1. The effects of dissolved oxygen level on the metabolic interaction between digestion and locomotion in juvenile southern catfish (Silurus meridionalis Chen)
- Author
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Zhang, Wei, Cao, Zhen-Dong, Peng, Jiang-Lan, Chen, Bo-Jian, and Fu, Shi-Jian
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DISSOLVED oxygen in water , *FISH metabolism , *FISH locomotion , *CATFISHES , *FISH feeds ,FISH digestive organs - Abstract
Abstract: To investigate the effect of dissolved oxygen level ([O2]) on maintenance metabolism, feeding metabolism, aerobic swimming performance and their metabolic interaction in juvenile southern catfish (Silurus meridionalis Chen), we measured the following: (1) the resting oxygen consumption rate (MO2rest) over a range of water [O2] and from this we calculated the critical oxygen tension (P crit) of fasting fish; (2) the postprandial MO2 response (10% body mass meal size) at water [O2] of 1, 2, 4 and 8mgO2 L−1; and (3) the swimming performance of fasting and digesting fish at water [O2] of 1, 2, 4 and 8mgO2 L−1 at 25°C. The MO2rest remained constant over a broad range of water [O2] but then dropped markedly upon reaching the P crit (16.4% saturation). Hypoxic groups presented lower peak postprandial MO2 (MO2peak) (1mgO2 L−1 group), larger energy expenditure and longer digestive process (both 1 and 2mgO2 L−1) than those of normoxic groups. Both critical swimming speed (U crit) and the active metabolic rate (MO2active) of fasting fish remained unchanged over a decrease in water [O2] from 8 to 4mgO2 L−1 and then decreased significantly with further decreases in water [O2]. These parameters in fed fish showed a pronounced decrease as water [O2] decreased from 8 to 1mgO2 L−1. Feeding caused a significantly lower U crit in the 2mgO2 L−1 water [O2] group, a significantly higher MO2active in both the 2 and 8mgL−1 water [O2] groups and a significantly higher metabolic scope (MO2active − MO2rest) in both the 2 and 4mgO2 L−1 water [O2] groups compared to fasting fish. The MO2 increased greatly with swimming speed in the higher water [O2] groups, whereas it leveled off as swimming speeds approached the U crit in the lower water [O2] groups. Within all water [O2] groups, feeding caused a higher MO2 compared to fasting fish when fish swam at the same speeds, except in the 1mgO2 L−1 group. This finding showed that the critical water [O2] for maintenance of metabolism, digestion, swimming and postprandial swimming increased sequentially due to the increasing O2 demand, which challenges respiratory capacity. With the administration of the medium-sized meal that was used in this study, the metabolic mode of juvenile southern catfish changed from an additive mode during normoxia to a digestion-priority mode under moderate hypoxia and to locomotion-priority mode under hypoxia. [Copyright &y& Elsevier]
- Published
- 2010
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