I 



A. V. Nebeker 

 D. G. Stevens 

 J. R. Brett 



Effects of Gas 



Supersaturated 



Water on Freshwater Aquatic 



Invertebrates 



ABSTRACT 



Tests with the stoneflies Acroneuria californica, Acroneuria 

 pacifica, and Pteronarcys californica; Daphnia magna; crayfish 

 (Pacifastacus leniusculus); and young steelhead trout (Salmo 

 gairdneri) were conducted to determine the sensitivity of fresh- 

 water insects, Crustacea, and fish to gas supersaturated water. 

 Stoneflies and crayfish were tolerant of supersaturation levels 

 (125%) that killed trout; however, survival was similar in Daphnia 

 and trout. Crayfish died at 150% and 140%; some deaths and 

 sublethal signs occurred at 130%. Stoneflies were immobilized 

 at 135% and exhibited buoyancy problems at 125%, but were 

 unaffected at 115%. Daphnia were killed at 120% and exhibited 

 partial mortality at 115%; air in the gut caused food blockage 

 and subsequent starvation. Bubbles were observed in body fluid 

 and tissues, and general body distention occurred before death 

 in Daphnia, crayfish and stoneflies. The open circulatory system 

 of invertebrates, relatively simple compared to fish, appeared 

 to be the main reason for the greater tolerance of insects and 

 Crustacea to gas bubble disease. They do not have the complex 

 capillary blood vessel system of fish which is rapidly blocked by 

 bubbles, or emboli, that form in the blood. 



and fish: Daphnia magna; western crayfish, 

 Pacifastacus leniusculus; three stoneflies, Acro- 

 neuria californica, Acroneuria pacifica, and Ptero- 

 narcys californica; and juvenile steelhead, Salmo 

 gairdneri. 



MATERIALS AND METHODS 



Physical Conditions 



Five 6000-C fiberglass tanks, 60 cm deep, were 

 used for maintaining four different levels of super- 

 saturated water and one saturated control (Fig. 1). 

 A supersaturation generator system (Fig. 2) was 

 used to control the gas level in each tank. Test 

 water was obtained from two wells located about 

 30 m from the Willamette River. Water was chilled, 

 aerated to saturation, heated to a given tempera- 

 ture with immersion heaters, pumped under 



The effects of supersaturated water on fish, the 

 so-called gas bubble disease (GBD), have been 

 familiar to aquarium and hatchery workers for many 

 years (Marsh and Gorham, 1905; Embody, 1934; 

 Rucker and Hodgeboom, 1953). Supersaturated 

 water (up to 150% total dissolved gas) created by 

 dams on the Columbia River, and its effect on fish, 

 have recently been described by Westgard (1964), 

 Pauley and Nakatani (1967), Ebel (1969), and others. 

 Three recent literature reviews (Rucker, 1972; Weit- 

 kamp and Katz, 1973; and Bouck, 1974) adequately 

 summarize previous work on gas bubble disease 

 and supersaturated water problems. Laboratory 

 studies have been conducted recently by Blahm et 

 al. (1973) and Bouck et al. (1973) to determine 

 comparative sensitivity of various fish species to 

 supersaturated water, but little work has been 

 completed with fish-food organisms, especially 

 freshwater invetebrates. 



This study was conducted to determine the 

 effects of various levels of supersaturated water on 

 the following freshwater aquatic insects, Crustacea, 



FIG. 1 View of interior of test tank showing open tank and net 

 cages for isolating crayfish. 



Nebeker, Stevens, and Brett: U.S. Environmental Protection 

 Agency, Western Fish Toxicology Station, Corvallis, Oregon. 



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