Draw a food chain of some animals you might see around your home.

Agenda for Tuesday Dec 21st 1.Bioaccumulation2.Video3.Species relationships

About DDT

• DDT is a pesticide used for mosquito control and pest control

• DDT accumulation in some bird species resulted in death, nervous system damage, and reproductive failure

• DDT was banned in the United States in 1972

What kind of damage can DDT cause to birds?

• In the body of an animal, DDT is changed (metabolized) to DDE.

• DDE dissolves in fat, not in water, and is stored in fatty tissues. – DDE tends to remain in the body and can

cause several problems

DDE: Kinds of Damage

• Reproductive failure (in birds- eggshell thinning)

• Immune system problems

• Nervous system damage

• Death

How does DDT move into lakes, streams and oceans?

• After DDT is applied, – Some volatizes– Some remains on the plant– Some washes off into the soil

• eventually going into a stream, river, or lake

• DDT on leaves of plants:– ingested by primary consumers (insects and rodents)

• DDT in water:– remain in the sediment – consumed by bottom-feeding organisms – absorbed by fish gills and skin.

Is DDT still used today?YES

• Insect control on crops

• Used for mosquito control

Food Web

ORGANIC DEBRIS

Osprey

Water Plants

Sucker

Bay Shrimp

Trout

Plankton

Silverside

Food Chain

ORGANIC DEBRIS

Osprey

Large Mouth Bass

Crayfish

Why is food web knowledge important for understanding the impact of DDT on ospreys and

eagles?

Ospreys and eagles are tertiary consumers and this makes them particularly vulnerable

to DDT because of

andbioaccumulation biomagnification

• Bioaccumulation = the accumulation of a contaminant or toxin in or on an organism from all sources (e.g., food, water, air)– accumulate in living things and stored faster

than they are broken down (metabolized) or excreted

Biomagnification = the increase in concentration of toxin as it passes through

successive levels of the food web

DDE accumulates at higher levels in organisms that are higher in the food chain

Biomagnification of a DDE in Aquatic Environment

Tertiary Consumer 3-76 µg/g ww

(fish eating birds)

Level Amount of DDE in Tissue

Secondary Consumers 1-2 µg/g ww

(large fish)

Primary Consumers

(small fish)0.2-1.2 µg/g ww

Primary Producers

(algae and aquatic plants)

0.04 µg/g ww

Considering biomagnification, how could DDE harm an osprey?

Osprey Food Web

Large Mouth Bass

Crayfish

Plant material and algae

3-76 µg/g ww

1-2 µg/g ww

0.2- 1.2 µg/g ww

0.04 µg/g ww

DDE Concentration

Osprey

The Effects of DDE on Reproduction

Species Effect on Reproduction

DDE: Critical Concentration (measured in egg contents)

Bald Eagle None < 3µg/g 1

Bald Eagle Failure 16 µg/g 1

Osprey Failure 17.6 µg/g 2

1. Wiemeyer, S.N. et al., 1984. Organochlorine pesticide, polychlorobiphenyl, and mercury residues in bald eagles, 1969-1979, and their relationship to shell thinning and reproduction. Arch. Environ. Contam. Toxicol., 13, 529.

2. Johnson, D.R. et al., 1975. DDT and PCB levels in Lake Coeur d’Alene, Idaho osprey eggs, Bull. Environ. Contam. Toxicol., 13, 401.

Effects of DDE

• High levels of DDE cause the female ospreys to lay eggs with thin eggshells.– Thin eggshells have a greater chance of

breaking, leading to embryo death.

• With high levels of DDE, female ospreys can also lay eggs that contain high enough concentration of DDE to prevent embryo development.

Calculating amounts of DDT/DDE

• Suppose an osprey eats 200g of fish per day. The fish tissue consumed by the osprey has an average DDE concentration of 0.1μg/g. How much DDE is the osprey consuming in one day?

• (200g fish/day)(0.1 μg DDE/g fish) = 20 μg DDE/day