cheers DarrelBiological response to lake remediation by phosphate stripping: control of Cladophora
Parker, Julie E.; Maberly, Stephen C.
Freshwater Biology, Volume 44, Number 2, June 2000 , pp. 303-309(7)
The North and South Basins of Windermere, Cumbria, have experienced a large increase in concentrations of nutrients, particularly phosphate, since 1945 when detailed measurements began. Over-winter concentrations have increased from 1 to 3 mg PO4-P m-3 in the 1940s, up to 30 mg PO4-P m-3 in the South Basin of Windermere in the early 1990s where nutrient enrichment has been most marked. A visible manifestation of this `eutrophication' in recent years has been the production of a large biomass by the green filamentous macroalga, Cladophora. </li> <li level="2">
Since April 1992, tertiary chemical stripping of phosphate at the two sewage treatment plants on Windermere has reduced direct sources of phosphate to both basins. In the South Basin, over-winter concentrations of phosphate have fallen to values similar to those in the early 1970s.
The biomass of Cladophora has declined markedly in response to the reduced phosphate availability. Significant relationships were found between the annual maximum biomass of Cladophora and two measures of phosphate availability: the over-winter concentration and, more strongly, the day of year when the concentration fell below 1 mg m-3.
The annual biomass maxima of Cladophora since 1945, estimated from the regressions, showed a gradual increased potential for biomass production after 1965 as phosphate concentrations increased, followed by a striking and rapid biological response to lake remediation by phosphate stripping.
Exactly, that's why PMDD was unsuccessful and had to be modified to PMDD+PO4, which is hugely successful. The data is over a decade old, and at least one of the authors later admitted that the conclusions were wrong. There is always a danger of mis-correlation when you test hypotheses in the manner:Brenmuk said:The limiting phosphate idea fell out of favour a while ago see what Tom Barr has to say on the subject in this thread:-
If you do not have control, and if your measurement techniques are unsubstantiated in experiments, there will always be a question as to the validity of your conclusions, regardless of how compelling they may seem. And that's exactly what happened to Sears and Conlin. In the planted tank it has been demonstrated that there is no correlation between high PO4 levels and the appearance of cyanobacteria, and in fact cyanobacteria is now correlated to a deficiency in NO3.Despite the lack of controls on the various experiments, and the inability of the authors to directly measure phosphate in the aquaria, there is compelling evidence to support the hypothesis that all types of algae (including cyanobacteria) can be effectively controlled in planted aquaria by ensuring that phosphate is the factor limiting plant growth.
And I can only add what I've seen with my own eyes, excess PO4 does not cause algae .
I'm not trying to preach to the converted, but these are my own observations.
Well Chris I think it's important that the results of the principles we advocate can be corroborated independently by any individual. The results you see in your tank indicates that the results are repeatable, that they are not just the fantasy of a few extremist lunatics. Normal people, who follow the non-limiting principles see positive results so the evidence is unequivocal.
Scientists around the world, for generations, have linked nutrients to causality, to the point where it seems intuitive, yet, every day a growing number of hobbyists see just the opposite demonstrated in their tanks. In fact, we can break just about every one of their rules and instead of seeing increased algae, we see increased plant growth. Perhaps, someday, instead of insisting that the nutrient limiting is the way forward in our tanks, based on what they perceive is occurring in the worlds environmental systems, they may take a closer look at our tanks and decide that instead, perhaps they have an incomplete picture of the events occurring the worlds ecosystems
Well, I'm not looking for personal advancement, money or awards either, that's for sure. Not only that, but I'm not trying to prove what is. It's almost impossible to prove a theory. So I can't prove my theory correct, but the results do indicate that there is something wrong with the theory that nutrients cause algae.dw1305 said:As Clive says he is "mainly preaching to the converted" but If he feels his findings are of such significance that they will re-write one the fundamental principles under-pinning the science of Ecology, he needs to find an Academic Institution where his theories can be rigorously tested, under experimental conditions, and the results published in a peer reviewed journal.
I can't tell you whether he is right or not, and look forward to seeing the results, but if he is right, his work will invalidate the huge volume of scientific research over 150 years by many scientists choosing to work in a field which is very unlikely to win them much in the way of personal advancement, money or awards. As he has invoked the scientific process, I think it is probably time for him to "put up, or shut up".
In the Glades, the natural species is the Caldium grass, the added PO4 is changing things to a more Typha dominated system. Cattail can out compete Cladium easily when things are PO4 rich. when it's lean on PO4, then the Cladium does better. More Cattail is bad news for this natural system. Aquariums are not natural at all however.dw1305 said:Hi all,
The Everglades periphyton paper says that the end stage of the eutrophication process is a stand dominated by Typha, and that would be the end result in the UK as well, the victor is a large "chunky" plant, capable of rapid vegetative spread, with widely dispersed seeds and a linear growth response to nitrogen. As the paper explains the interaction between the periphyton, the higher plants and the environmental factors is a complex one. This also another case where the highly calcareous nature of the water and marl is a factor which limits the availability of many nutrients, and particularly phosphorus.
My point would be if you could return to the levels of macro-nutrients before eutrophication we would have a complex wetland with a high diversity of plants (including insectivorous ones like Utricularia, diatoms, filamentous green alga, cyanobacteria etc.) , and as eutrophication continues the diversity of all these plants will have declined as the ones with potentially quicker growth rates in eutrophic conditions, replacing those adapted to more nutrient poor "oligotrophic" conditions, and this replacement will occur in the algal community as well as amongst the macrophytes.
Nope, but it's a good thing to think about.ceg4048 said:Thanks Tom, you're right that these are not at all simple systems, and trying to extrapolate from one to another or from one to a tank may not bear fruit.
Well, overloading any system will kill off most natural states of diversity. So things like wastewater.spetic systems, hillbillies dumping their bed pans out in the back yard........The author in that trophic state indicator article even warned of that in his discussion. In any case, the lack of correlation between nutrients and algal blooms is a powerful insight, and it's exactly what we see - except for the observation that the lakes with the highest nutrient content were algae dominated, with SAMs "predictably" absent. He even mentioned that it was predictable. That was more than a bit of a surprise. Does that imply some kind of nutrient threshold in Florida lake systems?
Well, for the Glades, how do you reduce the PO4 down to 3-10ppb, Billion that issue.As far as tank dosing techniques, I suppose it goes back to what you've taught regarding goals and objectives. If the objective is in approximating a periphyton dominated environment, and if one focuses on biodiversity in terms of the population and variability of organisms in the biofilm, then that will drive a different strategy than one in which biodiversity is interpreted as the ability to maintain a high population of, and multiple species of weeds. The converted agree that this is horticulture with an aesthetic purpose.
Couldn't agree more. I've got so fed up listening to the EI brigade that I no longer bother posting.dw1305 said:I had become increasingly concerned that it had stopped being a forum where different experiences and options could be discussed, and had become a forum where you had to agree that "high nutrients, High CO2" was the answer to every question, and if you tried to post any other view your opinions were ridiculed, presumably with the intent of intimidating heterodox posters into not posting
|Thread starter||Similar threads||Forum||Replies||Date|
|All my algae has gone, and i want it back!||Algae||10|
|7||Can anyone identify this algae please||Algae||3|
|Can anyone tell me what this is keeps coming back||Algae||3|
|Can anyone help a first time aquascaper||Algae||16|
|S||Anyone identify this algae on my plants.||Algae||2|
|Please read the guidelines for Algae help!||Algae||0|