17-Beta estradiol and 4-nonylphenol delay smolt development and downstream migration in Atlantic salmon, Salmo salar .
The effect of 17-beta estradiol (E2) and 4-nonylphenol (4-NP) on smoltification and downstream migration of Atlantic salmon was studied in an integrated laboratory and field study. In a stock of hatchery-raised 1-year-old salmon, smoltification progressed from February until late May as judged by in...
| Published in: | Aquatic Toxicology |
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| Main Authors: | , , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
2004
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| Subjects: | |
| Online Access: | https://portal.findresearcher.sdu.dk/da/publications/d4fab650-daf7-11dc-860c-000ea68e967b https://doi.org/10.1016/j.aquatox.2004.03.008 |
| Summary: | The effect of 17-beta estradiol (E2) and 4-nonylphenol (4-NP) on smoltification and downstream migration of Atlantic salmon was studied in an integrated laboratory and field study. In a stock of hatchery-raised 1-year-old salmon, smoltification progressed from February until late May as judged by increased gill Na + , K + -ATPase activity and 24 h sea water (SW)-tolerance. Starting late March, three groups of 150 fish were each given 6 serial injections over 20 days of 2 µg/g body weight E2, 120 µg/g 4-NP dissolved in peanut oil or peanut oil (4 µl/g) as control. After the last injection, all fish were individually tagged (Passive Integrated Transponder tags) and a non-lethal gill biopsy was taken. Two days later (8 April), 100 fish per group were transported to the field site and released into a small stream. Smolt migration was registered by measuring arrival time at a trap downstream of the release site. Serum vitellogenin levels increased several-fold in both male and female E2- and 4-NP-treated fish. Overall, E2- and 4-NP-treatment impaired smolting as judged by elevated condition factor, reduced gill Na + , K + -ATPase activity and alpha-subunit Na + , K + -ATPase mRNA level, reduced muscle water content and increased mortality following 24 h SW-challenge. After release, control fish initiated downstream migration immediately, with 50% of the total number of migrants appearing in the trap within 10 days. E2- and 4-NP-treated fish appeared in the trap with a delay in comparison to controls of 6 and 8 days, respectively. After the smolt run, no fish were registered by electro-fishing upstream of the trap. The total number of fish reaching the trap and thus post-release survival was in the order control (81%), E2 (53%), 4-NP (12%). Representatives from all treatment groups held under simulated natural conditions in the laboratory survived 100% through the migration period, suggesting that a combination of behavioural and in-stream factors (predation by herons) may contribute to the differential mortality. The ... |
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