Effects Of Rapid Decompression Research Articles

The effect of rapid decompression on barotrauma and survival rate in swallowtail seaperch (Anthias anthias): Defining protocols for mitigating surfacing mortality

Swallowtail seaperch, Anthias anthias, is a popular fish in the public aquaria industry worldwide, but is subject to barotrauma and high mortality rates if an appropriate decompression profile is not used. Here, we analyze behavioral response to pressure reductions in swallowtail to define protocols for mitigating surfacing mortality. Four different pressure reduction rates were tested (15%, 25%, 35%, and 45%) in several lifting steps from an initial depth of 30 m. Decompression using this procedure was done with 12 and 24 h acclimation duration at each step allowing fish to recover from the pressure reduction. Fish condition was assessed based on swimming behavior, immediately after each new pressure reduction also after each acclimation time. Additionally, fish condition was monitored in a post-decompression trial for 14 days. During decompression, both conditions - initial and final - showed statistically significant differences in the reduction rates tested but showed no differences in acclimation times, and no interaction of the two factors. Neither pressure nor acclimation time affected the condition of the animal in post-decompression trials. Ascension steps near the surface are associated with larger decreases in neutrally buoyant fish compared to deeper decompression steps. Close monitoring of the effect of decompression on A. anthias in the control group, showed that a 29% reduction in pressure could indicate an approximate value of the free vertical range of this species, while swimbladder rupture can occur between 63 and 70% of pressure reduction. The optimal protocol for mitigating surfacing mortality combines two decompression profiles used in this experiment with a total duration of 84 h and comprising 4 lifting steps. The protocol developed to mitigate surfacing mortality was designed for conditions where oceanic cages or containers can be lifted gradually.

Buoyancy adjustment after swimbladder puncture in cod Gadus morhua: An experimental study on the effect of rapid decompression in capture-based aquaculture

Swimbladder puncture occurs frequently during fishing operations employed in capture-based aquaculture (CBA). The function, survival and welfare of cod Gadus morhua following controlled swimbladder puncture in the laboratory was investigated. Anaesthetised cod (n=30) were exposed to reduced pressure using a vacuum chamber and their swimbladders were punctured. The pressure reduction before puncture (~70%), location of the swimbladder puncture sites near the pin bones, intraperitoneal gas evacuation path leading to the anal area and rapid repair mechanism, among other puncture characteristics, were consistent with previous findings. The mortality was low (~6%) during the procedure and did not differ from that of the control group. The experimentally punctured cod were challenged by swimbladder reinflation in a flow-through pressure chamber supplied with a surveillance camera and remote pressure regulation. The punctured fish were capable of swimbladder inflation shortly after puncture and their buoyancy acclimation rates were similar to those of the control fish, with a mean filling rate of 0.22 m h−1. These experiments indicate that swimbladder puncture has minor short-lived and reversible effects on the welfare of the fish.

Ondontecrexis--the effects of rapid decompression on restored teeth.

Abstract The effects of environmental pressure changes, both as a result of exposure to high-altitude flying and diving have long been recognised on bones and the central nervous system. In recent years it has become apparent that pressure changes affect multiple systems in the body with little overt effect. Pain in teeth of workers subject to such environments has been reported, and with the advent of very high pressures used in deep-sea diving the problem has become magnified. A series of experiments was performed on intact and restored teeth to examine whether damage could be induced by rapid and large pressure changes.

THE TADPOLE TAIL AS A MODEL FOR DECOMPRESSION STUDIES

SummaryThe tail of the tadpole of Litoria etoingi (Anura. Hylidae) has been used to visualise directly the growth and reabsorption of gas bubbles in living tissue following decompression. Intravascular bubbles were observed to move along the vascular arcades of the transparent tail fins after rapid decompression from 600 pounds per square inch. Some blood vessels became so distended with gas that they ruptured at intervals along their length mid the bubbles extended into the extravascular tissue. It is therefore suggested that this preparation provides a useful model for studies on the effects of rapid decompression.

Rapid decompression of chimpanzees to a near vacuum.

Physiological effects of rapid decompression of chimpanzees to near vacuum level while breathing pure oxygen