Legal Levels of Herbicides Dangerous for Stream Macroalgae

The spraying of herbicides to eradicate weeds has long been regular practice for farmers around the globe. The routine dousing of fields to make space and save nutrients for crops has resulted in runoffs into nearby streams. These waterways have received the bulk of the weed-killing chemicals. There have, however, been few studies into the effects of the chemicals on organisms within the water.

Legal Levels of Herbicides Dangerous for Stream Macroalgae

A Brazil-based study has recently examined the effects of glyphosate-based-herbicides on certain types of green macroalga, which are common in streams around the globe. The study looked into whether the macroalga would be sensitive to these chemicals and whether their photosynthesis, respiration and chorophyll levels would be affected. Professor David Garbarry, the editor of Phycologia stated, “This paper provides an important contribution to our knowledge of the environmental toxicology of glyphosate-based herbicides in freshwater aquatic systems.”

The glyphodsate-based herbicides are among the most popular weed killers used around the world. Large amounts of these chemicals runoff into waterways, thus exposing the ecosystems to the effects of the chemical agents. A number of previous studies found glyphosate contamination in the U.S., French, Canadian and Argentinian waterways. This research did not include studies into the effects of the herbicides on macroalga. It is the macroalga that offers a basis for monitoring the health of rapidly moving fresh water. Within streams, these organisms are vital for cycling nutrients and increasing plankton.

This new study examined several concentrations of technical-grade- glyphosate, Roundup® weed killer, and aminomethylphosphonic acid (AMPA) to discover how they affect Nitella macrocarpa var. wrightii, which is a green algae found around the globe. These samples were collected from a fresh waterway in south-western Brazil. The test authors found that, when combined together, glyphosate and Roundup® strongly reduced algal photosynthesis. Ciro Cesar Zanini Branco, the author of the test, stated, “Such effects are related to the concentration of the active ingredient and also to the exposure time. These impacts were observed even at the concentration levels allowed by Brazilian regulations.” AMPA, in contrast, actually boosted photosynthesis. What is called ‘dark respiration’, which is respiration occurring regardless of light, also increased via AMPA treatment. The study also found less chlorophyll when AMPA and particular levels of glyphosate were administered.

What is very apparent, is that the performance of the algae was affected by the herbicides.

What is very apparent, is that the performance of the algae was affected by the herbicides. The form of the herbicides, as in how much glyphosate, glyphosate plus Roundup®, or AMPA they contain, is crucial in assessing the intensity of the effects upon the algae. The authors clearly noted that, even legal concentrations of Roundup® in Brazilian waters “may present significant environmental risks”.

Could this form the basis for compensation and legal action to take place? Stay tuned to this space to find out more.

Full text of the article “Assessment of the Potential Toxicity of Glyphosate-Based Herbicides on the Photosynthesis of Nitella microcarpa var. wrightii (Charophyceae),” Phycologia, Vol. 55, No. 5, 2016, is now available.

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About sudhahamilton

Sudha Hamilton is the publisher of Eco Living Magazine He loves writing and reading about the things that matter. Working predominantly as natural health writer, he has been published in WellBeing, Conscious Living, and Eco Living Magazines. Having spent many years on a spiritual path, originally in the company of Osho, he has an abiding interest in the human condition. From the micro to the macro he seeks to understand the truth that lies beneath the artifice and constructs, which daily delude us all.

Posted on September 1, 2016, in Eco Living. Bookmark the permalink. Leave a comment.

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