As signs of spring in Austin begin to emerge dotting the landscape with white, purple and red buds, a reminder of fall remains in our streams colored with orange, red and brown leaves. Those fallen leaves may be a vision of winter, but their role in the stream is critical during spring and summer months. Much of the food and energy within a stream system comes from non-living organic inputs from the land. When leaves fall from trees into streams, they travel downstream with the flow of the water and frequently get caught up behind rocks or on branches hanging in the water.
Once the leaves enter the water they begin to slowly break down and leach out nutrients used by aquatic organisms. Fungus and other microorganisms do their job of decomposing the leaf. When the leaves become softer, macroinvertebrates move in and begin to shred the course leaves into finer particles. These leaf packs are also safe moist places for the macroinvertebrates to live and find protection from predators.