Histopathoiogy and the Pathogenesis of Embolism (Gas Bubble Disease) in Rainbow Trout (Salmo gairdneri)

Abstract

Rainbow trout (Salmo gairdneri) affected with gas bubble disease (GBD) were examined histologically to determine the pathogenesis of the early stages of gas emboli formation. Lesions preserved by a rapid fixation method were located in tissues associated with acid-secreting glands or with high metabolic requirements. Following the development of small gas emboli formed in the retinal chorio-capillaries, a progressive development of unilateral exophthalmia was detected. A lesion found in every treated moribund fish but never in controls was gas displacement of the blood from the afferent arteriole within the gill filaments. The exposure of fish to well water containing graded levels of atmospheric gases from 114 to 118% nitrogen and 103 to 110% oxygen saturation resulted in high mortality. However, fish held in nitrogen varying between 103 and 117% and oxygen from 50 to 94% saturation experienced insignificant mortality. We suggest that hatchery oxygen levels should be maintained below 100% if nitrogen supersaturation is present to reduce mortality from GBD.

A Simple Apparatus for Maintaining Gas‐Supersaturated Seawater in the Laboratory for Experimental Purposes

“…Variations in operating conditions were within acceptable levels and consistent with those reported in the literature (Knittel et al 1980;Machado et al 1987;Herman 1989, 1991;Edsall and Smith 1991;Smith 1991, 1993;Counihan et al 1998). The largest variation in TDG observed in this apparatus Variance decreased, however, in chronic and oxygen enrichment experiments to 5.6 mm Hg or less and was lower than reported variances in the literature.…”

“…This consistency in operation is important and has not always been achieved. For example, some researchers applied treatments that were dependent on mixing warm and cold water from lakes (Machado et al 1987;Krise and Smith 1993;Mesa and Warren 1997) or pumping water from depth (Beyer et al 1976;Bouck 1980). These types of control systems often varied from month to month, yielding highly variable saturation, water temperature, and gas partial pressure treatments.…”

“…To create a gas-supersaturated environment, researchers have used a variety of techniques, including (1) mixing warm and cold water (Machado et al 1987;Krise and Smith 1993;Mesa and Warren 1997), (2) using pressurized water from depth (Beyer et al 1976;Bouck 1980), (3) utilizing air-injected pressure systems (Rucker and Kangas 1974;Gray et al 1982Gray et al , 1985Shrimpton et al 1990;Caldwell and Hinshaw 1994;Schisler et al 1999), or (4) using a combination of heating and air injection (Chamberlain et al 1980). The methods employed generally have created a single saturation level and have not allowed for control of water temperature.…”

Communications: Histopathology of Gas Bubble Disease in Juvenile Rainbow Trout

“…Detailed reports of the histopathology of GBD are limited (Pauley and Nakatani 1967;Machado et al 1987). The purpose of the present study was to describe histopathological changes in rainbow trout (Salmo gairdncri) having GBD.…”

Gas Bubble Disease Monitoring and Research of Juvenile Salmonids : Annual Report 1996.

“…Unfortunately, these accounts often lack explicit detail, do not attempt to quantify the severity of signs, or are at a histological level. Although the histological descriptions of GBT (Machado et al 1987;Smith 1988;Machado et al 1989) are quite detailed, they are of little practical use to a monitoring program where the emphasis is on a rapid, non-lethal assessment of GBT. Despite the large amount of research on GBT in fishes, which has primarily examined acute mortality, the development of methods to provide a rapid, quantitative description of the signs of GBT is still lacking.…”