Preliminary Studies On Effects Of Different Factors On The Oxygen Consumption Rate Of Procephalothrix Simulus Iwata

The nemertean Procephalothrix simulus Iwata, a common intertidal nemertean in Qingdao, is selected to measure the effects of temperature, salinity, starvation, pressure, amputation and substratum on the oxygen consumption of it and its suffocation point.1. The effects of temperature on the oxygen consumption rateThe oxygen consumption rate is measured at seven temperature levels (5, 10, 15, 20, 25, 30 and 32°C) at the salinity of 31. The results show that the oxygen consumption rate rises significantly with increasing temperature varying from 0.15 mgO2g-1h-1 (5°C) to 3.09 mgO2g-1h-1 (32°C). The relationship can be expressed as: OCR (mgO2g-1h-1) =0.0077T1.674 (R2=0.9611, F=149.294, P<0.001), which shows there lies a power regression over this temperature range. Two peaks of Q10 value were observed in the temperature range of 10-15°С(8.26) and 30-32°С(6.26), and the lowest value was observed in the temperature range of 25-30°С(1.35).2. The effects of salinity on the oxygen consumption rateThis experiment is performed at 25°C under five salinity levels (10, 20, 30, 40 and 45). Salinity has significant effect on the oxygen consumption rate in the range of 10 to 45 (P<0.001). P. simulus shows lower respiratory rate in midrange salinity (30) and higher respiratory rates in low (10, 20) as well as high (40, 45).When transferred to salinity of 10, the oxygen consumption rate decreases to 0.68 mgO2g-1h-1 about 10-12 h after transfer, and increases to normal value (2.23 mgO2g-1h-1) at salinity of 10. The whole course lasts about 25 h. When transferred to salinity of 45, a decreasing trend lasts about 10-12 h, then the oxygen consumption rate rises to normal value (2.03 mgO2g-1h-1) at salinity of 45 about 20 h after transfer.3. The effects of pressure on the oxygen consumption rateThe oxygen consumption rate is tested under six hydrostatic pressure levels (0, 0.2, 0.4, 0.6, 10, 20 MPa) at 25°C and salinity of 31. The data show that there is significant effect of hydrostatic pressure on oxygen consumption rate measured at 0-20 MPa (P<0.001). Oxygen consumption rate increases slightly with the increase of pressure from 0 to 0.6 MPa, and increases significantly to the maximum at 10 MPa, then decreases at 20 MPa.