Influence of oxygen regimes of water on the physiological state of fish (review)

Abstract

Breeding of sturgeon fish species in recirculating water supply systems is one of the most promising areas in modern aquaculture. With proper operation of recirculation systems and compliance with the requirements for fish breeding, it becomes possible to reduce anthropogenic pressure on fish populations living in natural reservoirs, as well as provide the country’s population with highquality fish products. The use of recirculating water supply systems for sturgeon breeding has many advantages, such as: a smaller number of compound feeds, automation of the process, saving water used and building a small plant in places near settlements, etc. The only exceptions are the two main disadvantages that cause stress in fish — a low level of oxygen dissolved in water and an increased stocking density of bred individuals. Due to the fact that the issue of stocking density regulation is quite well studied, the issue of oxygen effects on physiological changes in fish is very relevant. The aim of the work was to analyze domestic and foreign literature, which describes the effect of different levels of saturation of the aquatic environment with dissolved oxygen on the viability of sturgeons bred in recirculating water supply systems. This review reflects the existing data on the norms of consumption by sturgeons of oxygen dissolved in the aquatic environment, critical and threshold concentrations that affect the body of aquatic organisms and cause them physiological manifestations with concomitant pathologies. This review also summarizes information describing the current requirements for maintaining the oxygen regime when breeding sturgeons in recirculating water supply installations, the effect of different concentrations of oxygen dissolved in water on the pathophysiological state of aquatic organisms, depending on their weight and age. The article deals with the issue of physiological abnormalities that manifest themselves under hyper- and hypoxic exposure. The consequences of hypoxic exposure with increased planting density in containers intended for keeping aquatic organisms are described.