.6×10¹⁰ VLPs·L^-1) in April and the lowest (2.02×10¹⁰ VLPs·L^-1) in June, with an average of 6.45×10¹⁰ VLPs·L^-1. The main environmental factors affecting the virioplankton abundance in the A. japonicus culture pond were nutrients, water temperature, pH, and salinity; while those affecting the abundance in outer sea were chlorophyll a and heterotrophic bacterioplankton.

Key words: Qinling Moutains, Pinus armandi, Community characteristics, Phytogeographial elements, Physiognomic characteristics, Spatial distribution pattern