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Biochemical and physiological effects in farmed Baltic salmon
fed lipids containing xenobiotics extracted from Baltic herring
Tommy Andersson1,
Bengt-Erik Bengtsson2*,
Per-Anders Bergqvist3, Torleif
Eriksson4, Åke Larsson2*
& Leif Norrgren5,6
1Department of Zoophysiology,
University of Gothenburg, Medicinaregatan 18 S-413 90 Göteborg,Sweden;
2Swedish Environmental Protection Agency, Aquatic Toxicology
Section,
S-611 82 Nyköping, Sweden;
3lnstitute of Environmental
Chemistry, University of Umeå, S-901 87 Umeå,
Sweden;
4Department of Aquaculture,
Swedish University of Agriculture Sciences,
S-901 83 Umeå, Sweden;
5Department of Pathology,
Faculty of Veterinary Sciences, Swedish University of Agricultural
Science, S-750 07 Uppsala, Sweden;
6Swedish Environmental Research
Institute, Box 21061, S-100 31 Stockholm;
*Present address: Laboratory of Aquatic Ecotoxicology Institute
of Applied Environmental Research, University of Stockholm,
Studsvik, S-611 82 Nyköping, Sweden
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Abstract
During a 2-year experimental period female Baltic salmon
(Salmo salar) were fed pellets impregnated with oil extracted
from Baltic herring (Clupea harengus). This extract contained
lipid-soluble xenobiotics present it Baltic herring, which constitute
a major part of the natural diet of Baltic salmon. The fish were
examined at the time of ovulation in November each year. After 2
years of feeding, the load of polychlorinated dibenzo-para-dioxins
and furans in the exposed group was about twice that in the control
group, but stilt low compared with concentrations in feral Baltic
salmon. In spite of the relatively low exposure level, several vital
biochemical functions were disturbed in the treated fish. Organic
skeletal variables were affected indicating that the bone metabolism
had been altered. Furthermore, the activities of enzymes involved
in steroid biosynthesis were affected, which could lead to disturbances
in reproductive functions. Splenocytes from exposed fish sampled
in November 1990 showed a reduced mitogenic response, indicating
that their immune system was suppressed. Feeding the salmon with
pollutant-impregnated pellets also resulted in an induction of the
hepatic ethoxyresorufin-O-deethylase (EROD) activity after only
6 weeks of exposure. Likewise, morphological abnormalities, i.e.
hypertrophic hepatocytes and various stages of hepatic degeneration,
were already apparent after 6 weeks of exposure. However, no EROD
induction or morphological responses were recorded at the second
and third sampling event, i.e. after one and 2 years of exposure,
respectively. This could indicate that some physiological functions
may adapt to a restricted xenobiotic load.
Keywords: aquatic pollutants, fish, salmon, biochemical and
physiological effects, dioxins, furans
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