Effects of CO2 , and high temperature on oxygen consumption and growth of striped catfish (Pangasianodon hypophthalmus)

Abstract

Striped catfish (Pangasianodon hypophthalmus) has been farmed commercially in the Mekong river delta of Vietnam. The farming of this species has been exposed to climate change conditions, whereas CO2 and temperature have been forcasted to increase in the coming years. The study aimed to determine the oxygen consumption and growth performance of fish exposed to CO2 and high temperature. The growth experiment was set up with 2 treatments: control treatment (no aerated CO2) and 3% CO2 treatment, each treatment had 2 replicates; temperature was kept constant at 32oC. The second experiment was conducted by measuring oxygen uptake. Fish were acclimated under normocapnia and 3% CO2 condition at 32oC. One fish were collected for driving to exhaustion using the chasing method (Reidy et al., 1995). The fish were left in the intermittent closed respirometry in the same environment with its acclimated environment for 20 hours and standard metabolic rate (SMR), maximum metabolic rate (MMR), routine metabolic rate (RMR) and aerobic scope was measured. Afterwards, a measure of background MO2 was conducted. The same procedure was then conducted in the opposite environment than it was acclimated to. The growth of fish shown that weight gain (WG), daily weight gain (DWG) and specific growth rate (SGR) of fish in 12 weeks exposed 3% CO2 were significant reduced compared to the control treatment (p<0,05). The survival rate (91%) of hypercapnia group and (94%) of normocapnia group was not significant difference. No significant difference was found in SMR, MMR,RMR and scope between groups. SMR of hypercapnic group measured in normocapnia (HN) reached 246.344 ± 21.243 MO2·h-1·kg-1 with a slightly higher compared to other groups. Average RMR was 235-293 MO2·h-1·kg-1 and MMR was near 500 MO2·h-1·kg-1with not significant difference between the groups. There was also not significant difference in scope with values of approximately 240-290 MO2·h-1·kg-1. The results of the study prove that high temperature and 3% CO2 can cause the reduction in growth of Pangasianodon hypophthalmus but it does not cause any consequences for metabolism on this species.