Tenth lecture

Human effects on ecological balance Example 1 Hawks are natural enemies for mice, rats & rabbits. If they were eliminated; mice, rats & rabbits would increase in number and ruin the crops.

Example 2 Pumas, wolves &coyotes prey on deer. One year, a drive killed these enemies. Deer multiplied in numbers. They didn’t have enough food. Many of them died from starvation. The others chewed the bark of the trees; the trees died; the small mammals and birds lost shelter and food. Human effects on ecological balance

Example 3 Mongoose was introduced to Jamaica to control rats. Mongoose also killed birds, snakes & lizards. The cane beetles multiplied & do much damage as rats.

Human effects on ecological balance Example 4 In 1862, a few pairs of rabbits were introduced to Australia. Within a few decades; there were millions of rabbits. They destroyed grassland and crops. In 1950; A deadly virus, myxomatosis, was introduced to control rabbits.

Human effects on ecological balance Example 5 In 1916, Japanese beetle, spread rapidly in New Jersey and soon were responsible for loss of millions of dollars’ worth of fruit, crops, lawns and flowers.

Air pollution Is the contamination of the air by noxious gases and minute particles of solid and liquid matter (particulates) in concentrations that endanger health Air pollution only occurs outdoors

Sources of Outside Air Pollution Combustion of gasoline and other hydrocarbon fuels in cars, trucks, and airplanes Burning of fossil fuels (oil, coal, and dinosaur bones) Insecticides Herbicides Everyday radioactive fallouts Dust from fertilizers Mining operations Livestock feedlots

Sources of Indoor pollution Efficient insulation Bacteria Molds and mildews Viruses animal dander and cat saliva plants house dust Mites Cockroaches pollen

Effects on the environment Acid rain Ozone depletion Global warming In human population- respiratory problems, allergies, strengthens lugs, and a risk for cancer

What’s in smog? particulates (especially lead) nitrous oxides potassium Carbon monoxide Other toxic chemicals

Acid rain contains high levels of sulfuric or nitric acids contaminate drinking water and vegetation damage aquatic life erode buildings Alters the chemical equilibrium of some soils

Reflected Light Re-radiated Heat CO 2 HEAT! Trapped Heat Cloud, Dust Greenhouse effect 13