1. Leaf Decomposition in Aquatic Ecosystems

2. Terrestrial leaf litter is an important nutrient source in aquatic eccosystems

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

4. Leaf Decomposition con’t
3) Colonized by shredders (eat CPOM). Shredders convert CPOM to FPOM. Grazers eat algae and diatoms (FPOM).
Crane
fly
Crayfish
Amphipod
Snail
Water penny
Diatoms

5. Leaf Decomposition con’t
4) Collector-gatherers (eat FPOM).
5) Collector-filterers (eat FPOM).
Bacteria and fungi continue to break down CPOM and FPOM.
Mayfly
Midge
Black fly
Caddisfly

6. Predators eat other invertebrates
Hellgrammite
Dragonfly
Damselfly

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

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

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

10. (Collector-filterer)
Black fly
(Collector-filterer)