1. science
2. ecology
3. pollution

Happy Orcas
Dead Orcas
State of Southern
Resident Orcas
• Almost 20% orcas died between
1995 and 2000.
• Reproductive females have not
produced young in ten years.
• Only four adult males in the
entire community of 80 whales.
Puget Sound
Orcas and PCBs
• Highest levels of PCBs in
blubber of any marine mammal
in the world
– Average almost 150 ppm
– <10 ppm PCB is known to cause
immune problems in seals
• Dead female transient orca on
Dungeness Spit in May 2002
– 1000 ppm PCB
– 12ppm- EPA’s standard for
marine sediments
Polychlorinated
Biphenyls
(PCBs)
Cl
Cl
Cl
Cl
PCBs
• Highly stable oily fluids and solids
– Transformers, pesticides, etc
• Fat soluble
– Reside in fatty tissue
• Block hormone activity
– Destroy normal immune function
– Cause liver cancer, pituitary tumors,
leukemia, and lymphoma
• Banned in U.S. since 1977
Ecosystem Review
• Ecosystem
– Organisms interacting with
environment and each other
through a food chain
• Food Chain
– Biomass moves from one
organism to another as each eats
a lower member and, in turn, is
eaten by a higher member
Generalized
Ecological Pyramid
Idealized Puget Sound
Ecological Pyramid
Pollutants
• Pollutant
– Adversely affects the health,
survival, or activities of
living organisms
– Persistent Organic Pollutant
• POP
• Stable, Long Lasting
• Includes DDT and PCBs
Sources of Pollutants in
the Environment
• Point Source
– Specific location of
concentrated pollutants
• Factory waste
• Sewage
• Nonpoint Source
– Scattered or diffuse sources
of pollutants
• Golf courses
• Agriculture
Factors Influencing
Impact of Pollutants
• Solubility
– Water soluble pollutants
• Move easily through environment
– Fat soluble pollutants
• Need a carrier
• Long-lasting in body’s fatty tissue
• Persistence
– More stable
– Longer to break down
– More harm it can do
Pollutants in the
Food Chain
• Bioaccumulation
– Cells increase the concentrations
of molecules relative to the
environment
• Biomagnification
– Concentration of pollutants
increases as they move up the
ecological pyramid
– Only 10% of biomass, but most of
the pollutant is transferred
DDT in a Long Island
Estuary
(from Woodwell, Wurster
and Isaccson, 1967)
Trophic
level
Organism
DDT in wet weight of
whole organism
Primary
Producer
Green
Alga
0.08 ppm
Primary
Consumer
Mud
Snail
0.26 ppm
Secondary
Consumer
Summer
Flounder
1.28 ppm
Tertiary
Consumer
Ringbilled
Gull
75.5 ppm
(About 1000x Initial
Concentrations!)
Idealized Puget Sound
Ecological Pyramid
With PCBs
Trophic Level
Phytoplankton
Zooplankton
Salmon
Orcas
%PCB
0.1%
1%
10%
100%
The ‘Double Whammy’
• In blubber, PCBs are not very
harmful.
• Low salmon runs force orcas to
metabolize more blubber to
survive.
• The blubber releases PCBs into
the blood, destroying the
immune system.
• Therefore, starvation increases
the lethality of the pollutant.