Acute hydrogen sulfide exposure in post-smolt Atlantic salmon ( Salmo salar ): Critical levels and recovery
Despite the importance of Atlantic salmon in marine aquaculture production systems, remarkably little is known about the effects of hydrogen sulfide (H 2 S) on the physiology of the species. In recent years, mass mortalities of Atlantic salmon have been reported in recirculating aquaculture systems...
| Published in: | Aquaculture |
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| Main Authors: | , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
2023
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| Subjects: | |
| Online Access: | https://orbit.dtu.dk/en/publications/dc8cfd59-726a-41aa-b332-ee852bc8150b https://doi.org/10.1016/j.aquaculture.2023.739405 https://backend.orbit.dtu.dk/ws/files/312224743/1_s2.0_S0044848623001795_main.pdf |
| Summary: | Despite the importance of Atlantic salmon in marine aquaculture production systems, remarkably little is known about the effects of hydrogen sulfide (H 2 S) on the physiology of the species. In recent years, mass mortalities of Atlantic salmon have been reported in recirculating aquaculture systems (RAS) due to acute H 2 S exposure. This highlights the importance of obtaining a better understanding of tolerance thresholds and metabolic responses to this toxic gas. The toxicity of H 2 S is exerted at the level of the mitochondria, where impairment of the enzyme cytochrome c oxidase inhibits cellular respiration. Because H 2 S depresses oxygen uptake (MO 2 ), intermittent flow-through respirometry, a common method for assessing the metabolic response to various stressors in fishes, is a suitable method to determine concentration thresholds for when H 2 S affects the metabolism of Atlantic salmon. During exposure trials, 3 size groups (range ⁓100-500 g) of fish were acclimated to control conditions to obtain baseline measurements, whereafter they were exposed to progressively increasing H 2 S concentrations (0.53 ± 0.14 μM h −1 ) until MO 2 decreased below the standard metabolic rate or loss of equilibrium occurred, which we considered to be the critical H2S concentration (H 2 S crit ). Fish were then allowed to recover in H2S free water to determine the excess oxygen consumption (EOC) following H2S exposure. The results show that Atlantic salmon have a lower tolerance to H 2 S than previously estimated, with a mean H 2 S crit of 1.78 ± 0.39 μM H 2 S, which was independent of size. During recovery, the estimated EOC greatly exceeded the accumulated oxygen deficit (DO 2 ) in all groups, and the small salmon had a significantly larger EOC. While the magnitude of the EOC was greater for small salmon, it did not differ in duration (recovery time) among the different sizes of fish. The larger EOC showed that H 2 S exposure had a greater effect on the recovery phase of the small salmon, and exposure to H 2 S may leave ... |
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