Friday, January 04, 2013

Revegation Practice and Glyphosate

Recently I raised some concerns on fb regarding the current practices used for revegatation work along creek banks in my local area.

Basically, the practice is to use a glyphosate based product to spray the area to be replanted, and perhaps repeat this at intervals.  Once cleared, the young plants used in the revegatation process then have a better chance of becoming established.

What concerned me about this, other than the fact that I believe the use of chemicals in such a way is not a sustainable practice and is in fact somewhat contradictory to the idea behind the revegatation process, was that we may be doing more harm than good.

Recently in this area spraying has taken place alongside the Monbulk Creek, which is a valuable platypus habitat, with the intention of improving the targeted area by revegatating with indigenous, riparian, species.

This led me to wonder what affect glyphosate based products may have on the food sources of the platypus, their general health and their long-term reproductive potential.

Although not much is known about the platypus in comparison to many other mammals, from reading Platypus, by Tom Grant I now know a bit more than I used too.  This led to my having specific concerns around the possible contamination of their food sources.

Commercial glyphosate formulations are known to:

  • significantly impaired growth and reproductive capacity in several fresh water invertebrates, including daphinia and shrimps, as well as amphibians such as frogs;
  • reduce survival rates and egg production in freshwater snails and also be a genotoxin, meaning it can cause damage at a cellular level;
  • also be genotoxic to certain fish species, with both the POEA and glyphosate components showing this potential on their own;
  • genotoxic to caiman;
  • increase the proliferation of certain parasites that spend part of their life cycle in freshwater snails.

The daphinia study linked above concluded:

"The results indicate that aquatic invertebrate ecology can be adversely affected by relevant ambient concentrations of this major herbicide. We conclude that glyphosate and Roundup toxicity to aquatic invertebrates have been underestimated and that current European Commission and US EPA toxicity classification of these chemicals need to be revised."

The Australian Platypus Conservancy have been really helpful with the concerns I had and a representative of the APC advised me that repeated studies have shown that glyphosate doesn't bioaccumulate in mammals, fish or birds and that there is no reason to think that glyphosate used in a responsible manner would be dangerous to the platypus.

I myself have found no studies that claim bioaccumulation in mammals, however it is known to be toxic to inverts, amphibians, fish, mice, rats and caiman amongst others.

There has also been a lot of concern in countries, such as Argentina where Roundup Ready seeds are used and aerial spraying of crops is common, over increasing numbers of miscarriages, birth defects and cancers being attributed to use of Roundup and other glyphosate formulations.

Ingestion of commercial formulations of glyphosate, such as Roundup, are also a favourite way for Indian farmers suffering poverty and disenfranchisement to commit suicide.

The glyphosate itself may be safe but the surfactants used, polyoxyethyleneamines (POEA) in the main, are very toxic.

It is these surfactants that led to recommendations in Australia to avoid use of Roundup products in or near water, due to it's toxicity on frogs and tadpoles.

Roundup Bioactive has less "irritant" and "toxic" surfactants and is therefore deemed safe for aquatic use.  It does not contain POEA.  It may be some time however before we know for sure whether this product is really "safe" for use.  It took several decades of Roundup usage before the general public became aware of the health concerns surrounding it....

but back to the original point:  revegatation work and whether glyphosate products, Roundup in particular, should be used.

Just consider...

  • the logic of spraying entire areas, killing off both exotic and indigenous vegetation, so you can plant more indigenous species...
  • the damage to aquatic plants, algaes and consequently food sources for many of the creatures that form the basis of aquatic food webs...
  • let alone the harm caused to those creatures directly...
  • the fact that glyphosate is only "neutralised" in soils with colloidal properties because of the natural adsorbtion process, if you're working with soils with low organic matter or clay contents, then leaching can occur into nearby water sources...
  • no adsorbtion means that glyphosate may become affective as a pre-emergence herbicide and result in reduced establishment of the new plants and damage to those herbaceous perennials that may have been about to commence a growing season...
  • no adsorbtion and it's water solubility means it can move through the soil and be taken up by plants...
  • clearing all vegetation from a site encourages weed seeds that are already present to germinate and you're back to square one...
  • then there's the increasing incidence of Roundup resistant weeds (5 in Australia so far)...
  • clearing all vegetation from a site also leaves the soil exposed to the elements, open to erosion and degradation....
  • exposed soil very quickly loses any organic matter content it holds through the process of oxidation.  Organic matter is perhaps the most important thing for the health of your soil and the chances of your new plants becoming quickly established
Oh, and there goes your soil carbon reservoir and you're now increasing the contribution to global warming that you've already made by buying the chemicals you used in the first place!

Surely there has to be a better, more sustainable, way?

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