Respiration rates of bathyal meiobenthos collected using a deep-sea submersible SHINKAI 2000

Abstract

Respiration rates of deep-sea meiofaunal nematodes, polychaetes, aplacophorans and copepods were measured individually using a Cartesian diver technique. The organisms were extracted from sediments collected using a deep-sea submersible SHINKAI 2000 in the area off Sanriku, northeastern Japan (depth = 1500 m), and in Suruga Bay, Central Japan (depth = 1350 m). In spite of rapid decompression, animals respired actively at cool (5°C) condition close to the ambient temperature. A significant relationship was found between the rate of respiration (R) and body volume (V) with an equation, log₁₀R = log₁₀a + blog₁₀V, for nematodes and other meiofaunal taxa. In both equations, b was not statistically different (t-test) from 0.75, the value commonly ascribed to other organisms. The metabolic intensity (MI) was calculated as the value of log₁₀a at V = 1 and b = 0.75 to compare the respiration rates between different species under standard conditions. Within deep-sea meiofauna, the mean MI of nematodes (−0.059) was higher than that of other groups (polychaetes: −0.55; aplacophorans: −0.46; copepods: −0.67). Nematode MI was not related to feeding type nor to water depth. In the case of copepods and polychaetes, no difference was found with reported results for shallow-water species.