GSA and temperature

[sWozzAres]

I've been trying to get my head round this study...

http://www.plantsci.cam.ac.uk/Haseloff/ ... aham86.pdf

It studies the effect of light intensity, photoperiod and temperature on the ability of GSA to reproduce. They use Coleochaete Scutata. The conclusion seems to be that neither light intensity nor photoperiod are significant in triggering GSA to produce spores, but temperature is highly significant. They have some nice 3d graphs!

GSA zoosporogenesis is a seasonal thing that is triggered in spring when the temperature rises. Optimum temp for propagation is between 20-25c and a suggestion that Coloechaete Obicularis (I think the GSA we have in our tanks) is triggered by a lower temperature because it appears in lakes and stuff earlier than Scutata.

They also noticed that zoospore release starts shortly after the photoperiod begins.

With a layman interpretation of this scientific study extrapolated into a tank environment, it's easy to think that GSA could be triggered by a WC while the lights are on.

The study is from 1986, but it's interesting...

 

[Brenmuk]

The abstract mentions exposure of COLEOCHAETE SCUTATA to 20c for one to several days. I think in a heated tropical fishtank it would take a matter of hours not days for the water to return to 'tropical' temps even if you did a 50% W/C with cold water.

Might be more relevant if you are converting from a cold water system to a tropical system.

 

[ceg4048]

Also one has to be careful with the extrapolation because the context of the study is not in a planted aquarium. So the interactions of various factors do not translate well. First, it's not clear if this species is in fact our GSA. Second, we do know that the spore production must have some light threshold and that high light is also having a negative effect on the plants. We know that our GSA triggers on poor levels of CO2/PO4 so there's some interaction going on in the tank that may not be accounted for in the study. That's why, for our purposes it's better to concentrate on plant health because algae is a secondary effect of poor health.

Cheers,

 

[sWozzAres]

Agreed, the study was more about noting growth (by manually counting germlings) over many combinations of light/period and temp so I would assume they ensured their nutrients weren't limited. If temperature was triggering then it's not much help in the tank since the trigger starts at 10C and growth reaches a maximum at 20-25C which doesn't really help in a tropical tank.

However they also found that growth effectively stopped at 30C which is something we can experiment with.