PSL280H1 Lecture Notes - Lecture 10: Marine Mammal, Biomagnification, Specific Volume
PSL280 Lecture 10:
• oceans receive many chemicals and compounds
• little definitive proof that pollutants directly affect health or mortality
• must categorically show a specific volume of a contaminant causes a problem
Biomagnification: [pollutant] increasing when moving up the food chain
• dependent on route of exposure, chemical/physical properties of compound
• also depends on metabolic capacity and physiological condition of predator
Bioaccumulation: [pollutant] increasing in one animal over time
• causes impaired reproduction, impaired young development, indirect/direct mortality
• pollution impact depends on organ/system/species affected, what organ stores it
• many factors determine organ/tissue concentrations
• incl. type of food/prey, age of predator, reproductive status
• incl. gender, geographical prey location, feeding habits
A. Heavy Metals (Mercury, Lead, Chromium, Cadmium)
• extremely difficult to study in wild marine mammal species
• difficult to obtain animal samples due to extreme/harsh habitat
• most studies complicated by lack of controlled conditions
• marine mammals have high tolerance of mercury, lead, cadmium
• commonly stored in liver, kidney, muscles
• has been shown to cause developmental impairments, neurological disease
• medical problems translate to humans via biomagnification
• i.e. Minamata disease in Japan
• company dumped methylmercury wastewater into ocean from 30s to late 60s
• shellfish and fish eaten by humans
• ‘dancing cat disease’ - cats found convulsing
• human cost - 2300 severe cases, 1800 early deaths, 10,000+ victims
• symptoms incl. insanity, coma, paralysis, death, loss of muscle control/speech, etc.
• similar issues in Inuit populations in Canada
• marine mammals can demethylate organic mercury to inorganic form
• marine mammals can also combine mercury with selenium producing a salt
B. Organochlorines/Hydrocarbonated Insecticides (DDTs)
• accumulate more in males
• females pass on organochlorines to young through placenta or lactation
• little is known how they affect males, most research on females
• immunosuppressive, make animal vulnerable to bacterial/viral disease
