Contaminants

• Biomagnification = increasing conc. of compound or pollutant as it passes up the food chain
• Variables that increase biomagnification

  1. route of exposure
  2. chemical and physical properties of the compoud
  3. metabolic capacity of predator

  • if you have an enzyme that breaks down combound then it decreases magnification as it is broken down

  1. predators physiological condition

  • if an animal is already weak or has a problem the pollutant will have more of an effect
• Impact of pollutants on marine mammals:

  1. impaired reproduction = lowered reproductive success, anything from conceiving, development of fetus, and giving birth to viable fetus and it surviving
  2. indirect mortality = disease or weakened immune system
  3. direct mortality = acute chemical poisoning or physical effect
• Impact of pollution depends on:

  • the organ or system affected
  • the organs where the pollutant is stored
  • the species affected
• key factors that determine organ/tissue conc./ of pollutants

  • type of food/prey (algae versus fish)
• key factors that determine organ/tissue conc./ of pollutants

  • age of predator (young versus old)
  • accumulating it for the entire life or like where’s it coming from, maybe from blood in placenta
• key factors that determine organ/tissue conc./ of pollutants

  • reproductive status (lactating versus pregnant)
  • lactating will feed onto young and pollutant dependent because not all will be transferred onto young
• key factors that determine organ/tissue conc./ of pollutants

  • Gender
  • hormonally different so could be processed differently and also only females have babies
• key factors that determine organ/tissue conc./ of pollutants

  • geographical location of prey
  • if near the coast you could have higher conc. of pollutants compared to deep ocean, not always but most likely
• key factors that determine organ/tissue conc./ of pollutants

  • Feeding habits
  • herbivore eats large volumes but at bottom of food chain, larger hunters such as seals will eat larger animals and get more of accumulation
• Impact on species- what usually affects specific species the most:

  • impaired reproduction - seals
  • impaired development in young - polar bears
  • indirect mortality - dolphin, ingestion
  • direct mortality - sea otter, thermoregulation from oil on fur
• Heavy metals - mercury, lead, chromium, cadmium, etc
• Heavy metals

  • difficult to get samples due to extreme or harsh habitats
  • most studies are complicated by lack of controlled conditions
  • marine mammals have ability to tolerate high amounts of heavy metals like mercury or cadmium
• Heavy metals

  • commonly stored in liver, kidney, and muscles. Some marine mammals species, mercury can cause neurological problems or results in young being unable to develop normally
• Heavy metals

  • medical problems are also seen in humans who eat contaminated marine mammals with mercury → Minamata disease in Japan or some indigenous communities
• • Minamata disease → company was dumping wastewater with methylmercury, shellfish and fish eaten by humans caused dancing cat disease= cats convulsing in the streets
  • Symptoms: insanity, coma, paralisis, death, loss of muscle control and speech ability
• • marine mammals can detoxify mercury by:

  1. demethylating the organic mercury into less toxic inorganic mercury
  2. combining mercury with selenium which produces inactive salt
• organochlorines or hydrocarbonated insecticides (DDTs)

  • compounds usually accumulate more in males than females as females reduce their organochlorine levels by passing pollutants to their young through placenta or lactation
• organochlorines or hydrocarbonated insecticides (DDTs)

  • little known how organochlorines may affect males as studies looked at females
  • may affect immunosuppressive system of the animal making it more vulnerable to diseases
• organochlorines or hydrocarbonated insecticides (DDTs)

  • in polar bears found high concentrations of organochlorines, female bears have normal vaginal opening but also small penis with no baculum and no Y chromosome
  • harbour seals fed BPCs and a specific type of DDT, reproductive rate showed a 60% drop in births
  • in cetaceans it is unclear how it affects them, suggested that PCBs can induce enzymes leading to endocrine imbalance
• organochlorines or hydrocarbonated insecticides (DDTs)

  • in cetaceans it is unclear how it affects them, suggested that PCBs can induce enzymes leading to endocrine imbalance
• organochlorines structurally affects organs such as kidneys, adrenal glands and reproductive tract but usually stored in fatty tissues such as blubber, liver and brain
• persistent organic pollutants PCBs

  • PCBs used in dielectric fluids in transformers and capacitors but also found in plastic breakdown
• persistent organic pollutants PCBs

  • have become one of the most common and abundantly reported contaminant in marine mammals
  • have been found in blubber of thousands of animals since mid 60s
• persistent organic pollutants PCBs

  • highest conc. normally in males and diseased individuals
  • usually in species closest to sources such as seals, sea otters, and polar bears
• • reproduction, impaired growth and brain are affected by PCB contamination
  • can affect thyroid hormone transportation in the brain and could impact hearing → important to locate food
• • petroleum products - crude oil, gasoline
  • usually have dramatic affect within geographical area of the spill such as sea otters in alaska
  • Exxon Valdez oil in 89 is site of one of the largest and most damaging oil spill
• • oil comes in various forms and properties
  • crude oil is divided into different categories
  • light, medium or heavy
  • each react differently when spilled into water
  • some float and evaporate, sink below surface, some sink to the bottom
• each form of oil will move differently with currents and tides, difficult to study direct and indirect effect due to diff properties
• • within first few hours or days of spill:
  • light oil types will be most acutely toxic
  • vapours may be breathed in and irritate or burn tissues (eyes, mouth, lungs)
  • can be ingested from grooming or during feeding and be absorbed into the blood and damage the liver or NS
  • sea otters in Exxon Valdez spill were lethargic, respiratory disease, diarrhea, and liver or kidney failure, many dead ones also had brain lesions probably from inhaling vapours
• • oil causes hypothermia → in sea otters, polar bears and seals can lead to death
  • thick oil coats the fur and causes hairs to stick together → loss of thermal regulation
• 300 Million tons of plastics produced globally, 8 million ends up in oceans each year → can last up to 450 years in environment
• • PFCs perflurocarboons ex. PFOS
  • teflon, carpet treatments, firefighting foam, etc
• • Micro/nano plastics
  • micro plastics = <5mm size
  • nano plastic = 1-100nm size
• • PAHs
  • found in oil, gasoline, coal
  • also released with improper burning of fuels and garbage
• • specific contaminant or the amount of contaminant may affect a species in different degrees
  • age
  • fat reserves
  • breeding stage
  • prey
• contaminant may be affected by other chemicals such as neutralizing affect of selenium on mercury, could also be a mixture of pollutants such as PCBs