11 replies to this topic

[chocky]

I went to tomato lake in kenwick(?) yesterday. Noticed the lake had a crap load of green floaty plants. Looked like duckweed but smaller.
Anyone know what it is? I wouldn't want to feed my fish the stuff but just interested.


Sent from my iPhone using Tapatalk

[Peckoltia]

I'm not sure what the plant is in Tomato Lake at the moment. Tomato Lake had a pretty nasty case of botulism back in 2014, killed off a heap of ducks from memory. Nasty bit of water that. 

[Poncho]

It's an artificial lake that used to be swampy area around market gardens, so full of residual nutrients from years of applying copious amounts of fertiliser. Plus now it feeds from stormwater so will pick up nutrients from a wider catchment. Last time I went there it was a fairly successful looking piece of work regarding sump retrofit but it doesn't take much to disrupt the system and make it a nightmare to manage.

 

Chocky have you got any photos of the plant? You sure it's not clumps of green stringy algae?

 

The parkland lakes down in Mandurah have all responded to recent warmer weather and a few have green algal clumps forming on the surface over the past week or so because they are eutrophic. Tomato lake would be just as nutrient laden as these lakes if not more so.

[chocky]

I only took a photo but probably not close enough cos I had my dog with me and any closer she'd wanna jump in haha

I'll post it once I dig it up. Definitely not string algae. I have plenty of that.


Sent from my iPhone using Tapatalk

[chocky]

[Poncho]

looks like duckweed but hard to see

[malawiman85]

Azolla?

[bigjohnnofish]

azola starts to grow rapidly this time of year...and if its nutrient laden it'll go nuts.....

 

makes me wonder why they dont use something more vigorous to suck up the nutrients and then harvest the plants to make fertilizer like they do in other countries...

leaving a very clear and cleaner waterway for everyone....

[Buccal]

Wouldn't it be there because of someone mishandling the duckweed or whatever it is from their fish ponds or what have you.
Plenty of water birds around those areas to, to spread it.
As Poncho mentioned, the stormwater feed in throws out the balance, certainly is a high impact zone, I wonder what people's ground water is like close to that area.
But a series of treatment ponds filled with correct vegetation types can remove the nasties or lock it away or convert it, to better levels,, and maybe it is already working this way to some degree.

But it always has to be accepted that the vegetation will be contaminated, because they're doing their job.

[chocky]

No I don't think it was azolla. Definitely duckweed looking just smaller/finer leaves.

I assumed that it was someone mishandling duckweed too.

If it is duckweed ... is there a way to scoop it out and make it safe to feed my goldfish? Or just not worth the risk?


Sent from my iPhone using Tapatalk

[sydad]

Hi chocky,

 

I cannot see  detail of individual plants, so as are others I'm guessing. The floating plant could be Wolfia arrhiza, which is sometimes regarded as the smallest flowering plant in the world, with a green disc diameter of 0.5-1.5 mms, making it considerably smaller than duckweed (Lemna minor). That said, duckweed can be variable in growth, with many factors including nutrient availability and crowding affecting growth patterns and size.

 

The argument against it being Wolfia is the rarity of that plant, so i cannot imagine how it would come to be where it is, but if it is, you are fortunate because it is a superb vegetable feed. To answer your question re safety of feeding it to your goldfish, I would say that any harm is unlikely.

 

I remember  analyses being conducted some years ago on water from Tomato lake, and while the lake was certainly eutrophic at that time, there was no indication of significant heavy metal contamination: this is what would be of greatest concern. The lake was heavily infested with another floating plant (either Salvinia auriculata or Eichhornia crassipes (water hyacinth), I really cannot remember which, but there was enormous effort to remove it.

 

If you wish to use it as a food, just flush it thoroughly with fresh water while in a fine-meshed net. If you are still hesitant, why not collect some and use it as breeding stock. As i said earlier, if it is Wolfia, it is an ideal vegetable feed, and the effort would be worthwhile.

 

Syd.

Edited by sydad, 01 November 2016 - 01:34 PM.

[chocky]

Hi chocky,
 
I cannot see  detail of individual plants, so as are others I'm guessing. The floating plant could be Woolfia arrhiza, which is sometimes regarded as the smallest flowering plant in the world, with a green disc diameter of 0.5-1.5 mms, making it considerably smaller than duckweed (Lemna minor). That said, duckweed can be variable in growth, with many factors including nutrient availability and crowding affecting growth patterns and size.
 
The argument against it being Woolfia is the rarity of that plant, so i cannot imagine how it would come to be where it is, but if it is, you are fortunate because it is a superb vegetable feed. To answer your question re safety of feeding it to your goldfish, I would say that any harm is unlikely.
 
I remember  analyses being conducted some years ago on water from Tomato lake, and while the lake was certainly eutrophic at that time, there was no indication of significant heavy metal contamination: this is what would be of greatest concern. The lake was heavily infested with another floating plant (either Salvinia auriculata or Eichhornia crassipes (water hyacinth), I really cannot remember which, but there was enormous effort to remove it.
 
If you wish to use it as a food, just flush it thoroughly with fresh water while in a fine-meshed net. If you are still hesitant, why not collect some and use it as breeding stock. As i said earlier, if it is Woolfia, it is an ideal vegetable feed, and the effort would be worthwhile.
 
Syd.

Yes I have had wolfia before but failed to get a good amount growing. And have read about the benefits of it as food next time I'm there I'll take a better photo and take some home in a bag anyway.

There were heaps of it! Maybe covered about 20-30% of the lake?


Sent from my iPhone using Tapatalk