Phalaris, allelopathy and cyanobacteria (Microcystis)

[dw1305]

Hi all,
A bit of a strange one, but this has come my way (<"I worked, briefly,"> with the lead author): <"https://www.tandfonline.com/doi/full/10.1080/20442041.2024.2426388#abstract">

...... We investigated whether allelochemicals released from Phalaris root exudates inhibit Microcystis aeruginosa growth. We conducted experiments to disentangle the effect of the root exudates from living plants on resource competition and the potential role of microbiota in controlling Microcystis growth. We found that allelochemicals from root exudates and their inhibitory effect decayed over time. Results from filtration experiments and microscopic observations indicated that the removal of microorganisms (≥ 0.22 µm) allowed for the growth of Microcystis, suggesting that protists and rotifers may control Microcystis growth......

...... However, Microcystis growth was still suppressed in the unfiltered samples. This suggests there is another mechanism suppressing Microcystis growth in the unfiltered samples.
One possible explanation for this mechanism is the presence of protozoa and invertebrates in the root exudates. Microscopic observations and the identification of protozoa and invertebrates in the root exudate samples suggest that these organisms may be grazing on Microcystis cells. Another possible explanation is the production of antimicrobial compounds by the microbiota, which could suppress Microcystis cell growth ......

A quick summary would be that allelopathic exudates from the roots of Reed Canary-grass (Phalaris arundinacea) suppressed the growth of Microcystis (cyanobacteria, a "Blue green algae"), but this effect was most significant over time in the "presence of protozoa and invertebrates in the root exudates" ("unfiltered" in the figure below).



Castro-Castellon, A. T., Hughes, J. M. R., Chipps, M. J., & Hankins, N. P. (2024). Hormesis and Antagonism in Low-Dose Phalaris Allelochemicals during Microcystis Control. Inland Waters, 1–22. https://doi.org/10.1080/20442041.2024.2426388

cheers Darrel

 

[Teleos]

Hi Darrel, hi all
very interesting to read. However, I haven't quite finished reading it yet.

A little more to read
Epiphytic biofilms in freshwater and interactions with macrophytes (only short version available)

Very briefly summarized: Epiphytic biofilm plays an important role in freshwater ecosystems. Macrophyte morphology and characteristics influence epiphytic biofilm. Epiphytic biofilm and macrophytes form a highly interactive and complex platform.

 

[dw1305]

Hi all,

Epiphytic biofilm plays an important role in freshwater ecosystems. Macrophyte morphology and characteristics influence epiphytic biofilm. Epiphytic biofilm and macrophytes form a highly interactive and complex platform.

That would definitely be where I'm coming from, <"even in aquariums"> with just <"floating plants">. I think it is part of the reason why <"plants and time"> bring stability.

Some people are going to want to feel they are in control of all parameters, where my view would be, very much, create a frame-work, leave it mainly alone <"and they will come">.

It is also part of the reason for having the <"tank janitors"> adding <"leaf litter"> etc, it more closely replicates natural conditions and provides many more niches for <"micro and mesofauna"> and microbes.

It is also part of the rationale for having a relatively low nutrient set-up, <"maximal biological diversity"> usually occurs in mesotrophic <"situations">.

cheers Darrel

 

[Oldguy]

allelopathic exudates

I think that this is an important factor in planted tanks. Strong higher plant growth inhibits algal growth and vice versa. It may also be a factor in that some plants are 'difficult' for some but not for others. 'Old School' books often contain reference to plants being compatible or not. However difficult to separate this from nutrient and light requirements in our planted tanks, especially if like myself you only have the one tank.

All interesting stuff.

 

[dw1305]

Hi all,

Strong higher plant growth inhibits algal growth and vice versa. It may also be a factor in that some plants are 'difficult' for some but not for others. ..... However difficult to separate this from nutrient and light requirements in our planted tanks,

I think that is the <"really difficult one to sort out">, and we are probably never going to know exactly how <"all the ducks line up in a row">.

Some people are going to want to feel they are in control of all parameters, where my view would be, very much, create a frame-work, leave it mainly alone <"and they will come">.

That one really. I think it was one of the reasons why Diana Walstad called her book "Ecology of the Planted Aquarium" - <"https://www.amazon.co.uk/Ecology-Planted-Aquarium-Practical-Scientific/dp/0967377366">.

Strong higher plant growth inhibits algal growth and vice versa.

That is where I'd also start, get the plants growing. It is a bit like <"emergency first aid">, triage the plants first.

cheers Darrel

 

[Teleos]

Two further links to cyanobacteria:

This review highlights the properties of 25 toxin types produced by 12 different cyanobacteria genera. The review also covered strategies for reducing and controlling cyanobacteria issues.
Understanding the Risks of Diffusion of Cyanobacteria Toxins in Rivers, Lakes, and Potable Water

Cyanobacteria accurately sense the position of a light source
Cyanobacteria use micro-optics to sense light direction

You will also find many other similar articles. So you can easily spend several days reading. 😉