Algae are nutrient scavengers

[dw1305]

Hi all,
Thank again for the posts, I think they have added to this thread. Tom they are lovely photos, we have a lot of trout fishing "chalk streams" the Wylye, Salisbury Avon, Kennet etc locally, they are still clear, although abstraction and eutrophication has taken it's toll on the fishing. What is the plant with the accumulation of "marl" on its roots? it is not one I recognise. Seeing the marl reminds of the Burren in western Ireland, with its turloughs and marl lakes, here's Lough Bunny <http://static.panoramio.com/photos/original/11429692.jpg>, very clear, but not quite as warm.

I must admit I deliberately tried to leave high pH, highly buffered, carbonate saturated water (these are?) out of the equation, due to the extra level of variables thrown up by both the carbon dioxide >< carbonate >< bicarbonate equation and the conversion of orthophosphates to relatively insoluble calcium phosphate compounds, as well as the variable CEC of the sediments etc.

I agree that there is no argument that plant growth is enhanced by higher macro-nutrient, and particularly nitrogen levels. In fact for many plants its a linear growth response up to very high levels of nitrogen, I even co-authored a paper on the nitrogen response of plants for schools, using hydroponic radishes <http://www-saps.plantsci.cam.ac.uk/journals/ward.pdf>. The same with carbon, we do the "Cabomba" experiment ( http://www-saps.plantsci.cam.ac.uk/articles/cabomba/cabomba.htm earlier in the thread, using 1% sodium hydrogen carbonate solution as the carbon source), in classes and the increased oxygen evolution is quite startling.

I have seen "Dusko's Walstad tank" article, very impressive, I also like the EI thread and "James' Planted Tank - All In One Solution" <http://www.theplantedtank.co.uk/allinone.htm> and "Dosing with Ammonia and Urea" etc. They may not be what interests your standard aquarist, but they certainly interest me.

It probably is my ecological background, but If I was purely growing aquatic plants in an aquaria with the aim of growing the "best" plants, (and I'd agree that many of the plants illustrated couldn't be any better condition than they are), I would have no qualms about growing them with plenty of light, an added carbon source, ammonium nitrate as a nitrogen source etc., but personally I wouldn't do it in a planted aquaria with fish and/or inverts, and I couldn't advise any-one else to do it either.

I've probably said all that I can usefully say now, so I'll go back to "lurking", but I'm sure I will carry on enjoying the vast majority of posts.

cheers Darrel

 

[plantbrain]

Hi all,
Thank again for the posts, I think they have added to this thread. Tom they are lovely photos, we have a lot of trout fishing "chalk streams" the Wylye, Salisbury Avon, Kennet etc locally, they are still clear, although abstraction and eutrophication has taken it's toll on the fishing. What is the plant with the accumulation of "marl" on its roots? it is not one I recognise. Seeing the marl reminds of the Burren in western Ireland, with its turloughs and marl lakes, here's Lough Bunny <http://static.panoramio.com/photos/original/11429692.jpg>, very clear, but not quite as warm.

Marl= calcium and magnesium carbonates, they are declaifying the water to get DIC(or Carbon/CO2/ using HCO3 as a source). Common in hardwater plants.

I must admit I deliberately tried to leave high pH, highly buffered, carbonate saturated water (these are?) out of the equation, due to the extra level of variables thrown up by both the carbon dioxide >< carbonate >< bicarbonate equation and the conversion of orthophosphates to relatively insoluble calcium phosphate compounds, as well as the variable CEC of the sediments etc.

Then the plant is really CO2 limited, and must use Bicarb as a DIC source.
Vals, Egeria, Hydrilla etc are good at this, most of the 400 species we keep do not.
All plants prefer the gas CO2. Sometimes PO4 can be caught in the Ca/CO3 mix.

I agree that there is no argument that plant growth is enhanced by higher macro-nutrient, and particularly nitrogen levels. In fact for many plants its a linear growth response up to very high levels of nitrogen, I even co-authored a paper on the nitrogen response of plants for schools, using hydroponic radishes <http://www-saps.plantsci.cam.ac.uk/journals/ward.pdf>. The same with carbon, we do the "Cabomba" experiment ( http://www-saps.plantsci.cam.ac.uk/articles/cabomba/cabomba.htm earlier in the thread, using 1% sodium hydrogen carbonate solution as the carbon source), in classes and the increased oxygen evolution is quite startling.

You might use DIY CO2 from yeast and repeat the Cabomba test
You can measure the CO2 production at different temps of the yeast brew to show how yeast enzymes respond to temp changes. Then you can also test the plant response to elevated CO2[aq] and then compare that to HCO3 sources of DIC.

Now you have a pretty cool class room test of 3 things and can break the students up into groups to focus on each.
Or do them in stages and have them collect CO2 via inverted test tube in water to measure gas volume between treatments(say pH and temp over a range to get a bell shaped curve). Then the CO2 brew can be used along with Bicarb sources of DIC and you can measure the O2 production ins a sealed chamber over time with a rubber gasket for an O2 probe or take samples of the water and reseal.

Plenty of nice options for enzyme kinetics, even color spectrum use, DIC sources, allocation, temp effects, pH effects rates etc etc. Light intensity is also a good one and O2 production, electron transport chain can be measured even using a color metric blue solution and say spinach pulp/chloroplast. The blue color will be increases as more NADPH is available to reduce the blue indicator(clear= no reduction, blue= reduced).

A good paper on nutrients for aquatic plants is Gerloff's 1966 paper.
Old but good. EI dosing is about 1/5th of that Hoalgnad' modified version there. Which is about what the one of the authors suggested(Paul K) some years after. So the targets are very similar.

The weeds they chose are bicarb users though, not obligate CO2 gas users, say like all moss and liverworts species.
You could also compare the effects of one or two species of each type for CO2/Bicarb use and then measure the O2 production.

It probably is my ecological background, but If I was purely growing aquatic plants in an aquaria with the aim of growing the "best" plants, (and I'd agree that many of the plants illustrated couldn't be any better condition than they are), I would have no qualms about growing them with plenty of light, an added carbon source, ammonium nitrate as a nitrogen source etc., but personally I wouldn't do it in a planted aquaria with fish and/or inverts, and I couldn't advise any-one else to do it either.

Dose makes the poison.
Respiration is also a 2 way street, both O2 and CO2 needs addressed, not just one, or the assumption that "less is best". It's more a question of management and is there really any significant risk if the NO3 is say at 30ppm vs 1ppm?

If not, then there's no need to such management and maintaining low NO3 in an aquarium.
How to test that? Use a canary. Crystal red shrimp, hyper sensitive invert due to heavy inbreeding, easy to bred so plenty of culls available to test. Same approach can be used with plant species also, pick a sensitive one to test with or a collection of the wimply touchy species.

If there is no significant difference between say 5 ppm NO3 and say 30ppm, then why bother obsessing and going to more labor if there is no benefit? Environmental management does not operate on hearsay and myth. They test and check to see if there is some risk based on some model and hopefully improve over time and get better and better, not test will be perfect or answer any ultimate truth, only get a bit closer.

Complete elimination is not practical, nor required.
This(elimination) is an often used argument and hyperbole used in the Environmental field and the aquarium hobby on both sides.

I've probably said all that I can usefully say now, so I'll go back to "lurking", but I'm sure I will carry on enjoying the vast majority of posts.

cheers Darrel

I think the general notion you have is well placed and caring, so explore it, see what you think, what the evidence, what test you can cook up and try out and see. Do they make sense? Can you falsify a hypothesis you make? How might you make a reference to compare to? Demonstrate, prove it to yourself, your own eyes. Then you have learned something, challenged your own and gone down the path.

Classrooms and aquariums are very useful tools for teaching such concepts.
Then you see the range/results.

So post to your heart away

Regards,
Tom Barr

 

[plantbrain]

BTW, since you teach, I think the phytometer is an excellent tool and something even middle school kids can do at some level, to college grad level. Wetland plants can be used and grown in various sediments, salinities (marine salt or ethylene glycol etc for water potential), emergently so there's no interaction with CO2 demand/limitations/foliar nutrients.

Those intenractions can/could be added later, subsequently if you wanted to.

You can measure the N and P in the tissue, various organs, LAI, %OM, root shoot ratios etc etc and do analysis there.

BTW, no single management method shall be all things to all people, there's also a human factor in there that is huge.
So learn several method to have several management tools available to help various management goals.

I do.

Hopefully more will try different approaches and then fairly compare the trade offs.
Many are trying the non CO2 methods out after first doing the higher light/CO2 enrichment methods.

This aquarium has not seen a water change in 2 years:



No CO2, fish waste recycle, they do add a small amount of ferts, but demand is also small, export is via plant trimming, very low input, high efficiency, the sustainable index is more than any other type of aquarium BTW.

No water changes, low labor input, no testing, refill water, trim once every 2-3 month, feed fish.
Even plain fish only systems need more work than that.

I have a non CO2 Zebra pleco tank:


I'll add some floating emergent plants to the wood, much like a snag in a river with emergent plants stuck:



Another good paper is Madsen and Cedergreen 2002:
http://www.ingentaconnect.com/content/b ... 2/art00011

Callitriche cannot use Bicarb as a DIC source.

Good paper.

Looks at water column and Ole also did some work in Danish streams to this same effect.

Sediment and the water column both are good sources.
I use them both for management, not just one/or the other.
Both must be considered when looking at any system where aquatic plants/algae are growing.
Some folks do not, hobbyists have few methods to measure sediment sources, only the water column, so it's hard to blame them for fingering the water column to blame.

Here's a neat paper also about algae, nutrients, and macrophytes in a more applied aquarium (tropical to subtropical, similar plants species, temps, depths etc)

http://fishweb.ifas.ufl.edu/Faculty%20P ... ophyte.pdf

Not much correlation with algae, plants, submersed or otherwise and nutrient state of the lakes.
Very low R squared values across the board.

Seems like high N or P is a poor model to use for planted aquarium and algae, and trophic status.
The paper is certainly more applied to hobbyists plant species, temps, depths, algae + plants together, than any others I've run across. High number of lakes with plants in there. So good comparative results also.

They did not look at CO2, although Crisman is wondering about that the last 2-3 years.
Give the papers a good read and see what you think.




Regards,
Tom Barr

 

[dw1305]

Hi all,
Tom thanks for the references and phytometer picture, we are a bit limited with what we can do with our postgraduate trainee science teachers (by the "National Curriculum"), but we do regularly do one other photosynthesis experiment, using the wonderfully entitled "algal balls", details here <http://www-saps.plantsci.cam.ac.uk/articles/broad_light.htm>.

I'm hoping to get the Aquaria set back up in the Lab., so I'm looking for teaching project possibilities arising from these, so far I've got agreement to set up a "Winogradsky column" http://www.biology.ed.ac.uk/research/groups/jdeacon/microbes/winograd.htm, but I haven't got any further.

cheers Darrel

 

[CeeBee]

It's a pity people don't obsess over whether they have excess light. Then there might actually be some progress.

Salient point!

I can attest to this being the truth. I recently decided to increase the lighting period of my second lighting beam and am now wishing I hadn't due to a resurgence of BBA and what I think might be brown algae (not really getting why I've got the brown algae though). I only increased the time on the second beam by 1 hour.

It was all going so well but I had to go and tweak it 🙁