Engage: Ask: What are the implications of high levels of nutrients in an aquatic system? Based on their experience with previous lessons, they should be able to answer this question. Ask: Do you think the Hudson is eutrophic? How could you find out?
Explore: Students will use the accompanying reading and graphs to answer a variety of questions about the nutrient levels in the Hudson River.
Explain: The Hudson River has always had problems with pollution, but the focus has shifted in the last twenty years from toxic substances to the control of nutrient pollution and consequent eutrophication. More than sixty percent of coastal waters in the U.S. are moderately to severely degraded by nutrient pollution, most of which originates in the interior of the U.S. Eutrophication from excess nutrients leads to decreasing biodiversity, increasing frequency of algal blooms, and degradation of water quality due to reduced dissolved oxygen levels. In the Hudson River, primary productivity has increased dramatically since the 1970s, and is considered eutrophic.
Extend: Students could research connections with human health.
Evaluate: Collect student answers to the reading.