Sept 28, 2007, Delaware Valley Friends School 7th Grade Science Class will visit Bryn Mawr College 4 Fridays over the academic 2007 - 2008 year. They will Investigate aquatic ecology--make field environmental observations; sample the macroinvertebrate fauna at Mill Creekand Rhoads pond sites on the BMC campus; examine samples under the microscope in the lab, and use GPS to map sample site locations; overlay their data on an aerial map of the study area. The students will use a blogging site set up by Wil Franklin (Senior Biology Lab Instructor) to provide life history information on an organism they found.

To read the definitions of an ecosystem, ecology, watershed, macroinvertebrates, and about leaf pack experiments click here.

Activities and Schedule for Sept. 28, 2007

In the lab:

1)Brief discussion of watersheds and impacts to local water quality.

2) Brief introduction to aquatic fauna (insects, crustaceans, worms) and how they can be used to evaluate water quality conditions.

3) Description of how “leaf packs” provide a standardized sampling method, why that is important, and how we will make our own leaf packs for this project.

Preparing, Sampling, Identification, Mapping, Deploying Leaf Packs

  • Mappping sites using Google Maps.

  • Set up monitoring equipment and make Leaf Packs.

  • Discuss Benthic Sampling Protocol for Pond and Stream

  • Teams of students will be divided up along the different responsibilities required.

    • students will be Data Collectors and Deploy Leaf Packs.

    • students will Map the Sites and collect GPS Data.

    • students will be Macro-invertebrate Samplers.

    • Students will visit Rhoads Pond and Mill Creek to map the sites, gather site data and deploy leaf packs.

Field work outside:

1) Using GPS to map the sample site locations.

2) Measuring water quality parameters (temperature, dissolved oxygen content) at each sampling site. Observing other field characteristics of each sample site, e.g., amount of tree shade/sun exposure, water flow rate, water depth, sediment texture (muddy or gravelly).

3) Anchoring leaf packs and recording location and bag number.

4) Collecting net-drag samples of pond sediment; collecting kick samples in stream. Samples placed in buckets for macroinvertebrate identification back in the lab.

Back in the lab:

Identify, Discuss, Photograph Benthic Macro-invertebrate

1) Comparison of recorded water temperatures and oxygen levels from the sites.

2) Viewing GPS data overlain on air photo--sample sites in relation to each other and within watershed; where we walked to/from the lab.

3) Microscope work: identifying and counting macroinvertebrate fauna collected at each site.

4) Evaluation of Water Quality from Biotic Index? System, derived from Macroinvertebrate fauna counts. Visit Stroud Water Research Center for a description.

5) View Digital Photos of Macroinvertebrates sampled by Delaware Valley Friends School seventh grade science class on September 28, 2008 from Rhoads Pond and Mill Creek, Bryn Mawr, Pennsylvania.


Benthic Sampling Protocol

Aquatic insects are adapted to avoiding predation in their environment. As a result, if we want to catch aquatic insects, we need to minimize disturbance to their micro-habitat prior to sampling. This means we students should approach stream sampling sites from downstream and avoid tromping in sampling areas. Sampling streams with a D-net requires two people working together. Transferring samples from net into zip-lock bags also works best with two people.

Protocol --Stream sampling

1. Approach the sampling site from downstream, minimizing splashing.

2. Take any depth measurement you might need at sample site.

3. Label ziplock bag with site identifying information.

4. Person 1: Place D-net on stream bed with opening facing upstream and net firmly pressing into stream bottom. Tilt net slightly back to permit access of net opening by person 2.

5. Person 2: Disturb rocks in front of the net to dislodge stream insects and encourage flow of dislodged insects into the net. Steam insects have evolved to hanging on to substrate in fast moving water. For small streams like Mill Creek the best way to do this is:

• Use your hand or a rock to disturb the stream bottom in front of the net opening.

• Swirl water towards the net opening

• Pick up the surface layer of rocks in square area in front of the net opening for a distance upstream approx. equivalent to width of net.

• One by one scrub the surface of each rock with your hands to dislodge clinging insect larvae.

• Set aside each rock after scrubbing.

• Disturb sediment in lower rock layer, swirl water/bugs into net.

• Scoop net upwards so as it prevent insects from escaping.

• Invert contents of net into ziplock bag (preferably over a bucket or sieve/tray). Check net to make sure there are no stragglers.

• Add enough water to cover contents of sample (so that they survive the trip back to the lab)

Protocol --Pond sampling

1. Minimize splashing/disturbing the sampling site.

2. Take any depth measurement you might need at sample site.

3. Label ziplock bag with site identifying information.

4 Use D-net to scoop across the pond bottom, removing an area of sediment equivalent to width of net base squared. The majority of larvae we are interested in capturing will occur in the top layer of sediment so try to capture the top inch of sediment as you scoop.

5. Move the net to buckets of pond water and rinse contents by dipping the net bag into the water. MAKE SURE TO KEEP NET OPENING ABOVE WATER WHILE YOU DO THIS.

? Try to rinse as much of the fine sediment from the net as possible, this will make sorting in the lab easier.

6. Invert contents of net into ziplock bag (preferably over a bucket or sieve/tray). Check the net to make sure there are no stragglers.

7. If your gallon ziplock is less than 1/3 full of sediment you should scoop more. More than 1⁄2 full is probably overdoing it.

8. Add enough water to cover contents of sample (so that they survive the trip back to the lab)

Note: Both stream and pond samples ziplocks should be placed in buckets, transported back to lab and kept cool, preferably refrigerated until after-lunch viewing.

The activities, schedule and protocol were developed by Wil Franklin (Senior Lab Instructor at BMC)



Mapping Assignment

Using the information below can you find Rhoads Pond and Mill Creek?

Exercise #1.

1. Open a web browser and go to

2. In the lower left corner, you'll see "Place Name Search." In this box, type "Bryn Mawr College" and select "PA" for state, then click "Search."

3. When the next page appears, you'll see a prompt at the top of the page telling you to click on the Place name link. Click on "Bryn Mawr College."

4. On the next page, you'll see an image of a map that is "zoomed in" on Bryn Mawr College. On the lefthand side, change the map size from "small" to "large" so you can see more of the area surrounding Bryn Mawr.

5. Locate Mill Creek.

6. Using the scale selection drop box ("View scale") and the arrows that point left, right, up, and down, trace the path of Mill Creek to the ocean.

Consider these Questions:

1. How far do you think an organism we find at Bryn Mawr College would go along this path?

2. What other bodies of water might it encounter along the way?

3. Would it pass landmarks that you recognize?

4. Where do you think it would end up?

Exercise #2:

1. After you have completed this activity, go to

2. On top of the map of the United States, click "Satellite."

3. Again, search for Bryn Mawr College and click on the first entry.

4. See if you can repeat the activity above using the satelite images.

Consider these Questions:

1. What differences do you find between using the satelite images and using the topographic maps?

2. How do humans impact/interact with watersheds?

This mapping lab was developed by Kailin Friedman (06) a BMC Geology/ES undergradute student



Aerial Map of Rhoads Pond at Bryn Mawr College

Image Provided by Dr. D.Barber Geology Dept. BMC.

Ecosystem: An ecosystem is a natural system consisting of all plants, animals and microorganisms (biotic factors) in an area functioning together with all the non-living physical (abiotic) factors of the environment. (wikipedia encyclopedia)
Ecology: Is the scientific study of the distribution and abundance of living organisms and how the distribution and abundance are affected by interactions between the organisms and their environment. The environment of an organism includes both physical properties, which can be described as the sum of local abiotic factors such as insolation (sunlight), climate, and geology, and biotic factors, which are other organisms that share its habitat. (wikipedia encyclopedia)
Watershed: The area of land that drains into streams, lakes, estuaries or other bodies of water are known as watersheds. They are also known as drainage basins or catchments. As precipitation falls to the ground, the water is pulled downhill by gravity, which causes it to flow over the landscape or infiltrate through the soil into the groundwater. Topography - the hills, valleys, and other features that define the landscape - determine the boundaries of watersheds.

Every stream, regardless of its size, has a watershed. Smaller watersheds are contained within larger watersheds. For example, the French Creek watershed in southeastern Pennsylvania is part of the Schuylkill watershed, which in turn is part of the Delaware River Watershed, which is part of the Delaware Bay watershed. No matter where you live, you live within a watershed. Just as you have a home and school address, you also have a watershed address. Get to know your watershed address. (Stroud Water Research Center.

Animated Video of a watershed: Approx. 40 sec long Please give it a moment to load. (Note: video clip from the Conservation Technology Information Center website)
Macroinvertebrates: The groups of animals found in leaf packs are collectively called benthic macroinvertebrates or "macros" for short. Benthic refers to the bottom, in this case the bottom of a stream. Macroinvertebrates are animals without a backbone that can be seen with the naked eye. These bottom-dwelling animals include crustaceans and worms but most are aquatic insects. Beetles, caddisflies, stoneflies, mayflies, hellgrammites, dragonflies, true flies, and some moths are among the groups of insects represented in streams. Macros are an important link in the food web between the producers (leaves, algae) and higher consumers such as fish.
Leaf Pack: Please read "Interview with a scientist Dr. Bernard Sweeney" for a complete understanding of the use of leaf packs in studing stream ecology. You will leave the Bryn Mawr College Website when you click on the above link.

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