Question

1. Explain the problem of zebra mussels, and invasive species (see Case Study 11.1 in Natural Resource Conservation). Describe their spread in North America. Explain the environmental and economic problems associated with zebra mussels. What are some methods that are being used to control them?

2. Identify a pathogen that has a significant impact on human health. What are its health effects? How is it spread? How might climate change or increased global connectivity (such as international travel) affect the spread of the pathogen? Explain how pathogens might be used in bioterrorism.

3. Describe two problems facing marine fisheries. Choose three regulations or economic incentives and explain how they could foster sustainable marine fisheries?

4. Explain the costs and benefits of clear-cutting versus selective cutting when harvesting trees. How does integrated pest management help improve forest health? How do controlled burns and the "Let It Burn" policy contribute to forest health and sustainable forestry?

Answer 1

Zebra mussel is previously native to Europe and Western Europe. But they were introduced into North America unintentionally. They become invasive species in North America and cause various problem. The problem caused by Zebra mussel are:

I. They cause the death of other species of native freshwater species.

II. Zebra mussel outcompete native mussel and other invertebrates.

Environmental and economic problem that are associated with zenra mussel are:

I. The zebra mussel affect the water quality.

II. It bring problem like clog water.

III. They disturb the ecological food web.

IV. They cause damge to the boats.

Some methods to bring them in control are:

I. Regular inspection of boat and trailer.

II. Regular draining of water from the boats where these mussels grow.

III. Wash boat with disinfectant and other agents.

There are many pathogen that are not good for human health and cause diseases in human. For example, virus, bacteria, fungi and protozoa. But the maximum harm caused to human health is virus. It is the parasite that is totally dependent on human body. Derive the nutrients and complete their life cycle . But cause severe diseases. For example, virus cause HIV , that is one of the deadly disease.