Bioaccumulation: A case study of British Columbia's killer whales

Lesson 1 - Natural history of British Columbia's killer whales

Activity description

1. Review with students the natural history of British Columbia's killer whales. [with PowerPoint slides, if internet is available]
   • Three types of killer whale 
   • How to tell killer whales apart (Dorsal fins and saddle patches are like human fingerprints: all different).
   • Resident killer whale diet and social structure
   • Concept of "matrilines" (like a family tree for humans)
   • Transient killer whale diet and social structure
2. Provide Student Handout: Lesson 1 to each student.
3. Have students do questions 1-6 in class, and discuss as a class.

Student handout 1 - The different populations of killer whales in British Columbia

Cetacean: is the name for the group of mammals that are whales, dolphins and porpoises.

Remember that mammals:

• Are able to keep their internal temperatures constant (they are homeothermic)
• Give birth to fully developed young
• Nurse their young
• Have lungs

Most mammals have hair that traps air for warmth. Cetaceans do not have hair but blubber for warmth. Hair would not work to keep them warm since hair cannot trap air in the water. The hair would actually slow them down!

Killer whales (or Orca) are the biggest members of the dolphin family. They are toothed cetaceans and are extremely intelligent and social animals.

They were named killer whales as they were all thought to be killers of other whales. Their scientific name Orcinus orca also reflects misunderstanding as it loosely translates into "hell creature".

Killer whales can be found in all marine waters of the world but more often in colder seas. All over the world, populations of killer whales have developed different lifestyles depending on the geography and food availability of their area.

We know what we do about killer whales because of the work of Dr. Michael Bigg. Back in the 1970s, it was believed that there were thousands of killer whales in British Columbia and that they should be shot because they were eating too much salmon. Killer whales were also being captured for aquariums. Dr. Bigg found a way to tell killer whales apart so that they could be counted accurately. He did this using the whales' saddle patch and dorsal fin. He catalogued the animals and proved that people were often seeing the same killer whales again and again. There were only hundreds of them, not thousands. His work led to stopping of the shooting and capture of killer whales.

Once he could study killer whales as individuals, Dr. Bigg also found out that there were different kinds. We now know that there are 3 different kinds (eco-types) of killer whales in the waters of British Columbia that do not mate with one another. They have different diets and distinct behaviour and culture.

The three eco-types of killer whales are offshores, transients and residents. There are two resident populations in British Columbia: northern residents and southern residents. None of these populations mate with one another even though their ranges overlap. Their different languages stop them from mating between populations. Since they do not mate with one another, on average, they look different. For example, transients have more pointed dorsal fins and offshores appear to be smaller animals.

Not much is known about the offshores yet as they are not often seen close to the coast of British Columbia.

Transients feed on marine mammals. They do not eat fish. They have to be very quiet because their marine mammal prey can hear them and recognize that the sounds of transients mean they are in danger. Transients therefore also dive longer and do not travel in big family groups.

Resident killer whales feed on fish. In fact, about 98% of their diet is salmon. They do not eat marine mammals. They can afford to be very vocal since fish cannot hear them. They are very social and often travel in big groups. They have very structured family units called matrilines (mother, her offspring and her daughters' offspring). Neither males nor females leave the matriline. They do not mate within the family (they do not interbreed) since they can recognize who is and is not family because every matriline sounds different. If they sound exactly the same, they stay together but do not mate with one another. They mate with animals of the same population that sound different. Mated males and females do not stay together as a family. They stay in their matrilines so that family sounds remain distinct and the system of recognizing otherness remains intact. The matriline is named for the eldest female.

Not all killer whales in the world are resident, transient or offshore types. They have lifestyles that suit the prey and geography of their area.

Sources: The work of Dr. Michael Bigg; Dr. John Ford; Graeme Ellis and Dr. Lance Barrett-Lennard

The A30 Matriline Note: The names in quotations are assigned by the Wild Killer Whale Adoption Programme after the calves have been sighted for 2 years in a row. This is done because the death rate can be high in the first years of killer whale calves’ lives. 

Questions:

1. What is the relationship between A30 and A75 in the matriline example?
2. Even though A6's body has never been found, how is it known that he is dead?
3. Why isn't it known whether A75 is male or female?
4. Why can resident killer whales afford to travel in large groups and be veryvocal?
5. Why can't transient killer whales be highly vocal animals that travel in large groups?
6. How are residents able to recognize if they are closely related to other killer whales? This is how they avoid inbreeding and why they must stay in matrilines.
7. In 2006, why hadn’t the Wild Killer Whale Adoption Programme given A84 a name and included the animal in their symbolic adoption programme.

Evaluation/assessment tool #1

Questions and answers

1. What is the relationship between A30 and A75 in the matriline example?

A30 (Tsitika) is the grandmother of A75 (Cedar).

2. Even though A6's body has never been found, how is it known that he is dead?

Since residents always travel with their families in matrilines, if an animal is not in the area with his family, he is dead. Scientifically, they are said to be “missing” for a year and then presumed dead. [There are some extreme exceptions like the young whales A73 (Springer) and L98 (Luna).] 

3. Why isn't it known whether A75 is male or female? 

• A75 is too young to see if it does or does not grow the large identifiable dorsal fin of males. Males do not begin to “sprout” until the age of puberty. [If A75 is female, she is also too young to have a calf which would conclude that she is female]
• DNA testing has not been done 
• The pelvic area (underside of the animal) of the individually identified animal has not been seen. The white pigmentation in this area is different in males and females

4. Why can resident killer whales afford to travel in large groups and be very vocal?

• Large groups: Their food supply is usually in large numbers and is predictable (the salmon spawn)
• Vocal: Fish cannot hear the killer whales’ calls

5. Why can't transient killer whales be highly vocal animals that travel in large groups?

• They can’t make a lot of sound because their marine mammal prey can hear the calls and will try to get away
• If they are in large groups, they would be more easily detected

6. How are residents able to recognize if they are closely related to other killer whales? This is how they avoid inbreeding and why they must stay in matrilines.

• They can judge degree of relatedness by sound. If they sound exactly they stay in matrilines but do not mate
• If they sound different (but are member of the same population) they may mate but must stay with their matriline. There is no pair bonding
  - mothers and fathers do not stay together since the system of distinct sounds would then fall apart

7. In 2006, why hadn’t the Wild Killer Whale Adoption Programme given A84 a name and included the animal in their symbolic adoption programme?

Many calves die in their first two years. If the young calf were in the adoption programme and would die, this would lead to complications.

Lesson 2 - The roles of the killer whales in the ecosystem

Activity description

1. Review with students the concepts of food chains and food webs. [with PowerPoint slides, if internet is available]
   1. Food chains of resident and transient killer whales
   2. Food webs
2. Provide Student Handout: Lesson 2 to each student. 
3. Have students do questions 1-5 in class, and discuss as a class.
4. Play the "Food Chain Game". Adaptation of the Ohio Sea Grant Education Program’s activity "How do toxins move through the food chain" and Project Wild's activity "Deadly Links"

Student handout - Killer whale food chains and food webs

An ecosystem is all the organisms interacting with one another and the non-living factors (light, soil, temperature, water) in their environment.

Predators are animals that eat other animals.

Prey are the animals that get eaten by predators.

Producers are organisms that can make their own food. Plants are the main producers. They trap energy from the sun and store the energy in the form of sugar. This process is called photosynthesis. The light energy gets trapped in the bonds of the sugar molecules. 

Consumers are organisms that get energy from eating other organisms. Types of consumers:

• herbivores eat only producers (plants)
• carnivores eat other consumers. Carnivores are predators (e.g., transient killer whales) that eat prey (e.g., seals)
• omnivores eat producers and consumers
• decomposers are consumers that feed on dead organisms. Bacteria and fungi are decomposers. They "clean up" by turning dead organisms back into nutrients in the ecosystem. They are different from scavengers like eagles and hermit crabs because decomposers grow in or on the dead or waste matter taking the nutrients directly into their cells. This is how they recycle nutrients in the environment.

Food chains

A food chain is a model that shows how energy stored in food passes from organism to organism. The arrows show the flow of energy; they point from what is eaten to what eats it. Here is an example: 

In the example, the food chain shows that zooplankton get energy by eating phytoplankton; herringget energy by eating zooplankton; salmon get energy by eating herring; seals get energy by eating salmon; and transient killer whales get energy by eating seals.

At the beginning of a food chain, there are always the producers since they are the only ones that can make their own food from the sun’s energy. Remember, phytoplankton are plants so they are producers!

The consumers that eat the producers are the first order consumers (or primary consumers). The consumers that eat these consumers are the second order consumers (or secondary consumers) and so on.

Food webs

A food web is a model that shows the interactions between food chains. It is a combination of many different food chains that shows the inter-relationships between many producers and consumers in an ecosystem.

Lesson 2: Evaluation/assessment tool

Questions

1. Draw a food chain for resident killer whales

2. In the food chain for resident killer whales:

1. Circle the producer(s)
2. Put a check mark above the consumers
3. Put a square around the prey of salmon
4. Put a star over zooplankton's predator

3. Draw a food web for the following organisms in the space below: Herring; salmon; zooplankton; phytoplankton; transient killer whale; humans; resident killer whale; harbour seal. Hints: Seals eat herring and salmon and so do we. Very few of us eat seals so do not include this link. Transients do not eat humans!

4. How many food chains are there is this food web?

5. Describe where the decomposers would be in this food web.

Answer key

1. Draw a food chain for resident killer whales:

2. In the food chain for resident killer whales:

1. Circle the producer(s)
2. Put a check mark above the consumers
3. Put a square around the prey of salmon
4. Put a star over zooplankton's predator

3. Draw a food web for the following organisms in the space below: Herring; salmon; zooplankton; phytoplankton; transient killer whale; humans; resident killer whale; harbour seal. Hints: Seals eat herring and salmon and so do we. Very few of us eat seals so do not include this link. Transients do not eat humans!

4. How many food chains are there is this food web?

There 5 food chains are in this food web.

5. Describe where the decomposers would be in this food web.

The decomposers would get energy from every organism in the food web once it dies. To add them to the food web, one would draw an arrow going to them from every organism in the food web.

Lesson 3: SARA and threats to killer whales

Activity description

1. Review with students the Species at Risk Act and threats to killer whales
   • Species at Risk Act and its purpose
   • how British Columbia's killer whales are listed according to SARA
   • what the threats are to British Columbia's killer whales
2. Provide Student Handout: Lesson 3 to each student
3. Have students do questions 1-3 in class, and discuss as a class

Student handout - SARA and threats to killer whales

Killer whales in trouble

In 2001, the Committee on the Status of Endangered Wildlife in Canada determined:

• southern resident killer whale are "endangered"
• northern resident killer whales are "threatened"
• transient killer whales are "threatened"
• offshore killer whales are "of special concern"

The transient population and both resident populations are listed in Schedule 1 of the Species at Risk Act (SARA), Canada's law to protect wildlife species from becoming extinct.

Southern resident killer whales travel in both Canadian and American waters. In November 2005, America also listed this population as 'endangered' according to their laws.

Questions

1. What are some possible threats to all British Columbian killer whale populations?

2. Why might transient killer whales be more disturbed by noise?

3. Why might southern resident killer whales be in more trouble that other BC killer whale populations?

Background information

The Species at Risk Act: Working together to Protect Aquatic Species

The Species at Risk Act (SARA) was created to protect wildlife species from becoming extinct in two ways:

• by providing for the recovery of species at risk due to human activity and
• by ensuring through sound management that species of special concern don't become endangered or threatened

The Act became law in June 2003. It includes prohibitions against killing, harming, harassing, capturing or taking species at risk.

A collaborative effort

Three government departments are directly involved in protecting species at risk: Environment Canada, Parks Canada, and Fisheries and Oceans Canada. Fisheries and Oceans is responsible for all aquatic species, freshwater and saltwater alike. 

From the beginning, it was recognized that no single government, industry or community could protect Canadian species at risk on its own. Governments and stakeholder groups across Canada must all work together. In fact, SARA was designed to encourage such cooperation. 

The good news is that everyone can help in some way: by knowing the species at risk and understanding why they're threatened (for example), or by taking steps to care for their habitat.

How does a species get on the list?

Species are designated "at risk" by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC), an independent body of experts that assesses wildlife according to a broad range of scientific data. The federal Cabinet then decides whether those species should get legal protection under the Act. These decisions are made after consultations with affected stakeholders and other groups.

Species can be listed as:

Extinct: no longer found anywhere on the planet.

Extirpated: no longer in the wild in Canada, but existing in the wild elsewhere.

Endangered: a wildlife species facing imminent extirpation or extinction. (The species could soon become extirpated or extinct).

Threatened: likely to become endangered if nothing is done to reverse the factors leading to its extirpation or extinction.

Special concern: a wildlife species that may become a threatened or endangered species because of a combination of biological characteristics and identified threats.

More information about Species at Risk can be found at http://www.sararegistry.gc.ca/default.asp?lang=En&n=24F7211B-1

Threats to killer whales

The current threats to resident killer whales are broadly defined as being:

• environmental contamination
• reductions in the availability or quality of prey
• disturbance - both physical and acoustic disturbance

Historic threats that affected killer whale populations include culling and being taken for captivity. It is important that students gain an understanding that not just one threat is having an impact on killer whale populations. Rather, multiple threats interact to create stresses on the populations. Current research (Dr. John Ford and Graeme Ellis) indicates that both southern and northern resident population declines coincided with a decline in Chinook salmon stocks. The effect was more pronounced in the southern resident population. With less food, toxins are more likely to metabolize and stresses such as noise and boat traffic are likely to have a greater impact as they reduce the chance of catching limited prey. 

Lesson 3: Evaluation/assessment tool

Answer key

1. What are some possible threats to all British Columbian killer whale populations?

• Loss of habitat
• Disease (biological pollution)
• Climate change
• Entanglement
• Ship strike (boat collision) 
• Noise (Acoustic disturbance = boats, seismic activity, low - mid frequency sonar, drilling, dredging, etc.)
• Over-fishing / changes in prey availability
• Human interaction / physical disturbance
• Historical capture for aquariums
• Culling (that they used to be shot at)
• Contaminants (toxins, oil spills)

Note that both resident populations declined when there was a crash in Chinook stocks in the late 1990s. The effect was more pronounced in the southern resident population. Again, it is important that students recognize that these stresses interact to threaten killer whale populations.

2. Why might transient killer whales be more disturbed by noise?

• Transient killer whales need to detect their prey by hearing them
• Noise could mask the sound of their prey so that the transients can't find their food

3. Why might southern resident killer whales be in more trouble that other BC killer whale populations?

Because southern resident killer whales are often in an area with more people, there may be:

• less food
• more pollution
• more noise and stress from boats

There were more southern residents taken into captivity, more may have been shot [and they may be eating food that is more contaminated, possibly from sources far away.]

Lesson 4: Bioaccumulation and killer whales

Activity description

1. Review with the students concept of bioaccumulation.
   • what is bioaccumulation
   • what persistent organic pollutants can do to an organism
   • where POPs come from
   • the implications of different PCB levels in British Columbia's killer whale populations
   • how levels of toxins in organisms increase up the food chain
    
2. Provide Student Handout: Lesson 4 to each student
3. Have students do questions 1 to 7 in class. Questions 5 to 7 can be adapted to be class discussion questions
4. Play the "Food Chain Game with Toxins ".
5. Have students complete question 8

Student handout - What is bioaccumulation?

Many chemicals we use in our daily lives are toxic. Toxic chemicals include pesticides, engine products and many household cleaners. Most toxins are made by humans; they do not occur naturally.

Some of these toxins are persistent. This means that they do not break down and as a result they build up in the food chain. They usually build up in the fat of organisms. The mother's milk of mammals has lots of fat in it. 

The build up of toxins in organisms is called bioaccumulation.

Persistent toxins are also known as Persistent Organic Pollutants (POPs).

Persistent toxins can cause the following problems:

• reproductive failure
• birth defects
• immune system disorders (cancers and weakness to disease)
• behaviour and learning disorders
• Death

The more toxins an organism has, the greater its problems. 

We may use toxins on land, but they go through the soil to the groundwater and into the ocean. All persistent toxins eventually end up in ocean food chains. 

The diagram below shows what bioaccumulation means for killer whales. Transient killer whales would have more persistent toxins because they are higher in the food chain than resident killer whales. Since resident killer whales and seals are both 4th order consumers, if they had the same range, it would be expected that they would have the similar levels of persistent toxins.

It is not only local sources of toxins that affect killer whales. Persistent toxins accumulate in cold countries like Canada by evaporating and condensing again and again (this is known as global distillation). It has been proven that it only takes 5 to 10 days for toxins to come from as far away as Japan into British Columbia's waters.

Source: Dr. Peter Ross' research

Persistent chemicals in the food chain

How can it be that we allow these chemicals to go into the environment and build up in the food chain? We made mistakes in the past with chemicals like the pesticide DDT and PCBs. People thought these were “super chemicals”, great inventions that solved problems (DDT kills mosquitoes; it was used to kill bugs that might be carrying disease. PCBs conduct electricity, insulate, don’t burn and don’t corrode; they were used in everything from electrical lights to paint and printing ink.) These “super chemicals” were not tested for their long-term effects before they were put to use.

Look at the diagram to see how chemicals like PCBs move into and through the food chain.

The table below shows more of these persistent toxins. These are known as the “Dirty Dozen”. Notice that 9 of these 12 toxins are pesticides!

Persistent Organic Pollutant (POP)	Pesticide	Industrial Chemical	By-product
Aldrin
Chlordane
DDT
Dieldrin
Endrin
Heptachlor
Mirex
Toxaphene
Hexachlorobenzene
PCBs
Dioxins
Furans

After years of using these chemicals, animals in the food chain started having problems. For example, with DDT, the shells of large birds were too weak so that they would be crushed by the weight of the adults. Then the chemicals were tested and it was discovered that they bioaccumulate.

So we learned our lesson right?

No. We have definitely not learned our lesson. 

• Many countries still use the chemicals that have been proven to bioaccumulate
• These chemicals are stored all over the world and are often not properly disposed of
• Canada and America do not have laws that insist on the testing of new chemicals that are not used in food. (Source: Chemical Trespass)
• Of 300,000+ chemicals used in N. America, about 400 are “emerging chemical contaminants” (ECC) and can bioaccumulate. 75% have not been studied. (Source: Derek Muir, Environment Canada, Feb 2008)
• There is a new group of chemicals that are being produced in North America that has already proven to bioaccumulate. These are the PBDEs, a group of chemicals that are of use to humans because they don’t burn. They also are fire retardants just like PCBs were. There are at least 15 alternatives to their use that do not bioaccumulate. Europe has banned most PBDEs. North America has not

The "PBDEs" are a group of fire-retardant chemicals that contain the chemical bromine and stop fires. They have been proven to be persistent organic pollutants and are found in furniture, televisions and computers. PBDE = polybrominated diphenyl ethers

Persistent toxins and British Columbia's killer whales

Dr. Peter Ross studied the amount of toxins in the blubber of British Columbia's resident and transient killer whales. The blubber samples were used for both DNA and toxin research. The samples were collected by using a retractable dart system that removed a sample the size of a pencil eraser. Dr. Ross' studies are summarized in the chart below; the units of measurement are parts per million (ppm).

Questions

1. Use the "PCBs in British Columbia's Killer Whales" graph to fill in the following table:

Use the graph and the table to answer the following questions.

2. Researchers found that beluga whales in the St. Lawrence River had PCB loads of about 79 ppm. These animals had malformed skeletons and cancers and their population was severely endangered (Source: Muir et al). In ringed seals, a level of 77 ppm causes reproductive problems (Source: Oceana). Which killer whale populations are above these levels?

3. A level of 16.5 ppm causes immune system problems in harbour seals (Source: Oceana). Which killer whale populations are above this level?

4. A level above 50 ppm, is considered toxic waste by Canadian guidelines (Source: Oceana). Which killer whale populations are above this level?

5. In Canada, the action level for PCBs is 2 ppm. This is the amount that is too high for humans to eat food with this level of PCBs. Which killer whale populations are above this level?

6. Approximately how many times greater is the level of PCBs in Northern resident males than Northern resident females of reproductive age? Why do you think the males might have so many more toxins like PCBs?

7. Knowing what you do now about toxins in killer whales, explain why males might live much shorter lives.

8. Approximately how many times greater is the level of PCBs in Southern resident males than Northern resident males? Why do you think the southern residents might have so many more toxins like PCBs?

9. Summary: For each topic, mark the one that is most likely to have more toxins

Lesson 4: Evaluation/assessment tools

Answer key

1. Use the graph to fill in the following table:

2. Researchers found that beluga whales in the St. Lawrence River had PCB loads of about 79 ppm.

These animals had malformed skeletons and cancers and their population was severely endangered (Source: Muir et al). In ringed seals, a level of 77 ppm causes reproductive problems (Source: Oceana).

Which killer whale populations are above these levels?

Southern resident male and transient male

3. A level of 16.5 ppm causes immune system problems in harbour seals (Source: Oceana). Which killer whale populations are above this level?

Northern resident male, southern resident male and transient male

4. A level above 50 ppm, is considered toxic waste by Canadian guidelines (Source: Oceana). Which killer whale populations are above this level?

Southern resident male and transient male

5. In Canada, the action level for PCBs is 2 ppm. This is the amount that is too high for humans to eat food with this level of PCBs. Which killer whale populations are above this level?

All

6. Approximately how many times greater is the level of PCBs in Northern resident males than Northern resident females of reproductive age? Why do you think the males might have so many more toxins like PCBs?

Approximately 12 times greater (37/3). Females of reproductive age download toxins to their calves through the fatty mother’s milk and through the placenta. Males have no way of getting rid of the toxins.

7. Knowing what you do now about toxins in killer whales, explain why males might live much shorter lives.

Males may live shorter lives because they have far more toxins. [Where reproductive age females download the chemicals to their offspring via milk and the placenta]

8. Approximately how many times greater is the level of PCBs in Southern resident males than Northern resident males? Why do you think the southern residents might have so many more toxins like PCBs?

Approximately 4 times greater. They are more often in areas with more people meaning more pollution. Puget Sound specifically has high local toxin loads but toxins do come from around the world too.

9. Summary: For each topic, mark the one that is most likely to have more toxins

Lesson 5: Ready, set, action! Solutions for killer whales

Activity description

1. "What I have learned from killer whales". Guide a class discussion on what the bioaccumulation of toxins in killer whales is teaching us and what can be do to improve the situation. Click here for a summary
2. "I can make a difference!" My contract with mother Earth”. Students reflect on their own lives and think of ten specific ways that they can make changes to reduce chemicals in the food chain. Output can be in the form of a poem, drawing, poster, essay or journal entry
3. Have students write a letter or sign a petition to voice their concern about PBDE's. Letters can be directed to the member of parliament and/or Ministers of Environment, Health, or Industry . Contact links are at http://www.earthlingenterprises.ca/earthlingenterprises/Write_a_letter___petitions.html
4. Undertake further action to help the whales. Suggestions below. It is vitally important that students be able to apply what they have learned in order to enforce that their actions can make a difference. See teacher background information for helpful links
   • Students report back on their successes and difficulties in acting on their ten points in activity 2
   • Undertake a class campaign to adopt a killer whale http://www.killerwhale.org/ (Pacific northeast transients and northern residents) or http://www.whale-museum.org/ (southern residents)
   • Initiate an improved recycling programme for the school
   • Identify an environmental problem at the school and solve it e.g. reduce the use of disposable items by having people bring their own plates etc. to events; design and produce a school cup, school shopping bag, etc; reduce the amount of paper that is used; start using recycled paper; recycle batteries; have a campaign to reduce school electricity use; etc. 
   • Set up a school environmental club (see The Young Natualist Club of of British Columbia's school programme)

Lesson 5: Evaluation/assessment tools

Answer key

Solutions to reducing the chemical load in the environment

The intent is to emphasize individual empowerment and celebrate human intelligence. All living things do need to use the Earth’s resources but every little positive change helps.