EFFECT OF COPPER IONS ON GROWTH AND BACTERIAL ABUNDANCE IN THE INTESTINAL TRACT OF RAINBOW TROUT (ONCORHYNCHUS MYKISS) LARVAE

Abstract

Abstract. The effect of copper ions in water on the growth of rainbow trout (Oncorhynchus mykiss) larvae and abundance of bacteria in the intestinal tract was studied. Exposure to copper reduced the growth of fish larvae and the abundance of bacteria in the intestinal tract. Populations of aerobic total heterotrophic bacteria present in the intestinal tract of rainbow trout larvae, estimated using the dilution plate technique, decreased approximately from log 5.30 CFU/g in control larvae to log 2.39 CFU/g after the exposure to 0.03 mg/l of copper. Proteolytic bacteria proved to be the most sensitive to copper. The abundance of these bacteria in the intestinal tract of larvae decreased significantly after the exposure to the lowest tested copper concentration. In these experiments the cultivable bacterial densities increased after the exposure to 0.25 mg/l of copper, possibly as a result of the release of organic carbon from the poisoned copper-sensitive organisms.

Effects of copper microparticles on the growth and survival of juvenile rainbow trout (Oncorhynchus mykiss Wal.)

“…The growth rate of rainbow trout larvae reacts sensitively to the chronic toxicity of copper ions, i.e. by increasing the content of copper ions in water, the growth of rainbow trout larvae decreases (Mickėnienė et al, 2007). Marr et al (1996) state that exposure to copper concentrations in water of 4.6 ng l -1 resulted in reduced growth of juvenile rainbow trout in the experimental group of about 4.5% compared to the control group, with individuals not recovering and achieving a growth rate of individuals from control groups during the exposure period, i.e.…”