WATER-BALANCE, GROWTH, DEVELOPMENT, AND SURVIVAL OF ARBOREAL FROG EGGS (CHIRIXALUS-EIFFINGERI, RHACOPHORIDAE) - IMPORTANCE OF EGG DISTRIBUTION IN BAMBOO STUMPS

We studied the effects of substrate moisture and flooding on the arbor eal eggs of Chirixalus effingeri and determined the possible causes of egg mortality. Eggs appear highly permeable to water vapor, losing 16 .24% and 38.38% of initial egg mass in 2 h at 90% and 45% relative hum idity, respectively. Eggs that experienced positive water uptake devel oped faster, hatched earlier with larger hatchlings, and had greater h atching success than eggs that experienced negligible or negative wate r uptake. The hatching success of eggs that were submerged in water in bamboo stumps was significantly lower than that of eggs that were inc ubated on the water surface and was significantly correlated with the water Po,. In some bamboo stumps, we observed chironomid and tipulid l arvae preying on submerged eggs. A dilution of water collected from ba mboo stumps did not increase the hatching success of eggs. The water P o-2 Of bamboo stumps in the field was 67.4 +/- 18.8 mmHg, and the degr ee of hypoxia of water in each bamboo stump was correlated with the tu rbidity. Our findings demonstrated that the vertical distribution of C . eiffingeri eggs on walls of bamboo stumps significantly influenced t he growth, development, and survival of embryos. Eggs deposited too fa r from the water may become desiccated, while eggs deposited too close to the water may become submerged and die of hypoxia or predation by insect larvae.