Colonies of Pocillopora damicornis were placed in a sealed aquarium
in the dark. Water velocity was altered and measured in 10 different
experiments. During each experiment, seawater in the aquarium was supersaturated
with oxygen (02 ) and then O2 concentration was measured through time
until the concentration in the aquarium decreased to 0.3 mg O2 1-1 . Resulting
O2 uptake curves were interpreted as a function of water velocity. Rate of O2
uptake fit a hyperbolic equation (d02 /dt = Vm02 /Ks + O2 ) . Maximum uptake
rate (Vm ) varied between 0.12 and 0.27 mg O2 1- 1 min " (mean = 0. 18), and the
half-saturation constant (Ks ) varied between 0.86 and 2.52 mg O2 1-1. Both Vm
and K, did not vary with water velocity, indicating that in these experiments,
water motion had little influence on either diffusive boundary layers near the
coral tissue or the metabolic rate of O2 uptake. Even supersaturated concentrations
of O2 did not completely saturate the uptake capacity of this enzyme
system
