Structural and Functional Effects of Herbicides on Non-Target Organisms in Aquatic Ecosystems with an Emphasis on Atrazine

Adverse Effects of Herbicides on Freshwater Zooplankton

“…Few if any environmentally relevant concentrations have been shown to have direct effects on zooplankton, fish, or amphibians in the laboratory (Fairchild, 2011). However a recent review by Rohr & McCoy (2010) concluded that atrazine produces indirect and sublethal effects on fish and amphibians at environmentally relevant concentrations.…”

“…The result of this diagnosis is a scattered picture with many uncertainties, but also with many opportunities for environmental toxicology research. Perhaps the fact that many authors argue that there are no direct effects of herbicides on freshwater zooplankton at environmental concentrations (Fairchild, 2011) or that herbicides do not represent a threat to aquatic communities (Relyea, 2005;Golombieski et al, 2008) has discourage research in this area. However, these authors failed to consider a series of circumstances that might be consider while analyzing the potential of herbicides for adverse effects:…”

“…Lethal toxicity in amphibians has been demonstrated (Reylea, 2005). Still, some authors pose serious doubts about the results suggesting direct and indirect effects of herbicides on invertebrates, amphibians and fish exposed to environmentally relevant concentrations (Fairchild, 2011). These doubts have to be clarified using well designed experiments that include effects on endocrine and immune function.…”

“…Individuals of Simocephalus vetulus (Crustacea) may have died in the diquat treated ponds because of lower oxygen supply that benefited Daphnia longispina because increased its populations (Brooker & Edwars, 1973). Fairchild (2011) argues that atrazine did not produce neither direct nor indirect effects on aquatic invertebrates/vertebrates. However a recent review by Rohr and McCoy (2010) concluded that atrazine produces indirect and sublethal effects on fish and amphibians at environmentally relevant concentrations.…”

“…Indirect effects of herbicides are defined as observed effects on consumer populations in freshwater invertebrates that are not caused by direct toxicity but due to adverse effects on primary producers such as algae and macrophytes (Fairchild, 2011). An herbicide induced death suddenly because cuts off oxygen supply during a period when growth and reproduction by freshwater zooplankton are taking place.…”