6 replies to this topic

[WheelsOC]

So I'd like to collect some of the native aquatics around me, but I worry. Virtually every natural body of freshwater around here is a creek or a bog fed by a creek, and they all have an orange slime. It seems to grow out of the sand and collect at the edges, on plant stems, basically anything it can stick to. It's especially prevalent in slower flows or still waters.

I don't know if it's a bacteria, a fungus, or a kind of algae but it eventually chokes anything submerged.

 

It might be colonies of the same iron-munching bacteria that sporadically pop up in our residential well, necessitating chlorine shock treatments once or twice a year. Our soil here is mostly rust-rich Piedmont red clay, chemically weathered from the underlying iron-filled and calcium-poor bedrock.

 

Whatever it is, it's unsightly and kills plants so I'd like to keep it off of anything I happen to collect. I brought in some Hydrocotyle verticillata cuttings a few weeks ago and plopped them into a shallow container with pre-boiled water, a bit of calcium chicken grit, and some oven-sterilized soils. Now the orange scum is evident in the water and forming a mat around the submerged portion of the cuttings and their shoots, and the leaves are starting to turn yellow and wilt away. It didn't come in through the water or the soil, so I'm thinking it probably hitched a ride on the untreated plants.

 

What's the recommended method of killing unwanted scums on wild-caught plants anymore? Is it still potassium permanganate or hydrogen peroxide solution?

[gerald]

The rusty slime is indeed iron-oxidizing bacteria.  It thrives where anaerobic iron-rich groundwater seeps into oxygenated water, and Fe+2 is oxidized to Fe+3 (rust).  I'm guessing the submerged soil in your Hydrocotyle container has become anaerobic and dissolved Fe+2 is rising to the surface.  I've never heard of it harming plants.  I've collected river sand, plants, and fish from sites with rust-bacteria for many years and never had a noticeable growth of it in tanks.

[mattknepley]

Thanks for the o.p. and the response. I too have seen this particular phenomena and wondered at it. Glad to know it is not so malevolent a situation as I sometimes supposed.

[gerald]

Sites where rust-slime is unusually thick are probably also nutrient-enriched from farm runoff, septic systems, etc.  I also remember following one tiny rust-choked creek upslope years ago, and finding a car junkyard at the head.  I think that one was near Jonesville NC.

[Irate Mormon]

Orange slime.  I sell that stuff, $2/gram.  A bargain at any price!

[WheelsOC]

The rusty slime is indeed iron-oxidizing bacteria.  It thrives where anaerobic iron-rich groundwater seeps into oxygenated water, and Fe+2 is oxidized to Fe+3 (rust).  I'm guessing the submerged soil in your Hydrocotyle container has become anaerobic and dissolved Fe+2 is rising to the surface.  I've never heard of it harming plants.  I've collected river sand, plants, and fish from sites with rust-bacteria for many years and never had a noticeable growth of it in tanks.

 

 

Sites where rust-slime is unusually thick are probably also nutrient-enriched from farm runoff, septic systems, etc.  I also remember following one tiny rust-choked creek upslope years ago, and finding a car junkyard at the head.  I think that one was near Jonesville NC.

 

Good to know! The container with the pennywort is just a small plastic foodsaver and the water is less than an inch deep. I threw in a bit of creek sediment from the collection site and a few grains of oyster grit for good measure, just to see if the plant would sprout from a small number of very short clippings.

 

My concern is that I'm trying to set up a Walstad style dirt tank with a cap of blasting grit. If there's an issue with parts of the substrate becoming anaerobic, I'd like to avoid having blooms of orange slime in the tank.

[gzeiger]

Pennywort will grow fine from small rooted clippings and sometimes from larger unrooted clippings. However, it is an obligate emergent. You'll have a hard time giving it the air it needs in a traditional aquarium.