Abstract

In the north of Chile, several projects propose to promote the diversification of national aquaculture with native fish species. However, one of the expected impacts of climate change on the Chilean coasts is an increase in the intensity and frequency of hypoxia events. Therefore, it can become one of the main problems for fish aquaculture in farming facilities. Two species of Chilean diversification programs are Seriola lalandi and Seriolella violacea, which have different habitats and may have different oxygen requirements. Thus, this work aimed to evaluate the variations in oxygen consumption rates in 10 month-old juveniles of both fish species and to determine the presence of tolerant and non-tolerant individuals at low dissolved oxygen (DO) availability. A simulation of an acute hypoxia event by loss-of-equilibrium (LOEhyp) experiments allowed us to classify tolerant and non-tolerant fish. Then, individual oxygen consumption rates were measured, and the resting metabolic rate (RMR) and the maximum metabolic rate (MMR) for hypoxia-tolerant and non-tolerant juveniles were obtained. The results reveal that S. lalandi juveniles have a higher oxygen demand than S. violacea, the first presenting a significantly higher metabolic rate and locomotor activity. Furthermore, the blood parameters suggest that triglyceride metabolism could be used as alternative energy sources by S. violacea during hypoxic-environments. The juveniles classified as tolerant from both species have a lower RMR than non-tolerant fish, which is associated with reduction in their locomotor activity evidenced by decreasing tail beat frequency. Furthermore, the hypoxia-tolerant juveniles also reached a significantly higher size than non-tolerant fish. This work provides valuable results for the future S. lalandi and S. violacea industries, considering the effects of low OD in the farms. Likewise, the first evidence of the hypoxia adaptive mechanism of native fish are presented, providing scientific support for their aquaculture in Chile.