Notes: Oxygen Consumption by Larval Japanese Medaka with Inflated or Uninflated Swim Bladders

Abstract

Inflation and regulation of swim bladder volume enables fish to maintain position within the water column with minimal energy cost. Larvae whose swim bladders fail to inflate must move to stay suspended and would be expected to use additional energy to maintain position. As a relative measure of extra effort expended by fish with uninflated swim bladders, oxygen consumption rates at 26°C were compared for larval Japanese medaka Orvzias latipes with inflated and uninflated swim bladders. During the first 24 h after hatching, oxygen consumption rates were significantly higher for larvae with uninflated swim bladders (1.75 ± 0.13 μg O2·h−1·larva−1) than for those with inflated swim bladders (0.92 ± 0.05 μg O2·h−1·larva−1); after 96 h, oxygen consumption rates had decreased for all larvae to about 0.6 μg O2·h−1·larva−1. For larvae held in sealed containers for 72 h without access to free surface air, the volume of air-saturated water required to maintain an adequate concentration of dissolved oxygen (>6 mg/L) was greater when swim bladders were uninflated (55 mL/ larva) than when swim bladders were inflated (36 mL/ larva).