COMPOSITION OF THE SWIMBLADDER GAS IN DEEP SEA FISHES

Open Access
Publisher Website
Google Scholar
Abstract
1. The composition of the swimbladder gas has been determined in 26 species (260 specimens) of marine deep-sea fishes taken at known depths between 200 and 950 meters. 2. The partial pressure of nitrogen in the bladder steadily increases with depth until it reaches some 5-15 atmospheres at a depth of 900 meters, revealing that not only oxygen but also nitrogen is transported into the swimbladder against a considerable gradient. This corroborates the findings of Hüfner (1892) that the whitefish (Coregonus) is able to secrete pure nitrogen against a hydrostatic pressure of 6-8 atmospheres. 3. The data, together with previous observations from shallower depths, show that the nitrogen tension at all depths may be expressed by (1) a diffusion term of 0.8 atmosphere, plus (2) a secretion term which, although different for different species of fish, is in each species a constant percentage of the total secreted gas pressure. Among our fish the secretion term ranges from about 2% to 15% nitrogen. In the whitefish it is apparently 100%. In a steady-state situation the percentage nitrogen actually secreted into the swimbladder is probably lower than the nitrogen percentage indicated by the secretion term because oxygen is more easily lost by diffusion through animal tissue than is nitrogen.