Difference between revisions of "PCB and heavy metals in beached sperm whales"
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<u>'''Main results'''</u> | <u>'''Main results'''</u> | ||
| − | High concentrations of [[cadmium toxicity|cadmium]] (up to 300 µg/g dry weight in the kidney), [[mercury toxicity| total mercury]] (up to 130 µg/g dry weight in the liver) and [[PCB|PCB's]] (up to 5 µg/g in [[blubber]]) were retrieved in these sperm whales. [[Methylmercury]] averaged 4% of total mercury concentrations in the liver and 90% in the muscles. | + | High concentrations of [[cadmium toxicity|cadmium]] (up to 300 µg/g dry weight in the kidney), [[mercury toxicity| total mercury]] (up to 130 µg/g dry weight in the liver) and [[PCB|PCB's]] (up to 5 µg/g in [[blubber]]) were retrieved in these sperm whales. [[Methylmercury]] averaged 4% of total mercury concentrations in the liver and 90% in the muscles. Less than 66% of the [[Cadmium toxicity|Cd]] found in the livers and kidney's were bound to [[metallothionein|metallothioneins]]; these are proteins which animals produce to counteract the harmful effects of metals. Therefore the remaining 33% might not have been detoxified. |
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[[Organochlorine]] concentrations in the [[blubber]] were found to be low compared to other species. Since similar levels have been shown to have caused reproductive and [[immune-deficiency]] problems in marine mammals, this doesn't necessary imply lack of effect. | [[Organochlorine]] concentrations in the [[blubber]] were found to be low compared to other species. Since similar levels have been shown to have caused reproductive and [[immune-deficiency]] problems in marine mammals, this doesn't necessary imply lack of effect. | ||
| − | + | Although other studies have shown that stable [[pollutants]] (like PCB and mercury) tend to accumulate in marine mammals with increasing age, this study didn't find higher concentrations of any contaminant in the oldest animal (the one that died of old age before stranding). Since he was estimated to be at least 60, this means that he was born in the pre-organochlorine period and therefore didn't accumulate any PCB's or pesticides in the first decades of his live. Considering that he started accumulating organochlorines in the 1950's and 1960's, it becomes normal that his contamination levels are similar to the ones of the younger sperm whales, which were born in the 1960's. | |
| + | The low [[PAH]] levels were considered unlikely to affect marine mammals. | ||
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| + | The study concluded that the pollutants present in the sperm whales didn't cause their death, but might have an indirect influence on the health or behaviour of these animals. | ||
| + | <BR> | ||
You can find more information of this study though this [http://www.vliz.be/imis/imis.php?module=ref&refid=6837 link] | You can find more information of this study though this [http://www.vliz.be/imis/imis.php?module=ref&refid=6837 link] | ||
Revision as of 10:36, 3 July 2009
Heavy Metals, Organochlorines and Polycyclic Aromatic Hydrocarbons in Sperm Whales Stranded in the Southern North Sea During the 1994/1995 Winter
Context of the study
In the winter of 1994-1995, 21 sperm whales beached along the North Sea shorelines. The reason for the mass stranding was that these sperm whales became trapped in the North sea. Because of the unfavorable conditions in the North Sea the animals starved and ultimately stranded. These animals can be used to obtain valuable information on accumulation and excretion mechanics of stable pollutants and the overall health status of these long-living marine mammals.
Content of the study
7 of the 21 sperm whales beached on Belgian and Dutch territory. One of them died at least a day before beaching (possibly of old age, as he was estimated to be at least 60), the six others died shortly after stranding. The muscles, livers kidneys and fat of these 7 whales were examined for the presence of heavy metals, organochlorines and PAH's.
Main results
High concentrations of cadmium (up to 300 µg/g dry weight in the kidney), total mercury (up to 130 µg/g dry weight in the liver) and PCB's (up to 5 µg/g in blubber) were retrieved in these sperm whales. Methylmercury averaged 4% of total mercury concentrations in the liver and 90% in the muscles. Less than 66% of the Cd found in the livers and kidney's were bound to metallothioneins; these are proteins which animals produce to counteract the harmful effects of metals. Therefore the remaining 33% might not have been detoxified.
Organochlorine concentrations in the blubber were found to be low compared to other species. Since similar levels have been shown to have caused reproductive and immune-deficiency problems in marine mammals, this doesn't necessary imply lack of effect.
Although other studies have shown that stable pollutants (like PCB and mercury) tend to accumulate in marine mammals with increasing age, this study didn't find higher concentrations of any contaminant in the oldest animal (the one that died of old age before stranding). Since he was estimated to be at least 60, this means that he was born in the pre-organochlorine period and therefore didn't accumulate any PCB's or pesticides in the first decades of his live. Considering that he started accumulating organochlorines in the 1950's and 1960's, it becomes normal that his contamination levels are similar to the ones of the younger sperm whales, which were born in the 1960's.
The low PAH levels were considered unlikely to affect marine mammals.
The study concluded that the pollutants present in the sperm whales didn't cause their death, but might have an indirect influence on the health or behaviour of these animals.
You can find more information of this study though this link
