Bioaccumulation in EcosystemsBioaccumulation in Ecosystems Amphibians are valuable Amphibians are valuable indicatorsindicators of environmental of environmental

health because they’re sensitive to chemical changes.health because they’re sensitive to chemical changes. Since the 80s the world amphibian population has Since the 80s the world amphibian population has

declined & birth deformities have increased.declined & birth deformities have increased. This may be due to: drought, increased UV rays, This may be due to: drought, increased UV rays,

pollution, habitat loss, parasites & diseases.pollution, habitat loss, parasites & diseases.

Amphibians, like this frog, have exhibited drastic changes since the 1980s.

BioaccumulationBioaccumulation BioaccumulationBioaccumulation: a slow build up of chemicals in : a slow build up of chemicals in

the bodies of organisms.the bodies of organisms. If bioaccumulation occurs in a If bioaccumulation occurs in a keystone specieskeystone species, ,

it can affect every other organism it can affect every other organism in its far reaching in its far reaching nichesniches..

Eg. bioaccumulation of PCBs in the Eg. bioaccumulation of PCBs in the B.C. Orcas.B.C. Orcas.

PCBs will affect the reproductive PCBs will affect the reproductive cycles of Orcas until at least 2030, cycles of Orcas until at least 2030, even though they were banned in ‘77.even though they were banned in ‘77.

Chemicals like Chemicals like PCBsPCBs and and DDTDDT & other insecticides & other insecticides are called are called persistent organic pollutants (POPs).persistent organic pollutants (POPs). POPsPOPs contain contain carboncarbon, & remain in water & soil , & remain in water & soil

for many years (like all organic comp)for many years (like all organic comp) DDTDDT, even at low levels (5 , even at low levels (5 ppmppm) causes nervous,) causes nervous,

immune & reproductive system disorders in immune & reproductive system disorders in animals.animals.

ppm ppm = parts per million= parts per million

Spraying DDT, 1958

Heavy metalsHeavy metals also also bioaccumulatebioaccumulate.. Lead, cadmium & mercury are the most dangerous.Lead, cadmium & mercury are the most dangerous.

•Lead Lead is not considered safe at any level, it can is not considered safe at any level, it can cause anemia, nervous & reproductive system cause anemia, nervous & reproductive system damage.damage.

•CadmiumCadmium is toxic to earthworms & causes many is toxic to earthworms & causes many health problems in fish.health problems in fish.

•CadmiumCadmium causes lung diseases, causes lung diseases, cancer, nervous & immune cancer, nervous & immune system damage in humans system damage in humans (exposure to cigarette smoke).(exposure to cigarette smoke).

MercuryMercury enters ecosystems through burning enters ecosystems through burning of fossil fuels, of fossil fuels, waste incineration, mining & the waste incineration, mining & the manufacture of batteries.manufacture of batteries.

Coal burning adds 40% of the mercury Coal burning adds 40% of the mercury released.released. Mercury Mercury bioaccumulates bioaccumulates in the brain, in the brain, heart & kidneys of heart & kidneys of many animals (Fish many animals (Fish bioaccumulatebioaccumulate mercury, adding risk mercury, adding risk for for any organisms eating fish).any organisms eating fish).

Reducing the effects of chemical pollutionReducing the effects of chemical pollution If chemicals are trapped in the soil, they If chemicals are trapped in the soil, they cannot enter the cannot enter the food chainsfood chains as easily. as easily. Bioremediation: Bioremediation: micro-organisms or plants micro-organisms or plants are used to help clean up, and are then are used to help clean up, and are then removed from the ecosystem.removed from the ecosystem.Eg. The oil industry will often use bacteria Eg. The oil industry will often use bacteria to “eat” oil spills.to “eat” oil spills.

BiomagnificationBiomagnification

Biomagnification:Biomagnification: the consumers in each the consumers in each trophic leveltrophic level receive larger doses of accumulated chemicals than receive larger doses of accumulated chemicals than the one before it.the one before it.

See page 94

The bioaccumulation of PCBs begins with the absorption of the chemicals by

microscopic plants and algae.

Overcoming the Problem…Overcoming the Problem… To overcome the problem biodegradable To overcome the problem biodegradable

pesticides should be used so they aren’t pesticides should be used so they aren’t stored in the tissues of organismsstored in the tissues of organisms