[APD] Re: algae/plant competition and uptake rates

[Clint Brearley <clint_brearley at telstra_com>]

Oxygen can be very toxic for all living things. It readily breaks down to form oxygen radicals which are very unstable and damaging. To deal with this, we have two enzymes, superoxide dismutase (SOD) and peroxidase which quickly breakdown the radicals into water (via peroxide). We have these enzymes, plants have these enzymes and I expect that algae would have these enzymes also.

However, the efficiency of these enzymes can vary from species-to-species depending on environmental conditions. I know of certain bacteria that are inhibited by high dissolved oxygen levels. Perhaps this is the case for algae as well?

This could be tested by setting up a tank with light/nutrients/CO2 and no plants (perhaps plastic plants) and monitoring and controlling DOT levels by injecting pure oxygen gas. Might be an interesting experiment for anyone with the right equipment who is so inclined.

Clint Brearley
Melbourne, Australia

> One factor I never see discussed here is oxygen levels. Any time 
> it is
> brought up, someone usually says elevated oxygen has not shown to 
> play a
> significant role in reducing alga in the aquarium, and yet if you 
> search the
> internet you can find references in many government studies, USDA, 
> Wildlifemanagement, university studies, for water management of 
> lakes and ponds
> where low oxygen levels promote extreme alga infestations. Are you 
> lookingat stagnant swamp water in Florida, or free flowing water?
> 
> Would a low oxygen substrate stunt plant growth? Would elevating 
> the oxygen
> level in the water column slow algae growth in combination with 
> lower temps?
> 
> Robert Paul Hudson
> www.aquabotanic.com


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