Which type of stream has limited macrophyte presence due to turbid conditions?

High order streams are characterized by their larger size and increased water volume, often resulting in higher velocities and turbulence. These conditions can lead to turbid water, where sediment and other particulates are suspended in the water column. The turbidity in high order streams limits the amount of sunlight that can penetrate the surface, which is essential for photosynthesis in macrophytes (aquatic plants).

In turbid conditions, the growth of macrophytes is inhibited since they rely on light for their biological processes. As a result, high order streams typically exhibit limited presence of these plants compared to streams with clearer water. In contrast, low order streams and middle streams generally have lower flow velocities and can support more stable ecological conditions, allowing for a greater variety of aquatic vegetation. Alluvial streams, which are formed from sediments deposited by flowing water, can also vary in turbidity but often have sections where light penetration is sufficiently high to support macrophyte growth.