Fridays in the Lab
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October 6, 2006

Water Quality and Stream Ecology

Senior Lab Instructor Wil Franklin, BMC Student Kaitlin Friedman, Dr. D. Barber

Pre-Visit Watershed Activity. 

Developed by Bryn Mawr College Geology/Environmental Science Major

Kaitlin Friedman


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.

        Email Questions (Comment on only one):

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


2. How do humans impact/interact with watersheds?


Student Responses to Pre-visit Question:
"How do humans impact/interact with watersheds?"

The following list of responses to the above quesion come from 17 Delaware Valley Friends School

11th graders, Paoli, PA. They are participating in a Bryn Mawr College program called Fridays in the

Lab sponsored by Howard Hughes Medical Institute. This program brings selected high school science

classes such as Delaware Valley Friends School to the campus on four Fridays during the academic year

for interactive laboratory demonstrations and short experiments.

These responses were part of a pre-visit assignment designed to introduce an aqautic monitoring study of

Rhoads Pond and Mill Creek.

1. We can prevent trees from being killed and plant more trees and if we
plant enogh they will suck up enough water to impact how much water is
left in the sheds and if it continutes all the water can be sucked in to
the trees cause the rain cant fill the water shed qicuk enough

2. Humans impact watersheds by pollution that people put in the water.

3. Humans impact and interact with watersheds because of polution and

4. Humans impact watersheds by the way they treat their environment. Such as
trash blowing into the watershed, cars gas pollute the watershed.

5. humans impact the streem by puting drainadge lines into it and runoff from
the roads and poulute the streem with waste and runoff from farms and
lawns they interact with it by swiming in it or fishing in it


6. Humans impact / interact with water sheads by do in activities such as: fishing, boating and
swimming in a lake. Humans also can impact a watershead and not know it
like when they drive past a river on a rainy day and a drop of oil falls
out of the car into a stream that goes into a lake witch will make the
fish sick.

7. Humans imapact and interact with watershed in many ways. Humans pollute
the water by using moter boats. Animals waist gets washed into the water
after it rains. Chemicals get washed into the rivers every day. We effect
is by every day activities. Driving, building houses, throwing away trash,
putting things on our lawns to make the grass go out to keep bugs out.
thax for listing to what i think!

8. Humans impact/ interact with watersheds. For starters they pollute the
water by leaving waste in the environment. They interact with the water by
boating and swimming in it. Chemicals get into water frequently because of
human's carelessness. This is not good.

9. Humans interact with the watersheads in may ways, Some good some bad. The
good things that we do are, we clean the water and test it to make sure
that its ssfe for animals and humans. we also dumpthings such as trash,
oil and pooh. Having a farm, or building a new house could affect it to. A
farm house cows and animals. The cows and outher animal waist washes into
hte ground and into the stream. Other things affect the water sheads as
well just like acid rain, this can make the water to acidic, or to base
affecting the about of oxyging in the water which can creat fish kills. So
theres many things that we do that affect the water sheads and as befoer
some are good soame bad. ide just like to think that someday we can afect
the water sheads in a positive way.

10. Humans interact and impact with watersheds in many different ways. I
remember the first time i ever went to the watershed, i went in about
fourth grade with my elementary school, it was the Wissahickon Water Shed.
I know the many boats and trash are put into waters esp. at water sheds.
Many chemicals get washed into the water after rain falls. Other things
such as driving, building, trash, and simple things as just urinating.

11. Humans intercat and with the watersheds in many different ways some in
good ways and in negative ways.

12. First off  we are always effecting the water with our chemicals used on
our lawn and faields to kill bugs and pests but usualy those chemicals
find there way into the grownd and edventialy into the water effectivly
polluteing the water and killing the animals and organisms the live  in

But humans also interect wiht the watersheds in indestructive ways  usualy
in recreation  such as fishing  boating and swimming
this way both the organisms can coenside togethor.

13. Humans impact and interact with watersheds by polluteing the water around
the city and in all different places. When people throw their trash into
the water they pollute the water and mess it up Sometimes the rain
pollutes the water when it rains the dirt turns into mud and the mud goes
into the water and makes it all muddy.

14. I thinc that wen animels and humins have wast we inpac the woter shed

15. Humans have both good and bad impacts and interactions with water sheds.
In the schuykill, many people boat and fish. boating does not have a
negitive effect, unless powerboats are used which pump gasoline into the
water. Fishing is not harmful unless the area is overfished, in which case
the ecosystem can be hurt. One bad interaction people have is that they
throw trash into the river, which kills wildlife and makes it look ugly.

16. Humans interact with watersheds by fishing, boating, and crew running.
Humans impact it by dumping thier oil down the sewer drain, throwing trash
in the river and not caring for Mother Earth at all period.

17. Humans have impacted water sheds a lot over time by throwing chemicals,
human waste and trash into water ways for years without ever thinking of
the impact it will have. Despite trying to clean out some of these water
ways, many are still too poluted for animals to live in or drink from. I
remember my parents telling me when they were kids that they would go and
swim in the local lake or stream. Now swimming in natural bodies of water
is discouraged because there are usually bits of rusty metal, broken
glass, trash or chemicals in them, which no one wants their children
swimming in. Unfortunatly, most people don't care about how they are
poluting the air and water ways and that soon the O-zone layer will be so
thin that you won't be able to leave the house without sunscreen, so i
don't know when all of this is going to be taken care of and it will be
safe to drink from natural streams again.

Delawary Valley Friends (DVF) Students

Activities and Schedule:

by Wil Franklin (Senior Lab Instructor at Bryn Mawr College)

Benthic Macro-invertebrate Sampling and Identification

  • Set up monitoring equipment and take initial “vital signs” of Rhoads Pond and Mill Creek.
  • Teams of 6 students will be divided up along the different responsibilities required.
    • 2 students will be Data Collectors and deploy Leaf Packs.
    • 2 students will map the sites and collect GIS data.
    • 2 students will be Macro-invertebrate Samplers.
  • Teams will visit either Phoads Pond or Mill Creek, complete the initial sampling, map the site, deploy Leaf Packs, and gather site data.


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 ½ full is probably overdoing it.

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

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


Click here for DVF Students Post-Visit Assignment


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