2. Terrestrial leaf litter is an important nutrient source in streams

3. Leaf Decomposition 1) Leaves become waterlogged and sink. May lose up to 42% mass to leaching. 1) Leaves become waterlogged and sink. May lose up to 42% mass to leaching. 2) Colonization by bacteria and fungi begins almost immediately.

4. 3) Colonized by shredders (eat CPOM). Shredders convert CPOM to FPOM. Grazers eat algae and diatoms (FPOM). Leaf Decomposition Water penny Crayfish Crane fly Amphipod Snail Diatoms

5. 4) Collector-gatherers (eat FPOM). 4) Collector-gatherers (eat FPOM). 5) Collector-filterers (eat FPOM). Bacteria and fungi continue to break down CPOM and FPOM. 5) Collector-filterers (eat FPOM). Bacteria and fungi continue to break down CPOM and FPOM. Leaf Decomposition Mayfly Caddisfly Midge Black fly

6. Predators eat other invertebrates Damselfly Dragonfly Hellgrammite

7. Purpose of this lab Question 1: Does presence of macroinvertebrates accelerate leaf decomposition? Question 1: Does presence of macroinvertebrates accelerate leaf decomposition?

8. Purpose of this lab Question 2: Do leaves containing more carbon degrade more slowly? Question 2: Do leaves containing more carbon degrade more slowly? Cellulose and lignin are resistant to decomposition. Cellulose and lignin are resistant to decomposition.

9. Methods Prepare coarse-mesh maple, coarse-mesh oak, fine- mesh maple, and fine-mesh oak bags. Prepare coarse-mesh maple, coarse-mesh oak, fine- mesh maple, and fine-mesh oak bags. Place and secure bags in stream/pond. Place and secure bags in stream/pond. Remove bags after ~1 month. Remove bags after ~1 month. Rinse macroinvertebrates from leaves and allow leaves to dry. Rinse macroinvertebrates from leaves and allow leaves to dry. Weigh and estimate leaf material lost. Weigh and estimate leaf material lost. Count macroinvertebrates and sort according to functional feeding groups. Count macroinvertebrates and sort according to functional feeding groups.

10. Black fly (Collector-filterer)