Monday, June 7, 2021

Iron floc in streams is perfectly natural

 

Iron floc seeping from the stream bank

Floc is the fluffy material you see in some waterways, sometimes forming soft stalks. It is quite delicate and will break apart easily when disturbed so even though it may not be ‘aesthetically pleasing to the eye’ it is an important metabolic process that should be allowed to occur, and in fact is likely to be a very ancient process in the context of the development of life on earth (there is actually a good deal of research on different iron oxidizing bacteria, and it is a worldwide phenomenon). The harvested electrons by the bacteria provide energy for reproduction and other life-sustaining processes in the life of these single-celled organisms. A variety of species and sub-species of bacteria carry out this process. It requires oxygen, so these bacteria live and reproduce where iron-rich water flows out of the ground and is exposed to oxygen in the air. This is a completely natural process.

Interestingly enough, and it has not been worked out why, we find that giant kokopu are very fond of streams that have lots of iron floc, with good populations in some urban and perimeter urban Hamilton streams.

In this You Tube clip https://youtu.be/8w0kgAwv1Ps taken in the Gordonton arm (zone 3) of Mangaiti Gully stream you will see the iron floc floating about from the disturbance of the eels. A giant kokopu is visible at the end of the clip. Kōura / freshwater crayfish have been found a little downstream from this photo point. All indicating healthy stream fauna happily living among the iron floc.


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