Answer:
Dead leaves
Step-by-step explanation:
Small streams that remain shaded in any area (due to dense canopy) are unable to get sufficient light and hence they depend for their energy on other resources.
Usually, a shady stream is found in a temperate environment, where interlocked canopies block the path of sun light. However, ample amount of leaves (as food base) are supplied to these streams. Biological communities in these shady streams feed upon the leaves and release fine organic particle and oxygen with in the stream thereby making it oxygenated and cool.