How Humans Affect Sustainability Ecology Ms. McGrath

Definitions Pesticide: kills pests Insecticide: kills insects Herbicide: kills plants

Review…. Trophic Levels Trophic Level is a category of organisms defined by how they get energy: Primary producers (plants) Primary consumers (herbivores) Secondary consumers (carnivores) Tertiary consumers (top carnivores)

Bioaccumulation Bioaccumulation toxins are ingested by an organism at a rate greater than they are eliminated. These toxins build up in the tissues of the organisms

Biomagnification Biomagnification the increase in the concentration of a toxin as it moves from one trophic level to the next. Greatest health problems at top of food chain. Ex: Plankton  squid  fish  dolphins Dolphins would have a greater concentration of toxins than plankton

Biomagnification

Example grass  mice  fox  wolf  bear Each wolf eats hundreds of foxes Each fox eats thousands of mice Each mice eats pounds of grass Therefore the bear ingests billions of doses of chemicals/toxins.

Example grass  mice  fox  wolf  bear The grass starts with 2 units of toxins. The mice eats 100lbs of grass ◦ 200 units of toxins The fox eats 1000 mice ◦ 200,000 units of toxins The wolf eats 100 foxes ◦ 20,000,000 units of toxins

Which organisms would have the highest concentration of DDT?

Check Your Understanding… What is the relationship between the trophic level of an organism and the concentration of DDT in its body? In your own words, explain why animals at the top of a food chain are particularly at risk from poisons in the environment.

Page 309 Pollution in the North Pollutants applied in fields, often in warmer climates & other pollutants in air (from burning fuel) evaporate (water cycle) to the atmosphere ◦ Return in rain, carried back up, return in rain ◦ Travel north towards the Arctic from wind currents Cold locks them in – few plants, poor soil, less sunlight so these pollutants are not broken down ◦ Enter food chains = bioaccumulation, then biomagnification ◦ Breast milk toxins 9x higher in Inuit women ◦ Animal abnormalities (seals without hair, etc.)