... however light intensity levels vary considerably along the stream due to trees and bushes which are quite dense in places, spaced well apart in other places and totally absent in other regions. Aim: The aim of my investigation is to see whether varying light intensity at a stream affects the species diversity. Light intensities will be recorded in specific zones and samples will be taken in the stream at the zones to see if a difference in light results in a change in species diversity. Background information: Rays of light falling on the surface of the water do not penetrate very far, and sedimentary matter, even organisms themselves, will absorb light. The most obvious effect of light is to promote the growth of the plants. The plants are mostly emergent plants so add little to the fresh water habitat and if anything maybe net removers of oxygen yet the plants ...

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