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| Titel |
Water quality limits for Atlantic salmon (Salmo salar L.) exposed to short term reductions in pH and increased aluminum simulating episodes |
| VerfasserIn |
F. Kroglund, B. O. Rosseland, H.-C. Teien, B. Salbu, T. Kristensen, B. Finstad |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 12, no. 2 ; Nr. 12, no. 2 (2008-03-05), S.491-507 |
| Datensatznummer |
250010571
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| Publikation (Nr.) |
 copernicus.org/hess-12-491-2008.pdf |
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| Zusammenfassung |
| Acidification has caused the loss or reduction of numerous Atlantic salmon
(Salmo salar L.) populations on both sides of the North Atlantic. Acid deposition
peaked in the 1980's and resulted in both chronically and episodically
acidified rivers. At present, water quality is improving in all affected
rivers due to reduced acid deposition. However, spring snow melt, heavy
rainfall and sea salt episodes can still cause short term drops in pH and
elevated concentrations of bioavailable aluminum. Technical malfunction in
lime dozers will cause short termed episodic spates in the limed rivers. The
current situation has prompted a need for dose-response relationships based
on short term exposures of Atlantic salmon to assess the potential
population effects of episodic acidification. Water quality guidelines for
salmon have been lacking, despite a large number of experiments, all
demonstrating dose-response relationships between water chemistry and fish
health. We have summarized results from 347 short-term (<14 days)
exposures of salmon parr and smolt performed between 1990 and 2003 in
Norway. The experiments have been performed as bioassays, where fish have
been exposed in tanks fed river water, in tanks where the river water
quality has been manipulated (added H+ and Al) and as Carlin-tagged
smolt releases after preexposure to moderately acidic waters. The results
from the various bioassays are compared to water quality limits proposed on
basis of the relationship between water quality and population status/health
in Norwegian rivers. The focus of this article is placed on
chemical-biological interactions that can be drawn across experiments and
exposure protocols. We propose dose-response relationships for acid
neutralizing capacity (ANC), pH, cationic Al and gill accumulated Al, versus
mortality in freshwater, effects on hypo-osmoregulatory capacity in seawater
challenge tests and on smolt to adult survival in release experiments. The
"no effect" dose depends on the life history stage tested and on the
sensitivity of the biomarkers. Parr are more tolerant than smolt.
Concentrations of Al that have no significant impact on freshwater life
history stages can still have major population effects if they occur prior
to smolt migration. While smolt can survive in freshwater for a prolonged
period of time (>10 days) at an Al dose resulting in a gill Al
concentration of up to 300 µg Alg−1 dw, a 3 day exposure resulting
in a gill Al accumulation in the range of 25 to 60 µg Alg−1 dw
reduces smolt to adult survival in a dose related manner by 20 to 50%.
For smolt to adult survival, the biological significant response is delayed
relative to the dose and occurs first after the fish enters the marine
environment. In addition to exposure intensity and timing, exposure duration
is important for the setting of critical limits. |
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