Fridays in the Lab
Nov 16, 2007

Ecology of Rhoads Pond
and Mill Creek


Blog & Photographs Organisms

Return to First Visit Sept 28th, 2007

Second visit: Nov 16, 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.

In the lab:

1) Discussion of physical and chemical characteristics of the pond and stream bottom habitat, why these vary from place to place, and how these characteristics influence aquatic organisms.

2) Description of how we quantitatively measure bottom characteristics, e.g., relative amounts of mud, sand and gravel; oxygen levels in the sediment; and amount of organic detritus (leaves).

Outside field work:

1) Measure and record water temperature and oxygen levels at each sampling site; qualitative observations of other site characteristics such as water clarity/turbidity, seasonal change in shade levels and sunlight amounts. Brief discussion of how/why these differences arise.

2) Collection of pond and stream bottom sediment samples for lab analysis.

3) Retrieval of leaf packs from each sample location.

Back in the lab:

1) Wet-sieve analysis of stream and pond sediment samples; separation of the gravel, sand and mud fractions to be dried then weighed. Create and view a histogram plot of these sediment texture results.

2) Observation and mineralogical identification of sand and gravel particles under the microscope.

3) Identification and counting of macroinvertebrate fauna collected in leaf pack samples.

4) Evaluation of Water Quality from Biotic Index? System from the leaf pack sample results. Visit Stroud Water Research Center ( for a description.

5) Wrap-up discussion.

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