Question

Where is light penetration in a river or stream likely to be lowest?
a.
the source
b.
the mouth
c.
the middle portion
d.
none of the above


Please select the best answer from the choices provided

A
B
C
D

Answer 1

A — the source. Headwater streams are typically narrow and shaded by riparian vegetation, so light penetration (and in-stream primary production) is lowest there.