Xenobiotic Impact on Arctic Charr: Nutritional Modulation and Physiological Consequences
The Problem
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Arctic
charr, Salvelinus alpinus. |
The Arctic charr (Salvelinus alpinus) in the northern most latitudes
migrate to the ocean in the spring to feed and grow. This results in accumulation
of polychlorinated biphenyls (PCB) in their visceral fat. During the winter,
the charr reside in freshwater lakes and do not feed. They do mobilize
lipids from adipose tissue for energy, which results in a re-distribution
of PCBs to organs such as brain, spleen and heart. Results of this project
will help to describe the effects of PCBs on physiological processes of
charr and other salmonids. This project is funded under reimbursable agreement
number 0PP-9908890 with the National Science Foundation.
Objectives
The long term objective of the work is to investigate the impact of persistent
organic pollutants (POP) on critical tissue function and performance of
anadromous Arctic charr. We will test two hypotheses: (1) the tissue re-distribution of PCB and their sublethal impact is tightly linked
to metabolic status of the animal and (2) the tissue redistribution of
PCB associated with fasting will decrease the overall performance charracteristics
of the animals. Experiments will be performed in Norway, at the Kårvik
Research Station, Tromsø and at a hatchery in Talvik, northern Norway.
Methodology
Hatchery-reared Arctic charr will be contaminated with one of four concentrations (0, 1, 10, 100 mg/kg fish weight) of Aroclor 1254 by force-feeding it in a capsule. After contamination, some fish will be fed and others will be starved to simulate the nutritional status of fish in the wild. After six months, physiological responses of the fish will be tested. Tests will include: disease resistance and innate immune response, stress response, saltwater adaptation, and metabolic responses. These physiological responses will be measured by looking at the whole animal response (e.g., survival), biochemical response (e.g., hormone or cytokine production) and molecular response (i.e., gene transcription).
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Talvic
Hatchery in northern Norway. |
Highlights and Key Findings
In 2000, we conducted experiments with hatchery charr that had been treated
with 0, 1, 10 or 100 mg of Aroclor 1254 per kg body weight. All of these
groups were fasted, but other fish in the 0 and 100 treatments were fed
from the time of exposure until just before our experiments. The exposures
were completed in Feb 2000. We conducted the following experiments: (1)
disease challenge: 40 marked fish from each group were exposed to other
fish that were infected with the fish pathogen Aeromonas salmonicida,
the causative agent of furunculosus. We observed a dose-dependent increase
in mortality of the fasted fish, with mortalities of 32, 42, 52, and 55%
in the fish treated with increasing doses. We are in the process of assaying
fish from each treatment that were not exposed to the pathogen for plasma,
muscus and nare lysozyme, and plasma lectin, (2) handling stress after
which fish were sampled at 1, 3, 6, 12 & 23 hours. We found a dose-dependent
decrease in maximum plasma cortisol responses (Jørgensen et al., 2002)
(3) Plasma and tissues from treatment and control fish that were not stressed
or exposed to pathogen were collected and will be assayed for a number
of physiological variables. In 2001, fish were treated with the same doses
of Aroclor 1254 and we are assaying these to determine the mechanisms
by which the contaminant reduced disease resistance and dampened the stress
response.
Where Are We Headed In 2003
The National Science Foundation, the funding agency, has granted a no-cost extension for this project to December 31, 2003. During this year, we will complete three pending publications and prepare a proposal to continue this project. In the continuation project, we hope to collect maturing fish from two sites--one in which fish are heavily contaminated with PCBs and another where they are not. The fish will be taken to the Kårvik Research Station where they will be spawned and the progeny reared to determine if contamination of the parents has effects on the offspring.
Project Contact
Alec G. Maule
U.S. Geological Survey
Western Fisheries Research Center
Columbia River Research Laboratory
5501-A Cook-Underwood Rd.
Cook, WA 98605-9717
Email: alec_maule@usgs.gov
Phone: 509-538-2299 x 239
Fax: 509-538-2843
Publications
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