Causes and consequences of gill remodelling in the goldfish, Carassius auratus

Abstract

Goldfish are able to drastically change their gill morphology by forming an interlamellar cell mass (ILCM) when acclimated to temperatures below 15 ° C. This morphological change is reversed when the fish is exposed to hypoxia or an increase in temperature. The main goal of this thesis was to investigate how the presence of the ILCM affects the transfer and sensing of respiratory gases as well as to identify the cues that trigger gill remodelling. Using an extracorporeal blood shunt to measure blood gases, I show that the presence of the ILCM does not impede O2 uptake under normoxic or hypoxic conditions but presents an additional diffusion limitation to CO 2 excretion owing to chemical equilibrium constraints. Hypoxemia induced by carbon monoxide or phenylhydrazine elicited a decrease in the ILCM in cold (70 C) acclimated goldfish while exposure to hyperoxia partially prevented the reduction of the ILCM during a temperature increase.