Aquatic
Ecosystems

5th grade fall unit

revised October 2, 2007

   

Unit goals

We are surrounded by lakes, stream, marshes, ponds, and other aquatic ecosystems, each of which are affected by, and thus a reflection of, our society's activities as well as the plants and animals that live there. Furthermore, the conditions of our waters in turn impacts our lives in a number of ways. In this unit the students will recognize these interactions by studying River Bend's wetlands, making an assessment of their current conditions, and then gathering further information to gauge various impacts that can cause change over time.

This unit is specifically designed to address appropriate AAAS Project 2061 benchmarks as well as fifth grade Minnesota Academic Science Standards Ia, Ib, IVe, and IVf. E-mail here for more information.
 

-- Summary Box --

Before your visit, please review with your students ...

  • Basic principles of scientific investigation
  • The aquatic habitats that can be found in our area 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

At River Bend ... (a worksheet will be used - download)

  • During the introduction we will review the above material
  • Students will be divided into teams, about 4-5 students per team, but no more than six groups per classroom.
  • Progress through various tests and activities to closely examine one of two different aquatic habitats at River Bend, the Prairie Pond or the Turtle Pond.
    • Vegetation survey
    • Animal survey
    • Insect survey
    • Weather conditions
    • Water properties
      • temperature
      • depth
    • Water chemistry (download indicator sheet)
      • Phosphates
      • Nitrates
      • Dissolved oxygen
      • pH
    • Chart, map, and discuss results
  • In the closing we will ...
    • inquire about students' results and provide local perspective
    • review some societal choice involved in maintaining healthy aquatic habitats
    • remind the students of their next visit
    • talk of upcoming events at River Bend
    • invite the students to return on their own with family and friends

Back in the classroom ...

  • Diagram the wetlands at River Bend using the data collected. The book One Small Square: Pond has a good example.
  • Monitor results from other classes and from previous years (as available here)
  • Research aquatic habitat stewardship issues

(trouble downloading? click here)
 

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 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 effect were 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 differents 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 imortant 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 "macro-organisms (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 - and body of water that lasts for a few days or more may attract aquatic life

What other types of aquatic systems can be found on Earth?

Feel free to research any of these they don't seem familiar:

  • lake
  • ocean
  • creek
  • lagoon
  • bog
  • sea
  • glacier
  • tidal pool
  • geyser
  • fen
  • flood plain
  • bog
  • estuary
  • aquifer
  • salt lake

What will we do at River Bend?

You and your team will visit one of River Bend's ponds and complete a series of tests and observations -- sort of a "snapshot" assessment of that aquatic ecosystem. Eventually you will compare your results to those of other teams and in future years teams will make comparisons to yours.

You and your team will: (download worksheet)

  • Record date and the weather conditions at the time of your visit.
  • Draw a sky view map of the pond, including living and dead vegetation, various structures and visible features, and wildlife sighted at that time.
  • Test the various physical properties of the pond:
    • What are the deepest and shallowest water depths?
    • What are the warmest and coldest temperatures of the water?
  • Perform several experiments to tell you more about the chemical properties of the water (detailed indicator sheet ):
    • Dissolved oxygen: Primarily absorbed from the air but also created by plants and used by animals. Also consumed by the decomposition of organic matter.
    • Nitrates: Excessive nitrogen from animal waste and fertilizers boosts plant growth
    • Phosphates: Excessive phosphorus from our detergents creates algae blooms that lead to other water quality problems
    • pH: A measure of how acidic or basic the water is. The pH is affected by geology of the area, plant growth, and pollutants. Water that is too acidic or too basic will cause a variety of problems for aquatic species.
  • Collect and identify insects and other creatures in and around the pond. They often are indicators of water quality as some insect prefer "dirty" water and others "clean" water. Download detailed indicator sheet.

Your data will be compiled with data gathered by other teams to generate ranges and averages for future comparisons.

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.
  • 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 question than doing just one test.

What do we need to remember when we visit River Bend?

  1. The quieter we are, the better.
  2. Listen to your leader.
  3. Be careful and safe with all tools and equipment
  4. Raise your hand if you have something to say.
  5. Do not pick anything unless given permission.
  6. Stay where you leader asks you to be.
  7. Be respectful of nature - and of each other!

2007 data reports

Prairie Pond Data - 2007
Date
Sept. 25
Linc/Jeff
Sept. 26
Jeff/DMCS
Sept. 27
Linc/Roos
Sept. 28
Roos

Oct.29
Nerst.
2007
Averages
   2006 Data
2005 Data
 
a.m.
p.m.
a.m.
p.m.
a.m.
p.m.
a.m.
p.m.
 a.m. p.m.
(for week)
     
Air
Temp (F)
69.3
69.3
43
61.5
52.3
n/a
n/a
62.9
   n/a
59.7
48.8
62.5

Water
Temp (F)

58.1
60.8
50
60.3
54.1
n/a
n/a
58.6
   n/a
57
46.2
57.4

Water
Depth
4.4
4.4
5.1
5.4
6.7
n/a
n/a
4
   n/a
5
12.19
19.3
pH
Test
6.1
6.4
6.3
6.2
6.1
n/a
n/a
7.1
   n/a
6.4
6.27
7.7
Phosphate
Test
2.2
2.5
2.7
2.8
1.4
n/a
n/a
1.1
   n/a
2.1
0.42
1.14
Nitrate
Test
1.8
1.2
0.8
1.3
1
n/a
n/a
1.4
   n/a
1.3
0.98
1.3
D. Oxygen Test
3.6
6
5.5
8.2
4.7
n/a
n/a
8.8
   n/a
6.1
6.29
8.4
 
Turtle Pond Data - 2007
Date
Sept. 25
Linc/Roos.
Sept. 26
Jeff/FLS
Sept. 27
Linc/Roos
Sept. 28
DMCS
Oct. 29
Nerst.
2007
Averages
   2006 Data
2005
Data
 
a.m.
p.m.
a.m.
p.m.
a.m.
p.m.
p.m.
p.m.
 a.m. p.m.
(for week)
    
Air
Temp (F)
69.3
69.3
43
61.5
52.3
n/a
n/a
62.9
   n/a
59.72
42.87
62.5

Water
Temp (F)

57.5
60.4
52.8
61.8
54.3
n/a
n/a
64.4
   n/a
58.53
40.13
57.74

Water
Depth

28.2
30.5
28.7
23.5
29.8
n/a
n/a
26.2
   n/a
27.82
32.25
34.41
pH
Test
6
6.3
6.2
6.6
6.8
n/a
n/a
6.7
   n/a
6.43
6.32
7.02
Phosphate
Test
0.2
0.4
0.4
0
0.2
n/a
n/a
0.6
   n/a
0.30
0.39
1.14
Nitrate
Test
0.7
1.5
1.2
2
1.3
n/a
n/a
1.2
   n/a
1.32
0.96
0.72
D. Oxygen Test
1.3
2.3
2
3.4
2.2
n/a
n/a
2
   n/a
2.20
2.17
4.13
 

 

Photos of some past classes!

Taken by teachers and RBNC staff (click to enlarge)

 
Do you have more photos? Send in your best!

 

Some suggested pre- or post-visit activities

Send us your ideas here!

  • Create model pond ecosystem (such as DSMII Pond Life) including a chart showing similarities and differences of River Bend's wetlands.
  • 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.

(trouble downloading? click here)

Interesting links

The following links contain some interesting information on aquatic ecosystems: Send us your ideas (and broken links) here!

Here is a site that talks about pond chemistry:
http://www.vcnet.com/koi_net/H2Oquality.html

Ideas for related projects:
http://www.wavcc.org/wvc/cadre/WaterQuality/water_quality_testing.htm

   

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Faribault MN USA
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