Aquatic Ecosystem Study - A River Bend Nature Center Field Study

Transcription

1 Aquatic Ecosystem Study - A River Bend Nature Center Field Study Grade Level: 5th Length of Lessons: Intro: min Who Dirtied the Water: 15 min Field Stations: 80 min (approx min at each station) Conclusion: 25 minutes Objectives: Students will: 1. Identify the components of the aquatic ecosystem and how they interact. 2. Identify factors that impact the health of an aquatic ecosystem and how to test for them. 3. Collect data and make observations that will be shared with other students and the public via the RBNC website. 4. Explain how the aquatic ecosystem is impacted by human activities. Minnesota Academic Science Standards Identify and collect relevant evidence, make systematic observations and accurate measurements, and identify variables in a scientific investigation Natural systems have many components that interact to maintain the living system. AAAS Project 2061 Benchmarks Core Knowledge Sequence for Science N/A Materials Intro computer, projector, T-tube, laser thermometer, DO test materials Who Dirtied the Water x2 aquariums, film canisters filled with correct materials, script AquaEco Survey Filter Materials: Clear plastic cups, Coffee filters, Cotton balls, Gravel, Sand, Sponge pieces, Straws, Paper cups; 2 duffel bags (one for each site) containing: Turbidity Tube, Laser Thermometer, x2 Dissolved Oxygen Kits, ph Strips, Waste Bucket, Tape Measure, Egg Timer, x6 Dip Nets, x2white Bins, Ice Cube Tray, x2 Plastic Spoons, Colored Pencils, x2 Goggles, Instruction/critter sheets, Extra bucket for water; student worksheets & clipboards Conclusion computer, projector, water from Who Dirtied the Water Location Intro/Who Dirtied the Water/Conclusion Trailside classroom Aquatic Survey outdoor classroom, ponds (Turtle, Hidden, Prairie, or Spring depending on the amount of water at sites) Background Information What is an aquatic ecosystem? Aquatic systems are those that contain plants and animals that predominantly depend on a significant amount of water to be present for at least part of the year. But a perfect definition is tough to make. How many weeks a year does an area need to show standing water in order to be a pond? How about a bird bath or dog water dish, as both can breed aquatic insects if left undisturbed for a few days? For our

2 purposes, we have a number of aquatic systems that hold water all year (in most cases) and are impacted to different degrees by activities on the surrounding landscape. What are a few components of an aquatic ecosystem? - pond layers - Like in a forest, the top, middle, and bottom of a pond can be vastly different from each other, and even the layers in between. Under different temperature or light conditions the water in a pond can vary greatly in oxygen, clarity, and other factors that affect where plants and animals might live. The air above the pond and the land below the pond are important as well, as those provide space for animals to live, plants to root, and predators and prey to interact. - diversity - while many people think of a pond as just a small lake with frogs and fish, there are thousands of different species of plants and animals living together in a natural pond. The more diverse a pond is (more species that it has) the stronger and healthier it is. - micro-organisms - some of the most important plants and animals in a pond are so small they are difficult to see without a microscope. They are called "micro-organisms" (micro=small, organism=life form) and while a few may cause disease, almost all are very beneficial and important to a pond ecosystem. While bigger animals may fly, walk, or swim away to other ponds, micro-organisms are always present in large numbers. - macro-organisms - larger plants and animals that are easy to see on a pond are called "macroorganisms (macro=large). They are the plants and animals that we often notice first, and can more easily spread from pond to pond. What aquatic systems can be found at River Bend? Marsh - shallow water with non-woody plants growing above water level Swamp - like a marsh but with bushes and trees growing from the water as well Pond - a small and shallow body of water with plants growing above water level only on the edges; generally freezes solid during winter. River - a moving body of water that flows from one place to another. Stream - smaller than a river, may even dry up sometimes Puddles - any body of water that lasts for a few days or more may attract aquatic life Spring - area where underground water is discharged onto the land surface forming a pond or stream What other types of aquatic systems can be found on Earth? You may research any of these that don't seem familiar: lake ocean creek lagoon bog sea glacier tidal pool geyser fen flood plain bog estuary aquifer salt lake What are some basic principles of a scientific investigation? Science is often a process of performing scientific tests to investigate and learn things. For example, we can test a sample of water to see how much oxygen is present in a pond. In order for such tests to have any meaning, there are some rules (or "principles") that we must remember: Follow all directions and safety instructions for a test carefully. Do each test the same way each time you do it. Procedure: When measuring something, be as exact as possible. Doing the same test several times and taking an average can give you a better answer to a question than doing just one test. Site Set-up & Prep

3 Scout locations for the field study; if Prairie Pond is dry, decide if you are going to use the spring or Hidden Ponds as the second site. Gather program materials at Trailside. The day of the program, take the computer and projector down to TS and set it up to project the worksheet onto the white board. Separate materials into 2 kit bags. Load clipboards with student worksheets and pens. Prior to visiting River Bend (for teachers) Before your visit, please review with your students: Basic principles of scientific investigation The aquatic habitats that can be found in Minnesota and elsewhere The general types of tests and observations that we will be making during the visit Importance of dressing for the day's weather conditions Introduction Intro is at trailside. Students sit with groups (5-6 students) and with class (one class goes to each pond). Not more than 6-7 groups per pond/site. Introduce self and leaders Review studying prairie and forest from 4 th grade. This year in the fall you will be studying aquatic systems in more detail. What is an aquatic ecosystem? What types does RBNC have? Why would we study the ponds and other water habitats? (For animal health, to monitor problems, --) Where does RBNC water come from? Rain, runoff, underground springs Town and RBNC not separate places. It is continuous. Chemicals from town can get to RBNC water. Who Dirtied the Water? Now it is time to find out Who Dirtied the Water? This activity illustrates the cumulative impact that a community has on its water bodies. You need 10 volunteers who can read LOUDLY and well. Hand them their cards and canisters and explain to the whole group that each of the volunteers has a part and they need to listen to find out how they dirtied the water. See the script for details. Reflecting on Who Dirtied the Water? At the end ask- Would you want to play in this lake anymore? Who made the water dirty? Who didn t make it dirty? Is it easy to make choices to keep the water clean? Introduction (continued) Today each class will study one site and then we will compare the results. We will add your results to the data we have collected in the past. We are monitoring over time looking for trends and changes. Hand out clipboards w/ worksheet and direction page/aquatic animals laminated. Students write in Names, Climate data, Remember to read the directions!!!! AIR TEMP from IC Show students how to fill in worksheet test info by projecting the worksheet onto the whiteboard using the computer and projector. As you go down the worksheet, review tests they do (dissolved oxy, ph, depth, temp) and tools like thermometers, rulers for depth, waste bucket. Remind students how to take the laser temps and how to do a median. Show them the ph test strips, and where to compare the color. Go through the dissolved oxygen test: be sure to put on the goggles, put the ampule in the beaker, break the tip, remove it from the beaker & gently move it back & forth, remind students NOT to put their finger over the tip of the broken ampule, then compare it to the ones in the kit.

4 Also explain that besides the tests they will also be building a filter. A filter is a device (usually a membrane or layer) that is designed to physically block certain objects or substances while letting others through; use the example of a Brita filter at home. They are designing a filter to try and get the pollutants out of the water from Cannon Lake. They will be using items like cotton balls, sponges, gravel and sand, etc. to build it at the sites. Then they will take it back and during the conclusion we will see whose filter cleans the Who Dirtied the Water? water the best! Remind students to: Do one test at a time only one goes to water at a time Rotate to open test site Stay with group unless you are going to get the water sample Notice the garbage bin location Stay on docks/3-point rule/belly rule Explain that if they are waiting for a station to open up or finish all the tests and built their filter then they can ask a leader for a drawing sheet. There will be colored pencils to draw a scientific drawing of your site. This means that you should draw what your site looks like and include lots of details. Use the mural on the wall as an example. Discuss what things they see that might affect the water quality of the pond (animals, the road, trees, etc.) When they are at their site they should make observations about things that might affect the water quality in their pond. They don t have to be good artists but they need to be good observers! Aquatic Ecosystem Survey Station 1 Water properties: Use the laser thermometer to take 5 temp readings of the water surface and then find the median. Use the yard stick to take 5 measurements of the water depth and find the median. Write the median results onto the worksheet. Station 2 Turbidity: This station needs an adult helper; often times kids have trouble with getting the tube filled or with duckweed floating on the top. 1. Make sure clamp on drain tube is closed. 2. Submerge tube in water until full. 3. Remove tube from water, holding over pond. 4. Look into t-tube while unclamping drain tube and slowly let water out. 5. As soon as you can see the black & white disk at bottom of t-tube, close drain tube with clamp. 6. Read level of water left in t-tube using ruler on outside of tube (in centimeters). 7. Write result on worksheet; pour remaining water back into pond. Station 3 ph: 1. Get strip of ph paper from container 2. Hold one end, dip other directly in pond water or in the small jar 3. Wait 15 seconds 4. Compare to color chart for ph number 5. Write result on worksheet, place paper strip in waste jar Station 4 Dissolved Oxygen: 1. Fill small cup to 25 ml mark 2. Put on goggles 3. Put pointed end of glass tube into bottom of cup and snap off tip. (Pond water is automatically pulled into tube.) 4. Dump cup s remaining liquid into waste jar, return cup and goggles 5. Tip glass tube back a forth a few times to mix chemical and pond water 6. Wait 2 minutes, compare with other color tubes at station 7. Write result on worksheet, and then put entire glass tube into waste jar at station

5 Station 5 Dip-Netting: This station needs an adult helper. Use the standard 3 point/belly stance to dip into the water. Try to avoid getting just duckweed or muck from the bottom. Let most of the water drain out of the net before standing up & taking net to tub. It works well to use 2 dry tubs to have them dump their nets into and then direct students to use spoons to look for insects. If insects are found, sort them into the ice cube trays. After about 5-7 minutes have students return to the trail and fill in the bugs they found on their worksheet, using the critter quality sheet for comparison. Station 6 Build a Filter: Using the materials provided, work as a team to build a filter for the water from Cannon Lake. Each team will have: 1 paper cup, 1 coffee filter, 3 cotton balls, 2 straws, 1 sponge piece, gravel, and sand. Filters will be tested at the end of the lesson back in Trailside. Scientific Illustration: Students should observe their study site and draw the site and any details that they think might affect the water quality. They should include LOTS of details. They can draw things and label them if it isn t clear from the drawing. When they finish their drawing they should show it to a leader before they start the Word Find on the back of the page. They need to include at LEAST 10 details about their site. Conclusion Back inside, ask a few questions about what plants they saw, what animals, and so forth. What were their favorite things? Did they find anything that was rare? One of the adult leaders will gather data from all groups and enter it directly into the computer. This may take a few minutes. While the data is being put into the computer, another adult will facilitate testing their filters with our dirty Cannon Lake water. One group member should bring their filter to the front of the classroom. Then a leader can pour some water through everyone s filter and we can compare the results to an unfiltered sample from Cannon Lake and the other groups. Use applause to pick the winner. If there is time (usually there isn t), ask the student with the cleanest water what they used in their filter. Compare pond results what is the same/different? Review ppm and what tests mean. How do our measurements compare with the standards? (ph , DO of 5-6 ppm, turbidity 20 cm or above is good). Connect it all together by discussing similarities and differences between the groups results and the ponds. Turtle is deeper, less oxygen etc. Over all, what rating would they give RBNC s water quality? (Thumbs up, down, or middle) Thank students for being citizen scientists and helping us collect this important data. Encourage students to come back again and share what they have learned with others. Invite them back with their families to explore River Bend and remind them about upcoming events. Next spring they will be doing studying the woods and river valley. Remind students to leave the clipboards on the floor. They can take their worksheets and drawings with them. Direct students attention to their teachers for further instructions. Assessment N/A Extensions/Resources (for teachers) Diagram the wetlands at River Bend using the data collected. The book One Small Square: Pond has a good example. Create model pond ecosystem (such as DSMII Pond Life) including a chart showing similarities and differences of River Bend's wetlands.

6 References N/A Monitor the results from other classes posted on this site to include in graphing. (In the future, most value will be gained by comparing results from different years). Research other types of wetlands, in North America and around the globe. Monitor and research current news stories on phosphates, acid rain, and any other articles relating concerns regarding rivers, ponds, marshes, and other aquatic systems. The following links contain interesting information on aquatic ecosystems. o Pond chemistry: o Groundwater and drinking water: o Ideas for related projects: