Oxygen uptake rates of Pagothenia borchgrevinki fish affected with x-cell at rest and in strenuous exercise and morphological examination of x-cell affected gills

During the 83-84 season, several Pagothenia borchgrevinki fish were collected which had damaged gills. The gill filaments were white, instead of the usual red colour due to blood perfusion and also appeared to be very swollen. Fish with the same condition were captured in the 85-86 season making up approximately 15% of the captured population. Preliminary work was conducted on the anatomy of these affected gills using scanning and transmission electron microscope. Morphological work found that the affected gill tissue is packed with a foreign cell type, called x-cell. In the 87-88 season, aspects of oxygen uptake under resting and exercise of fish affected with x-cell was examined. Resting fish were placed in a sealed box and the rate of oxygen consumption was determined by monitoring oxygen tension in the water with an oxygen meter and electrode. The fish remained in the respirometer until it showed distinct signs of distress. The oxygen remaining was deemed to be the critical PO2 at which the fish could no longer efficiently extract oxygen from the water. To exercise the fish, they were placed in a closed box tunnel respirometer and exercised with a flow of water for 30 minutes at a high swimming speed. The maximum oxygen consumption (VO2 max) was determined. Fish were then transferred to the closed box respirometer and oxygen consumption over the next one and a half hours was monitored.