These are recommended for investigations into photosynthesis using algal balls. This is to help a pupil with an investigation comparing their rates of photosynthesis in different colours and intensities of light.
Debbie Eldridge comments:-
Of Chlorella and Scenedesmus they are both described as 'littoral' algae and as they are small floating organisms I imagine they exist in the same sort of habitats. I looked up Selanastrum and it is also described as littoral although I know no more than that.
If the pupil was comparing a single species rate at different wavelengths of light they may be able to relate this to living underwater.... different wavelengths absorbed differently etc. However, if they were trying to compare one species with another it would be very difficult with algal balls as they would have to make sure there was exactly the same amount of the different species in each.
Sue Hunt suggests:-
Speak to Sciento on 0161 773 6338 They are a mine of knowledge.
Barry Meatyard points out:-
The thing that controls the distribution of most algal species is the quality of the water - specifically its nutrient status.
The whole area of what was/is referred to as 'chromatic adaptation' in the algae (e.g. that red seaweeds are found in deeper water due to different spectral penetration) is a difficult one that is riven with exceptions and contradictory evidence.