© 2003. Zakharova N.A., the PhD dissertation topic and synopsis, the Russian Research Institute of Fisheries and Oceanography (FSBSI VNIRO)
The level of accumulation and impact of a number of toxicants on the Caspian seal population status
Since the mid 80-ies of the 20th century, the population of the Caspian seal has been in a depressed state. It was found that the main cause for the population reproduction crisis is anthropogenic pollution of the Caspian Sea ecosystem, which causes cumulative polytoxicosis in the animals.
The author assessed the effect of pollutants (organochlorine pesticides, heavy metals, oil hydrocarbons) on the state of the Caspian seal population, determined the level of their accumulation in the liver and subcutaneous fat, estimated their threshold concentrations affecting the reproductive function of the Caspian seal, revealed correlation links between the level of pollutants and barrenness of Caspian seals as well as the limiting effect of organic and biological pollutants on the Caspian seal population abundance.
The proposed models of links between environmental pollution and barrenness in female seals prove that certain concentrations of organochlorine pesticides (HCCH – 10.6, DDT – 610.0 μg/kg), heavy metals (lead – 0.89, cadmium – 1.0, total mercury – 1.62 mg/kg), petroleum hydrocarbons – 210.0 mg/kg in subcutaneous fat indicate a depressed status of the Caspian seal population. At these levels of pollutants content in seals tissues, the commercial hunting on Caspian seals must be prohibited.
Photo: V. Slodkevich, M. Khrisanova