Oxygen uptake of developing eggs of Cancer pagurus (Crustacea : Decapoda :Cancridae) and consequent behaviour of the ovigerous females

This study investigated factors affecting the metabolic rate of Cancer pagu rus eggs. The oxygen uptake of portions of the egg mass and recently hatche d zoeae was measured. Oxygen uptake of the eggs of an individual animal was found to vary widely, with measured mean values under normoxic conditions ranging from 38 to 250 mu moles O-2 kg(-1) min(-1) Mean values for the oxyg en uptake of zoeae ranged from 958 to 1168 mu moles O-2 kg(-1)min(-1) Mean rates of oxygen uptake of the eggs generally increased with increasing seas onal temperature and advancing developmental stage. Rates of oxygen uptake were maintained over a wide range of ambient oxygen partial pressures. As o xygen partial pressure in the seawater surrounding the eggs fell from a cri tical value (P-c) of between 60 and 90 mm Hg, the oxygen uptake of the eggs also declined. Mean values for ambient oxygen partial pressures within the egg mass in vivo ranged from 34 to 98 mm Hg. Adult female C. pagurus appea r to be able to detect conditions within the egg mass and adjust their egg ventilation behaviour accordingly. Active egg mass ventilation by the adult increased as the eggs became more developed and their oxygen demands incre ased.