Algae

[EKoepf1173]

All other things being equal (especially light intensity) if you change
the angle of 
incidence of light from 90 degrees (straight down) to more oblique angles
more
and more light will be reflected, instead of passed through the water. 
This results in a lower light intensity.  This will probably reduce the
growth rate of the algae, unless the light intensity of the 90 degree
light is too intense and causes photoinhibition, in which case a reduction
in light intensity will increase
photosynthesis and growth rate.

Eric Koepfler
Associate Professor
Marine Science Department
Coastal Carolina University