Presentation by Dr John Abbot

Many studies have focused on measuring the levels of pesticides, particularly herbicides such as diuron, atrazine and simazine, in rivers and coastal areas associated with GBR catchments.  Modern analytical instruments can detect very low levels of these chemicals. It is known that these chemicals can be transported from agricultural areas, into GBR catchment waterways, particularly during flood events following periods of heavy rainfall. 

It is much less certain whether the presence of these chemicals in water or sediments cause environmental harm.  Reported investigations have focused on possible impacts of herbicides on mangroves, seagrass and coral.    

Claims that herbicides have caused dieback of mangroves in the Pioneer and Fitzroy River estuaries are examined, as a case study.  This illustrates the importance of critically reviewing evidence presented for proof of causal links.  It stresses the importance of considering factors such as bioavailability, and whether appropriate data has been collected to justify causal inferences from any correlations presented.   Understanding an environmental scenario in the context of the wider scientific literature is essential, and assessing the significance of any experimental investigations used to support conclusions from field investigations.      

It is hoped to encourage researchers to question evidence critically where claims are made for causation of environmental impacts.