Impact of Sublethal Concentrations of Nitrite on Goldfish (Carassius auratus) Microbiomes

Elevated concentrations of nitrite are toxic to fish and can cause a myriad of well documented issues. However, the effects of sublethal concentrations of nitrite on fish health, and specifically, fish tissue microbiomes have not been studied. To test the effects of nitrite exposure, goldfish were exposed to sublethal concentrations of nitrite, 0.0 mM, 0.1 mM, and 1.0 mM, for 2 months. The bacteria in the nose, skin, gills, and water were then extracted and sequenced to identify changes to the microbial composition. The water microbiome was not significantly changed by the added nitrite; however, each of the tissue microbiomes was changed by at least one of the treatments. The skin and gill microbiomes were significantly different between the control and 1.0 mM treatment and the nose microbiome showed significant changes between the control and both the 0.1 mM and 1.0 mM treatments. Thus, sublethal concentrations of nitrite in the environment caused a shift in the fish tissue microbiomes independently of the water microbiome. These changes could lead to an increased chance of infection, disrupt organ systems, and raise the mortality rate of fish. In systems with high nitrite concentrations, like intensive aquaculture setups or polluted areas, the effects of nitrite on the microbiomes could negatively affect fish populations.

Automated summary

Elevated concentrations of nitrite are toxic to fish and can cause a myriad of well-documented issues. This study focused on exploring the effects of sublethal concentrations of nitrite on fish health, specifically on fish tissue microbiomes. The results showed that sublethal concentrations of nitrite caused significant changes in the microbial composition of fish tissue microbiomes, independent of the water microbiome. These changes could have potential negative effects on fish populations, including increased infection risks and disruption of organ systems.