Bioaccumulation and Biomagnification

1. Bioaccumulation and Biomagnification Tracing Pollution Through An Ecosystem

2. Pests and Pesticides

3. 4 Types of Pesticides • Herbicides : kills plants • Insecticides : kills insects • Fungicides : kills fungi • Bactericides : kills bacteria

4. Pesticides • First generation pesticides • found to be toxic to humans • polluted water and soil • NOT biodegradable (able to break down naturally) • Second generation pesticides • generally man made organic chemicals • They were less toxic to humans • More biodegradable

5. Pesticides • some of these chemicals are fat soluble and become stored within animal tissues. • This creates a problem known as bioaccumulation.

6. Bioaccumulation • Toxins and poisons begin to build up in living organisms. • Toxins increase in concentration over time. • The substance is taken in (ingested, absorbed or inhaled) and stored faster than it is broken down by the body

7. Bioaccumulation Examples: • DDT (and other pesticides) • Methyl Mercury (and other industrial pollution) Effects: • Cancer and Birth Defects, • Changes in body chemistry

8. An example… DDT • Benefits • Low toxicity for humans • Highly effective against insects • Easy and cheap to manufacture • Problems • Remains active in the environment for a long time • Causes shell thinning in birds and other reproductive problems • Status • Banned for use in North America since the 1970’s • Still used in the 3rd World to fight malaria (carried by mosquitoes) • Saves 1000’s of human lives each year

9. Biomagnification • process that results in the build-up of a chemical in an organism at higher levels than are found in its prey. • occurs when a chemical becomes more and more concentrated as it moves up a food chain • Eating contaminated food “magnifies” the effect of bioaccumulation.

10. Biomagnification • Tracking through the use of colored dots: • Producers suffer from only bioaccumulation and receive one dot. • Consumers suffer from both bioaccumulation and biomagnification and receive an extra dot for each increase in trophic level.

11. In Lake Ontario… • mothers who consumed high amounts of Lake Ontario fish were found to have babies with poor reflexes and whose organs developed at a slower than normal level

12. YOUR TASK • DDT Case Study- Read Article and Answer questions