Lecture 10 (Contaminants) Flashcards
What is Bioaccumulation?
- refers to a pollutant increasing in concentration within one singular animal over time
Have we found any definitive proof that pollutants directly affect the health of marine mammals or what role they play in mortality?
NO
What is biomagnification?
- Pollutants can be passed from prey to predator through the food chain
- Passing from one animal to another
What are the variables that can affect and increase biomagnification?
- Route of exposure
- The chemical and physcial properties of the compound/pollutant
- The metabolic capacity of the predator (enzymes)
- The predators physiological condition
What are the three general impacts of pollutants on marine mammals?
- Impaired reproduction (lowered reproduction success)
- Indirect mortality (disease or weakened immune system) –> reducing overall health
- Direct mortality (acute chemical poisoning or physical effects)
What general aspects of the body do the impact of pollution also depend on? (3 things)
- The organs or systems affected
- The organs where the pollutant is stored
- The species affected
What are some key factors that determine organ/tissue concentrations of pollutants? (6 things)
- Type of food/prey (algae vs fish)
- Age of predator (young vs old)
- Reproductive Status (lactating vs pregnant)
- Gender (male vs female)
- Geographical location of prey (higher concentration in rivers/bays vs deep ocean)
- Feeding habits (herbivore, larger hunters such as seals)
What are the impacts of pollutants on species with specific examples?
- Imparied reproduction (seals)
- Impaired development in young (polar bears)
- Indirect mortality (dolphin- ingestion)
- Direct mortality (sea otter - thermoregulation)
What are the categories of chemical pollutants? (4 things)
- Heavy Metals (mercury, lead, chromium, cadmium, etc)
- Organochlorines or hydrocarbonated insecticides (DDTs)
- Persistent organic pollutants (PCBs)
- Petroleum products (crude oil, gasoline)
How do marine mammals react to heavy metals compared to humans
- Marine mammals can tolerate higher levels of heavy metals
What are three reasons why heavy metal pollution is extremely difficult to study?
- Difficult to obtain animal samples due to extreme or harsh habitat
- most studies are complicated by lack of control conditions
- Marine mammals have the ability to tolerate high amounts of heavy metals
Where are heavy metals commonly stored in marine mammals?
- stored in the liver, kidney, and muscles
- Lead in bones
In some marine mammal species, what affect does mercury have?
- cause neurological diseases
- results in youth development abnormalities
How does mercury contaminated marine mammal products affect humans?
- Similar neurological diseases occur
How can marine mammals detoxify mercury?
- Demethylation (removal of CH3 group)
- highly toxic organic mercury converted to less toxic inorganic mercury - Combining mercury with selenium producing an inactive salt
How do organochlorines and hydrocarbonated insecticides (DDTs) affect males differently from females?
- Accumulate more in males than females
- Females reduce their organochlorine levels by passing pollutants to young in placenta
What is a hypothesized method that organochlorines and hydrocarbonated insecticides (DDTs) work?
- Pollutants may affect the immunosuppressive system of the animal making it vulnerable to disease
When polar bears are affected by oganochlorines and hydrocarbonated insecticides (DDTs) what happens? What is unique about polar bears and this pollutant specifically?
- Marine mammal where highest concentrations of organochlorines have been found
- Females have normal vaginal opening BUT small penis with no baculum, no Y chromosome
What was the specific study done on harbor seals which revealed a specific effect of DDT however it was unethical?
- Harbor seals fed PCBs and a specific type of DDT
- Reproductive rate showed a 60% drop in pup births
- Other pinniped species showed similar results
How do organochlorines and hydrocarbonated insecticiedes (DDTs) affect cetaceans?
(What are the suggested effects and which enzyme)
- Still unclear
- Suggested that PCBs induce enzymes leading to endocrine imbalances
- Cytochrome P450
Which organs do organochlorines affect and where are they stored?
Organs:
- Kidneys, adrenal glands and reproductive tract
Stored:
- fatty tissues such as blubber, liver, and brain
What were the highest levels of organochlorides reported AND in which cetaceans?
Killer Whale
900ug/g
(900 times more than normal)
What are PCBs?
- Persistent organic pollutants
- Polychlorinated biphenyl - used in dielectric fluids in transformers and capacitors
What are the most common and abundantly reported contaminant in marine mammals?
PCBs
Since the mid-1960s, where have PCBs been found in marine mammal anatomy?
Which sex has a higher concentration?
- found in the blubber of thousands of marine mammmals
- Highest concentrations found in males and diseased individuals
What species are PCBs usually found in?
- Seals
- Sea Otters
- Polar Bears
What do PCBs impair?
- growth in young
- Brain function
What have recent studies suggested regarding how PCBs affect the body?
Why are the results important?
- Affect thyroid hormone transpot in the brain impacting hearing
- important as numerous species of marine animals depend on sound/hearing to locate food
What is unique about how petroleum products affect marine mammals?
- affect marine mammals within geographic area of spill
What was the largest and most damaging oil spills?
- how many marine mammals died
- Exxon Valdez oil spill (1989)
- estimated 3,000-5,500 sea otters and 300 harbor seals died
What are the various forms that oil comes in?
- Differs in viscosity (thickness) and specific gravity (weight)
What categories are crude oil divided into?
How do each react when spilled in water?
- Light -> Float or evaporate
- Medium -> sink just below surface
- heavy -> Sink to the bottom
Why is it difficult to study the direct and indirect effects of oils?
Each form of oil will move differently with currents and tides
What determines how detrimental the oil spill will be?
- The composition of the oil
- Enviornmental conditions
- Marine mammal species involved
Which type of oil will be more toxic in the first few hours or days of a spill?
- Lighter oil types are more acutely toxic
In what ways can oils cause harm internally?
- Vapors may be breathed in and irritate or burn tissues (eyes, mouth, lungs)
- Ingested from grooming or during feeding then absorbed into blood, damaging liver or nervous system
What were the symptoms of the sea otters affected in the Exxon Valdez Oil spill?
- Sea otters were lethargic
- respiratory distress
- diarrhea
- liver/kidney failure
What happened to the seals in the Exxon Valdez oil spill?
- Dead seals had brain lesions
- thought to have come from inhaling oil vapors
What can oil do to marine mammals in terms of their fur?
- Causes hypothermia (low body temp)
- Sea otters, polar bears, and seals can die
- oil causes hair to stick together resulting in a loss of thermoregulation (detrimental to sea otters as they do not have fat or blubber storages)
How much plastic is produced per year and how much ends up in the ocean? How long does it last?
- 300 million tons produced
- 8 million tons ends up in the ocean
- Lasts up to 450 years
What are the new pollutants?
- PFCs
- Micro/nano plastics
- PAHs
What is a PFC?
-(Perflurocarbons)
- teflon, carpet treatments, firefighting foam
What are the smallest pollutants?
Micro/Nano plastics
- Micro plastics = <5mm
- Nano plastics = 1-100 nm size
- In 2014 = 15-51 trillion pieces of nanoplastics; 93-236,000 metrict tons
What are PAHs
Polycyclic aromatic hydrocarbons (ending in ene)
- found in oil, gasoline, coal
- released with improper burning fuels, garbage
What are the factors that determine how a specific contaminant or amount of a contaminant affects a species?
- Age
- Fat reserves
- Breeding stage
- Prey
How can a marine mammal metabolically neutralize a contaminant?
- Contaminants may be affected by another chemical
- Selenium converts mercury to non toxic salt
- Selenium may mix with other pollutants such as PCBs
Why is studying pollutants and their effects very important?
- Effects on environment is highly speculative
- many factors
- little research
