De L. Swart, R., Peter S. Ross, Lies J. Vedder, Helga H. Timmerman, Seim Heisterkamp, 1994. Impairment of Immune Function in Harbor Seals (Phoca vitulina) Feeding on Fish from Polluted Waters. Ambio 23: 155-159.

• California Sea Lions showed premature parturitions and abortions due to infection of the calcivirius. There has been shown to be a direct correlation between the number of infections and the amount of pollutants in the water.

• Seals from the Baltic Sea have shown reproductive tract and sterility and skeletal deformities related to increased levels of PCBs in the water.

• Seals in a semi-field study who were fed highly polluted fish showed reduced pup production.

Pollutants: Lipophilic Organochlorines

• PCBs - used in electrical and other industrial applications and was previously thought to be non-toxic.

• PCDDs and PCDFs - very toxic chemical from the breakdown of PCBs

• HCB - fungicide

• Dieldrin - insecticide

• Beta-HCH - pesticide byproduct and isomeric impurity (industrial HCH)

• sDDT – insecticide

Evaluate the toxic effects of environmental chemicals on the immune system of harbor seals and possible relation to diseases found in wild populations.

Basics of the harbor seals:

• Captured as weaned pups from relatively unpolluted waters off Scotland.

• Housed at the Seal Rehabilitation and Research Center in Pieterburen

• 52 weeks of diet adaptation with relatively unpolluted Atlantic Ocean herring before experiment started.

• Seals were divided into two groups of 11, matched for sex and weight.

• Diets were stadardized as far as nutritional quality and all were given vitamins once a week.

Basics of the Experiment:

• Group 1: fed herring from polluted Baltic Sea, fed one additional one to compensate for lower lipid content.

• Group 2: fed herring from relatively unpolluted Atlantic Ocean

• Duration of experiment: 93 weeks

• Data: haematological and immunological data taken at intervals of 6 to 9 weeks

Hematological Tests:

• Vitamin A concentrations taken by HPLC analysis of the blood serum after removal of retanoids by hydrolysis.

• White blood cell counts determined in whole blood treated with EDTA (anti-coagulant) by a hematology analyzer which can differentiate also between different leukocytes.

• Reactions of Peripheral Blood Mononuclear Cells (PBMC) to various mitogens. Cells were placed in tubes with the following mitogens to stimulate the immune function. Each test was done in triplicate and mitogens were marked with H³ which consumption of by the cells was used to measure the effectiveness. The mitogens were concanavalin A (Con A), pokeweed mitogen (PWM), phytohaemagglutinin-M (PHA), and lipopolysaccharide from Salomenella (LPS).

• Natural killer cell activity was tested in triplicate by placing them in cultures of YAC cells which are cancerous cells. The cells were labeled with Chromium to deterimne the consumption of them.

Analysis of the herring:

• Random samples taken from each batch of herring used fish homogenated and organochlorine concentrations determined. Each batch was analyzed for PCDDs, PCDFs, and coplaner PCPs. From this daily and monthly organochlorine intake by the seals could be calculated.

• Average weight increased from 44 to 61 kg, primarily due to juvenile growth. The group 1 suffered initial weight loss because they did not eat at the start of the experiment due to change from the Atlantic herring to the Baltic Sea herring.

• The organochlorine intake was shown to be 3 to 10 times higher in group 1 than group 2. Significant differences were calculated using an ANOVA test.

• Vitamin A levels were shown to be significantly lower in the first group of seals.

• White blood counts were significantly higher in group one, which was shown in a significantly increased number of granulocytes. No significant differences were noted in numbers of lymphocytes and monocytes.

• There was a significant decrease in lymphocyte function in group one when exposed to the Con A, PWM, and PHA mitogens. There was no significant difference between the two groups with the LPS mitogen.

• There was a significant decrease of effectiveness in group one when natural killer cells were exposed to the YAC-1 cells.

In group one the high levels of lymphocytes may show that the group was more prone to bacterial infections. Also the first line of defense, the natural killer cells, activity was significantly reduced which could be the cause of increased numbers of other lymphocytes. The lymphocytes in general had a reduced proliferation when exposed to different mitogens showing that the immune system was directly effected.

Whether or not pollution had an effect in recent morbillivirus outbreaks is unsure but the pollution did have an effect on immune system. There have been two, possibly three morbillivirus’ identified. One from striped dolphins in the Mediterranean, Dolphin Morbillivirus (DMV). Porpoise morbillivirus (PMV) was isolated in harbor porpoises off the Irish coast. There has been a strain of morbillivirus of pilot whales isolated which appears to be different then the other two. There has only been one case of morbillivirus in pilot whales reported so there is no definates as to whether the third is real.

Other organisms such as the California Sea Lion have been severely affected by a toxin released by an algal bloom. Whether the algal bloom is a result of the pollution or the California sea lions are having an immune deficiency is yet to be discovered.

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Taubenberger, JK; Tsai, MM; Atkin, TJ; Fanning,TG; Krafft,AE; Moeller, RB. 2000. "Molecular Genetic Evidence of a Novel Morbillivirus in a Long-Finned Pilot Whale (Globicephalus melas)." Center for Disease Control. vol. 6, no. 1

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