海洋

Rates of respiration and nitrogen excretion of zooplankton, Sinocalanus tenellus (Kikuchi) and Tigriopus japonicus Mori, were measured for various starvation periods. The percentages of carbon, nitrogen and hydrogen present in animals have been also determined. All these rates decreased with starvation. Almost all excretory nitrogen of Sinocalanus were in the form of NH_4-N, but Tigriopus excreted 20-45% of total excretory nitrogen, as the form of non NH_4-N. The ratios of non NH_4-N to the total nitrogen excreted became higher with starvation. Body nitrogen: body carbon ratios were nearly constant through the starved conditions (C: N ratio ca. 3.8 for Sinocalanus, ca. 4.0 for Tigriopus). It is appeared that these animals have already been in the basic metabolic state at the 1st day of experiment, judging from the value of atomic ratio of respiratory rate to excretory rate of nitrogen (0: N ratio for Sinocalanus ca. 11.3, for Tigriopus ca. 7.7). Sinocalanus excreted daily 7% and 6.5%, Tigriopus 4.7% and 6.4% of body nitrogen and body carbon respectively in their basic metabolic state. The daily animal requirements for food organisms were estimated from the quantities of carbon and nitrogen excreted and those in the food organisms, resulting that Sinocalanus required 2 × 10^4 – 5 × 10^4 diatom cells ／ animal ／ day and Tigriopus 3 × 10^2 － 7 × 10^2.