1. One problem with solving the nutrient pollution problem is that much of the nitrogen and phosphorus entering our water bodies is from non-point sources. This means that there is no particular point at which we can try to control the source of the pollution. When it rains, nitrogen and phosphorus run off of farm fields and into streams, rivers, and lakes. Since these are non-point sources, how can we try to control these pollution sources?

2. Some species are known as "keystone species" in their ecosystems. Many other species and elements of the ecosystem are dependent on the keystone species. The removal of this species has more widespread effects on the ecosystem than the removal of other species would have. There may be some species whose role in the ecosystem is not key. Perhaps the ecosystem would adapt to the absence of that species. However, some of the connections between species are not apparent to us until the species is gone. Once the species has gone extinct, the effects on the ecosystem could be far greater than we had anticipated. What are the keystone species in your ecosystem? What are they? Are they in danger?