1. Case study of Bioaccumulation and Biomagnification– Orcas - endangered species of Puget Sound

2. Orcas (a.k.a. killer whales)
Scientific name: Orcinus orca
Largest member of dolphin family
Identifying traits:
Height of dorsal fin
Saddle patch behind dorsal fin
White patches on sides, belly, behind eyes

3. Orca biology Birth weight: around 400 lbs
Adult weight – between 2.5 – 7 tons
Males larger than females
Lifespan:
Females: can live to over 60 years
Males: live around 40 years

4. Natural History Found in all seas, including Arctic and tropics
Travel in pods: 3 - >150 individuals
Main food:
Fish
Squid
Marine mammals

5. Transient vs. Resident Orcas
2 major subspecies of orca
Transient orcas:
Live offshore
Feed mostly on marine mammals
Small pods of 3-5 individuals
Tend to be very quiet
Resident orcas:
Live near shore
Feed mostly on fish (esp. salmon)
Large pods: >20 individuals
Vocalize often

6. Puget Sound Resident Orcas
Live in extended familial units called pods
Pods are matriarchal in structure
Oldest female is the grandmother of other orcas in pod
Puget sound resident orcas
3 pods – J, K, L
Summer around San Juan islands
Winter on
the outer coast

7. Status of Southern Resident Orcas
: about 20% of southern resident orcas died – now 89 orcas
Many females of reproductive age are not producing viable young
Young males: dying rapidly
Few males left in entire community
Listed as endangered species in 2005 – at risk of extinction

8. Threats to Orcas Decreasing food supply Disturbance
wild salmon are also listed as an endangered species
Disturbance
Physical (harassment by whale watching vessels)
Acoustic (low/mid frequency sonar, drilling, dredging)
Interferes with echolocation
Environmental contamination
Bioaccumulation of pollutants
Historic threats
Hunting
Captured for captivity in marine parks

9. Pollutants
Pollutant: any agent that adversely affects the health, survival, or activities of living organisms or that alters the environment in undesirable ways

10. How do pollutants enter environment?
Point source pollution – specific locations of highly concentrated pollutant discharge
Factories, power plants, sewage treatment plants
Non-point source pollution – scatter, diffuse sources of pollutants
Runoff
farms, roads, golf courses, homes, etc
All pollutants eventually
end up in the ocean

11. Types of pollutants Water soluble pollutants Fat soluble pollutants
Move rapidly and widely thru an environment
Fat soluble pollutants
Inside organisms, they penetrate readily into tissues and cells
Stored in lipid deposits
Protected from metabolic breakdown
Passed via breast milk to young in mammals
Tend to have much longer effects

12. Pollutant persistence
Persistence = how long it takes to breakdown and be removed from the ecosystem
Some compounds are very unstable and degrade rapidly
Concentrations decline rapidly over time
Other compounds are specifically designed to resist degradation (don’t break-down easily)
Can have severe impacts long after they are introduced

13. POPs Persistant Organic Pollutants
synthetic organic compounds used in various products (from electronics to cars) that resist environmental degradation
Include PCBs and DDT
Can have very long term effects in affected ecosystems

14. PCBs: Polychlorinated biphenyls
BOTH FAT SOLUBLE AND A POP = very stable and resists degradation
Used in: transformers, pesticides, paint, small electric parts, etc from
Enter mainly through non-point sources: products with PCBs leak, PCB travels into soil, carried by wind and water into environment (and eventually the ocean)
In rats – cause liver cancer, pituitary tumors, leukemia, lymphoma and intestinal cancer
In humans, classified as a probable human carcinogen (cancer causer) → banned in 1977

15. Bioaccumulation
Process by which cells selectively absorb and store a great variety of molecules
Allows cell to accumulate nutrients and essential minerals (like calcium, phosphorus, etc.)
However, same process can also absorb and store harmful pollutants inside an organism
Reason some fish are not fit for human consumption (usually because of bioaccumulation of mercury)

16. Biomagnification
Process by which the effects of pollutants are magnified up an ecosystem through food chains
When organism consumed by a higher trophic level, only about 10% of energy moves up, however majority of the pollutant is passed on from prey to consumer
Therefore – as the pollutant moves up the food chain, the concentration of the pollutant in the body tissue increases dramatically
This is especially true for POPs since they persist for long periods of time

17. Biomagnification Example DDT residues - Long Island Estuary Woodwell, Wurster, Isaacson, 1967
Trophic level
Organism
DDT (wet weight)
Primary
Producer
Green alga
0.08 ppm (parts per million)
Consumer
Mud snail
0.26 ppm
Secondary
Summer Flounder
1.28 ppm
Tertiary
Ring-billed gull
75.5 ppm

18. Puget sound orcas affected by PCB’s
Our orcas have, on average, the highest measured levels of PCB’s of any marine mammal IN THE WORLD
Almost 150 ppm (parts per million) average
>10 ppm PCB known to cause immune problems in seals
Mother can pass as much as 90% of PCB’s to her offspring via milk and through placenta
Female transient orca found dead on Dungeness spit in 2002 had 1000 ppm

19. Yeah, but there are banned, right?
Double whammy for our orcas
PCB’s are less harmful when in fat vs. their bloodstream
Low salmon runs = orcas use blubber (fat) for energy ↓
PCB’s released into blood
PCBs interfere with normal immune function
Result: orcas more susceptible to disease and pathogens

20. Yeah, but PCB’s are banned, right? - other POP’s – the ‘Dirty Dozen’
POP (persistent organic pollutant)
Pesticide
Industrial Chemical
By-product
Aldrin √
Chlordane
DDT
Dieldrin
Endrin
Heptachlor
Mirex
Toxaphene
Hexachlorobenzene
PCBs
Dioxins
Furans

21. New era, new threats
Many countries still use chemicals that have proven to bioaccumulate
Chemicals are stored all over the world and are often not properly disposed of
US does not have a law that insists on testing of new chemicals (unless they are used in food)
Only 10% of the 85,000 chemicals used in North America have been tested for environmental effects

22. PBDEs: example of a new threat
Polybrominated diphenyl ethers
Group of fire-retardant chemicals (they don’t catch fire)
A POP: structurally similar to PCB’s
Found in furniture, televisions, computers
Europe has banned PBDE’s, only state to ban is California
There IS an available fire retardant shown not to bioaccumulate

23. Extra credit Research report on:
PBDE’s or another currently used pollutant
Use at least 3 different sources (and provide bibliography)
Include:
Chemical structure
What it is used in/ for (pros)
Environmental/ health impacts (cons)
Statement on whether you believe it should continue to be used or outlawed