ABSTRACT
This chapter investigates developmental changes in oxygen consumption rates of periophthalmus modestus (P. modestus) eggs in air and water, effects of aerial hypoxia on oxygen consumption rate, and survival of the eggs and newly hatched larvae in hypoxic water. Eggs of P. modestus were collected in June and July, 2003, at an estuarine mudflat along a tributary of Rokkaku River, Saga, Japan. Oxygen levels of the gas samples obtained from P. modestus burrows generally ranged from 48 to 93% of outside air level, although gaseous PO2 were often considerably lower when collected from burrows with guarding male displaying courtship behavior. Heart rate decreased significantly only in 10% air in eggs of both stages. Normally transparent embryonic body became opaque in those individuals that developed slowed heart rate. Oxygen consumption rate of the eggs significantly decreased in the lowest hypoxic condition.
