- Slides: 22
Deadly Links: Day One You will be one of these animals in the activity: § Grasshopper – you only eat plants
§ Shrew – you eat grasshoppers
§ Hawk – you only eat shrews
Deadly Links: Day One 1. What animal were you? Grasshopper, shrew, or hawk 2. Were you eaten? Yes or no 3. What animal ate you? Shrew, hawk, or nobody Record the number of each color food pieces you have at the end of the game: Brown: _____ (If you got eaten, write 0. ) Green: _____ Yellow: _____ Total pieces of food you “ate”: _____
Deadly Links The story continues…
The Bad News… There is a pesticide in the environment. This pesticide was sprayed on the crops the grasshoppers were eating, in order to prevent a lot of damage by the grasshoppers.
Deadly Links: Day Two 1. What did the yellow food pieces represent?
Deadly Links: Day Two 1. What did the yellow food pieces represent? Yellow = pesticide
Why pesticide? Crop damage would result in: § the farmers having less of their crop to sell § people and animals not having as much food § higher costs, because of smaller quantity available
Characteristics of the pesticide: § poisonous § accumulates in food chains § stays in the environment for a long time
The Good News… Not all populations die from it. They are not all affected the same way.
2. How many pieces would your animal have had to eat before it died?
Grasshoppers Any pieces of pesticide-covered food (even just 1 single piece) = death
Shrews Half or more of your food supply contaminated (half or more of the total = death)
Hawks Don’t die from the pesticide, but one will not be able to reproduce. (The hawk with the highest number of pesticide pieces has so much accumulated in its body, that the egg shells will be too thin to hatch successfully. )
Your survival… 3. Which sentence describes your outcome? § I died because I was eaten. § I died because I ate too many yellow pieces. § I survived!
DDT § Insects were sprayed fish ate insects hawks, eagles, & pelicans ate fish § The poison became concentrated in the birds, sometimes weakening and killing them directly, and sometimes affecting their reproduction. § DDT is prohibited by law in the USA. § It has not been prohibited worldwide, and can sometimes still enter the food chain.
Fertilizers and Pesticides § Chemicals that are inorganic, synthesized compounds can have varying effects in the environment. § The pesticide might be sprayed or dusted on a crop. It might settle into the soil, or stay on the crop, until it is washed by rain or irrigation into water sources – groundwater, lakes, streams, oceans.
§ Testing the water doesn’t always show a high concentration of the chemicals, but testing the fish usually does. § Waterfowl and other species who eat the fish (including humans) can be affected. § Many of the chemicals do not pass out of their bodies, but accumulate over time.
Advantages & Disadvantages 4. What are some reasons for using pesticides, and what are some problems with using them? Advantages Disadvantages
5. What might happen if farmers didn’t use pesticides? 6. List the food chain from this activity, and tell how each link was affected by the pesticide. There were 4 links in this chain. 1 → 2 → 3 → 4