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Here's something about aquariums that I find very intriguing. Algae have been around on earth far longer than aquatic plants. They have a evolutionary head start . So how can a home aquarist win against algae? Are 100% algae free tanks impossible? Seems to me unless we physically remove every trace of algae from the tank (by sterlizling, boiling the water etc) they should exist in the tank and be just as happy as plants when it comes to uptaking nutrients. However, some types of algae may have evolved so that they harvest essentially macro nutrients from their inorganic compounds exclusively and other evolved to utilize organic compounds. So in a ecological system where spores of both forms exist, one would compete and replace the other depending on the available resources. But I dont understand how aquatic plants can outcompete algae for nutrients, it seems to me that algae have evolved far efficient processes, in fact the biomass of algae in waterbodies, I think, exceed that of plants.
I think grazing is the best defense against algae, in fact that is how algae populations are controlled in nature, stable water systems overrun with algae signal a change in the dynamics of the water body and an absense of predators. In such situations algae populations are limited by the algae themselves. Inherent competition among algae in a closed system like a aquarium cannot be negligible. Moreover, algae populations will grow to match the supply of nutrients, which is where uptake by plants come in. However, algae will survive and utilize nutrients in micro quantities, if they cant, they'll be replaced by those that have evolved to do so.
after this long rambling meaningless post, my question is what are your thoughts on how algae are limited in stable tanks? It seems almost impossible, given the diversity and tenacity of algae.
 

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Simple, algae (microphytes) and macrophytes are not in the same niche.
Assuming they are will get you into trouble.

Marine open ocean phytoplankton are quite different from Macrocytsis kelp.

If I am an alga spore, I do not need much nutrient supply, if I am a billion celled weed, I do.

The main way macrophytes beat algae is with light.

Algae do not continue to take up nutrients at the same rate, it levels off while plants keep taking in more and can store more at higher levels.

Sculthorpe
And Chambers and Lampert's textbook on Ecological Physiology are good.

Main folks doing research on submersed aquatic weeds are in FL and , Neatherlands and Demark.

Regards,
Tom Barr
 

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Excellent! I get to discuss things with Tom Barr!! Its an honour.

Algae do not continue to take up nutrients at the same rate, it levels off while plants keep taking in more and can store more at higher levels.
do algae levels also stabilize or level off, what I mean is while they may not individually take up nutrients exponentially, the logical strategy would be to increase their numbers to uptake nutrients. So in a race for nutrients in the home aquarium or any environment, the algae and the plants are essentially doing the same thing, one is taking up nutrients and storing them and the other is taking up nutrients and increasing its numbers.

Also what do you mean by macrophytes beating algae with light?

Also, I dont think I completely understand the whole process of algae thriving in tanks that are underdosed. If one particular species of algae does well with low levels of nutrients, they would not care if the water column is rich with nutrients or not, they would thrive regardless. But the fact is they only appear with nutrient deficiencies, which to me means that they are replacing populations of algae that would have done well with higher levels of nutrients. So are plants completely out of the equation here?
 

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baj said:
Excellent! I get to discuss things with Tom Barr!! Its an honour.

Algae do not continue to take up nutrients at the same rate, it levels off while plants keep taking in more and can store more at higher levels.
do algae levels also stabilize or level off, what I mean is while they may not individually take up nutrients exponentially, the logical strategy would be to increase their numbers to uptake nutrients. So in a race for nutrients in the home aquarium or any environment, the algae and the plants are essentially doing the same thing, one is taking up nutrients and storing them and the other is taking up nutrients and increasing its numbers.

Also what do you mean by macrophytes beating algae with light?

Also, I dont think I completely understand the whole process of algae thriving in tanks that are underdosed. If one particular species of algae does well with low levels of nutrients, they would not care if the water column is rich with nutrients or not, they would thrive regardless. But the fact is they only appear with nutrient deficiencies, which to me means that they are replacing populations of algae that would have done well with higher levels of nutrients. So are plants completely out of the equation here?
The algae are at a completely different scale than the Macrophytes.
Nutrient transport, the amounts need to maintain growth etc are all much different than for Macrophytes.

The plants would die or simply stop growing at all and just sit and wait till more nutrients are brought into the system. Plants will do one of these things.
Algae are not limited though. You don't have a test kit good enough(I don't and most researchers don't for that matter) to measure many of the nutrients to the point where they might become limiting to algae/periphyton.

At higher levels of nutrients, many species are geared to grow at certain low levels, and when the nutrients get richer, another algae(or plant) starts to fill this place. So the other low nutrient algae goes to spores and waits till things are ripe once again nutrient wise.

Some things trigger resting spore formation, some trigger bloom.

Think about it like seeds that grow at a certain time of year and only in a certain set of conditions. Temperature also plays a role.

Plants are far less picky and have a wider range.
Plants have a larger surface area and are able to process light better and shade out algae below where the spores are.

Regards,
Tom Barr
 
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