Determing the health of an acquatic ecosystem by identifying macroinvertebrates

1. Students will be able to define what macroinvertebrates are
2. Students will be able to use a dichotomous key to identify macroinvertebrates
3. Students will identify the health of an aquatic ecosystem using random samples
Students will learn how to analyze data using field techniques inside the classroom. They will learn how to further use a microscope and how to complete a professional data chart. A key concept that they will learn is that pollution of Earth's freshwater supply threatens habitat and health. Vocabulary words: Macroinvertebrates, biomagnification, pollution tolerant and intolerant species

This activity can be use for junior high or high school students and can be adapted for the field or just lab work. Bringing in samples alreay collected saves the time of taking students to the site. Using prepared preserved samples gives a little more control of findings. This is a lab exercise that should take 2-3 days in a typical class setting. Day one is used for identification using the dichotomous key and day two is used for counting and completing the pollution tolerance chart. Day 3 is optional if students need more time, or to have students present their findings to the class and hold a discussion. Students should be able to look at specimes under a microscope and be able to classify organisms into groups. This can be adapted to an environmental science class and made longer by spending time collecting the samples and preserving the samples prior to analyzing them. Samples can also come from local streams or wetlands.

Materials:
1. Dichotomous key of macroinvertebrates
2. Macroinvertebrates handout
3. Random samples of macros collected from various wetlands around area
4. Ecosystem handout
5. Petri dish
6. Tweezers
7. Pan
8. Microscope

Anticipatory Set:

Students will begin exploring what macroinvertebrates look like. They will look at them under a microscope and practice looking at different structures. Review with class how structures is related to function and try to come up with some common structures and extrapolate what their function would be as a class. Introduce terms: macroinvertebrate, pollution tolerance index, biomagnification and larva.

Procedure:

Day 1-

1. Students will already be introduced to dichotomous keys in previous lessons.
2. Students will be introduced to macroinvertebrates describing their structure and function. Basic facts such as where they are found, what makes them macro and invertebrates will be given along with any needed definitions.
3. The importance of macroinvertebrates will be discussed and related to aquatic ecosystems and their health.
4. Teacher will model how to identify structures of a macroinvertebrate and use the dichotomous key.
5. As a class, we will all choose the same macroinvertebrate and look for the same structures to aid in identification.

Day 2-

1. Groups of 3-4: indentifying macroinvertebrates
1. Students will get handout along with dichotomous key or website.
2. Students will use the information to fill in handout
2. After basic identification is complete, students will get a random sample of macroinvertebrates.
3. Students will separate out macros into groups of corixids, beetles, etc. and get a count to record on ecosystem handout.
4. After all the macros are identified and counted students will complete ecosystem handout to determine if they have a healthy ecosystem or not.

Day 3-

1. Students will finish filling out handout on health of ecosystem.
2. Students will present 1 macroinvertebrate that they found interesting to the class along with the results of their ecosystem health.
3. Class discussion on results of activity. What determines a healthy ecosystem? Why is it important? What measures can we take to ensure the ecosystems are health?

Have students be careful with samples as they are easily destroyed with repeated touching and handling. Wash hands after use. Students may need help with identification and verification of counts when completing the chart

1. Students will be able to use the dichotomous key to identify basic macroinvertebrates
2. Students should explain why their ecosystem is healthy or not using prior knowledge learned along with ecosystem handout.

3. Group grading of presentation along with discussion of findings.

Interdependence of life: The student will describe how the environment and interactions between organisms can affect the number of species and the diversity of species in an ecosystem.
Diversity of Organisms: The student will classify, compare and contrast the diversity of organisms on Earth and their modes of accommodating the requirements for life