Size-fractionated plankton respiration and phytoplankton production rates in shrimp culture ecosystems

Size-fractionated plankton respiration and phytoplankton production rates in shrimp culture ecosystems were studied with five experimental enclosures from June to August 1997 in the shrimp farm of the Huanghai Fisheris Corporation in Shandong Province,China.The results show that(1)the average respiration rates of the plankton of micro-,nano- and pico-plankton are 0.07, 0.38 and 0.31 mg/(dm 3·d), which are 9%, 50% and 41% of the sum of each sized plankton.The phytoplankton production rates of micro-,nano- and pico-phytoplankton are 0.04,1.26 and 0.15 mg/(dm 3·d), which are 3%, 87% and 10% of the sum of each sized phytoplankton.The ratios of the respiration rates of different sized plankton to corresponding sized phytoplankton production rates are: micro-,175%;nano-,30%;pico-,207%.(2) the respiration rates of zooplankton of micro-and pico-(containing bacteria) are higher than those of the corresponding sized phytoplankton, while the respiration rate of nano-phytoplankton is higher than that of nano-zooplankton.The sequence of the respiration rates of different sized phytoplankton is nano-greater than pico-greater than micro-,and the order of the respiration rates of different sized zooplankton is pico-(containing bacteria)greater than nano- greater than micro-.