The effects of temperature and oxygen partial pressure on the rate of oxygen consumption of the high-shore rock pool copepod Tigriopus brevicornis

Inhabitants of littoral rock pools such as the copepod Tigriopus brevicorni s are subjected to highly variable physico-chemical conditions. The effect of temperature and P-O2 On the rate of oxygen consumption of T. brevicornis from a Scottish population was studied. As expected, V-O2 increased with i ncreasing temperature over the range 5-30 degrees C. However, at 0 and 35 d egrees C the rates of oxygen consumption were significantly lower than pred icted. This was reflected in the very different values for Q(10) obtained o ver the temperature range 0-5 degrees C (due to T. brevicornis entering a d ormant state at 0 degrees C) and 30-35 degrees C (due to high mortality at 35 degrees C), compared with the mean Q(10) of 2.9 for the temperature rang e 5-30 degrees C. Spectrophotometric studies of the body fluids of T. brevi cornis failed to detect the presence of a respiratory pigment. Nevertheless , T. brevicornis was able to maintain its rates of oxygen consumption indep endent of P-O2 under conditions of declining oxygen tension. However, the a bility of T. brevicornis to maintain respiratory independence under hypoxia was affected by temperature since the P-c was higher at 30 degrees C than at lower temperatures. T. brevicornis appears to be able to withstand expos ure to low temperature and to severe hypoxia by entering a quiescent or dor mant state during which its metabolic rate is significantly reduced. (C) 19 99 Elsevier Science Inc. All rights reserved.