Mechanisms responsive to hypercapnia (elevated CO2 concentrations) and shaping branchial energy turnover were investigated in isolated perfused gills of two Antarctic Notothenioids (Gobionotothen gibberifrons, Notothenia coriiceps). Branchial oxygen consumption was measured under normo- versus hypercapnic conditions (10,000 ppm CO2) at high extracellular pH values. The fractional costs of ion regulation, protein and RNA synthesis in the energy budgets were determined using specific inhibitors. Overall gill energy turnover was maintained under pH compensated hypercapnia in both Antarctic species as well as in a temperate zoarcid (Zoarces viviparus). However, fractional energy consumption by the examined processes rose drastically in G. gibberifrons (100-180%), and to a lesser extent in N. coriiceps gills (7-56%). In conclusion, high CO2 concentrations under conditions of compensated acidosis induce cost increments in epithelial processes, however, at maintained overall rates of branchial energy turnover.

Specimens of Gobionotothen were collected during an Antarctic summer expedition with RV POLARSTERN in 2006/07 (ANT-XXIII/8) from bottom trawls at depths of 60-490 m at the Antarctic Peninsula near Elephant and Joinville Island. Notothenia coriiceps were caught with fish traps at Jubany station (King-George-Island). Commom eelpout (Zoarces viviparus) were caught with bottom traps in the German bight near Helgoland in April 2004 and April 2005.

Supplement to: Deigweiher, Katrin; Hirse, Timo; Bock, Christian; Lucassen, Magnus; Pörtner, Hans-Otto (2010): Hypercapnia induced shifts in gill energy budgets of Antarctic notothenioids. Journal of Comparative Physiology B-Biochemical Systemic and Environmentalphysiology, 180(3), 347-359