1. Environmental changes that impact ecosystem stability

2. Algal Bloom Harmful algal blooms can:
Produce extremely dangerous toxins that can sicken or kill
people and animals
Create dead zones in the water
Raise treatment costs for drinking water
Hurt industries that depend on clean water

3. Deforestation
Deforestation can have a negative impact on the environment. The most dramatic impact is a loss of habitat for millions of species.
Eighty percent of Earth's land animals and plants live in forests, and many cannot survive the deforestation that destroys their homes. Deforestation also drives climate change.

4. Desertification
Desertification is the process by which fertile land is transformed into desert as it becomes progressively drier and unable to support any plant growth for food production.
Desertification is having major impact in many places on our planet today, and is expected to affect humanity even more in the future as we experience an increase in human population, and as our planet faces scarcity of natural resources such as clean water.

5. Overfishing
Overfishing is a form of overexploitation where fish stocks are reduced to below acceptable levels.
Overfishing can occur in water bodies of any sizes, such as ponds, rivers, lakes or oceans, and can result in resource depletion, reduced biological growth rates and low biomass levels.

6. Oil Spills
Oil spills frequently kill marine mammals such as whales, dolphins, seals and sea otters. Oil also coats the fur of otters and seals, leaving them vulnerable to hypothermia.
Even when marine mammals escape the immediate effects, an oil spill can cause damage by contaminating their food supply.

7. Greenhouse Effects
Carbon dioxide (CO2) and other greenhouse gases act like a blanket, absorbing IR radiation and preventing it from escaping into outer space. The net effect is the gradual heating of Earth's atmosphere and surface, a process known as global warming.
Too many greenhouse gases can cause the temperature to increase out of control.

8. Climate Change
Sea levels are rising and oceans are becoming warmer. Longer, more intense droughts threaten crops, wildlife and freshwater supplies.
From polar bears in the Arctic to marine turtles off the coast of Africa, our planet's diversity of life is at risk from the changing climate.

9. Invasive Species
An invasive species can be any kind of living organism—an amphibian (like the cane toad), plant, insect, fish, fungus, bacteria, or even an organism's seeds or eggs—that is not native to an ecosystem and causes harm. They can harm the environment, the economy, or even human health.

10. Invasive Species Cont
Invasive species can have a number of negative impacts on the areas that they invade. Perhaps the most significant of these is the widespread loss of habitat. 
Some invaders can physically alter the habitat in addition to destruction.
Other invasive species may not destroy habitat but can have an impact by killing large numbers of endemic species.