Station 6: Pond Water Exploration

Lab Activity - Exploring Pond Diversity

Materials

• Pond water sample

• Beaker, sample bag, or small clear container

• Permanent marker (for labeling)

• Compound light microscope

• Glass slides (minimum 5–6)

• Coverslips

• Transfer pipettes

• Lens paper

• Paper towels or Kimwipes

• Identification key (provided)

• Phone or camera for photomicrography

Part I – Constructing Your Microecosystem

1. Gently swirl the source pond water to suspend organisms.

2. Transfer approximately 150–250 mL into a beaker, sample bag, or container.

3. Include:

   • A small amount of bottom sediment (recommended)

   • Visible algae or plant fragments if present

4. Leave air space at the top for oxygen exchange.

5. Label the container with group name and date.

6. Place the ecosystem in the designated lab area under ambient light (not direct sunlight).

Do not disturb the container except when sampling.

Part II – Sampling Protocol (Week 1)

You will examine 5 wet mounts.

Each wet mount must contain two drops of sample.
Total sampling effort = 10 drops.

How to Sample

Before each slide:

• Gently swirl the container once.

• Sample from different microhabitats:

  • Just above sediment

  • Near algae or plant material

  • Mid-water column

  • Surface layer

Avoid vigorous shaking.

Slide Preparation

1. Place two drops on a clean slide.

2. Lower the coverslip at an angle to minimize air bubbles.

3. Scan under 40× to locate organisms.

4. Observe under 100× and 400× for identification.

Examine each slide carefully before moving to the next.

Part III – Recording Diversity

Using the provided identification key:

1. Identify each distinct organism type observed.

2. Take at least one clear photo of each organism type.

3. Count total individuals across all 5 slides.

4. Assign an abundance category:

• Rare: 0–2 individuals total

• Uncommon: 3–10 individuals total

• Common: More than 10 individuals total

Record results in a data table including:

• Organism name

• Abundance category

• Trophic role (producer, consumer, decomposer)

Be systematic. Count cumulatively across all slides before assigning abundance.

Part IV – Week 2: Re-Examination

After one week:

1. Repeat the same 5-slide sampling protocol.

2. Use the same abundance criteria.

3. Record all organisms observed.

4. Compare Week 2 data to Week 1.