In this activity developed by NOAA, students model estuaries, artificially enriching both fresh and salt water samples with different amounts of nutrients and observing the growth of algae over a several weeks. They relate their results to the phenomenon of algae blooms in estuaries. They then analyze data for different sites at the Guana Tolomato Matanzas National Estuarine Research Reserve (GTMNERR) in Florida to discover the relationships between nitrogen, chlorophyll, and dissolved oxygen. Finally, they study how nutrients cycle through an estuary and suggest recommendations for reducing nutrient inputs to estuary waters.
Students will be able to:
- Understand how water quality and nutrient parameters in an estuary can indicate disruptions to ecological processes in estuaries.
- Interpret data from an experiment to explain the effects of over-enrichment on water quality and living things; and relate this lab experience to the phenomenon of algae blooms and eutrophication in an estuary.
- Explain the phenomena of algae blooms and eutrophication in terms of total nitrogen, chlorophyll-a, and dissolved oxygen.
- Describe the effects of eutrophication on the nitrogen cycle.
- Explain how nutrients cycle in an estuary and how natural processes and human impacts affect this cycle.
- Identify sources of nitrogen inputs to estuaries and identify some ways to limit them.
CONTEXT FOR USE
- 1 (55 minute) class session, plus periodic observations every 2-3 days over three weeks (Part 1)
- 3 (55 minute) class sessions (Parts 2 and 3)
Organization of the Activity: This activity consists of 3 parts which help deepen understanding of estuarine systems:
- Nutrients in an Estuary
- Using Data to Study Eutrophication and Conditions in an Estuary
- Eutrophication and the Nitrogen Cycle
- As possible, plan the scheduling of the parts of this activity. You may want to begin Part 1 of this activity two to three weeks before you begin Parts 2 and 3.
- Assemble materials (See material list included).
- Contact the landowner and ask for permission before you collect the water samples you will need for this exercise. Collect pond and/or estuary water samples that include algae. The amount of water you will need depends on how many samples students will treat or control. If estuary water is not available, use pond, stream, puddle, or tap water samples.
- Determine where in your classroom student groups will place their experiment so that all the beakers will get the same amount of sunlight or ambient light. (Note: If you decide to have students design their own experiments, you can allow them to determine if light is a variable they will change.)
- Optional: Set up different sets of beakers yourself and label them prominently. (Note: Ideally students prepare the beakers themselves.)
- If necessary, download Google Earth and install it on your classroom computer(s) or computer lab machines <http://earth.google.com/>. Preset the location of the GTMNERR.
- Bookmark this eutrophication animation to use during Part 3 of the activity.
- Make copies of the Student Reading—Introduction to GTM, Student Reading—Nutrients in an Estuary, Student Worksheet—Nutrients in an Estuary, and Student Data Sheet—GTM 2002-3 Nutrient Data.