Scientist is anxious about the health of our natural river systems

Through undertaking many investigations into the causes of aquatic animal health disorders, Matt Landos has seen numerous cases where pesticides have played a contributory role and he has taken a special interest in the role of contaminants in impacting fisheries and aquaculture. In 2000, Dr Matt Landos BVSc(HonsI)MANZCVS, took a position with NSW Fisheries DPI as a veterinary officer for aquatic animal health. "That role involved investigating fish kills, undertaking research to develop the silver perch and other aquaculture industries, and working on biosecurity policy," Dr Landos said. He subsequently started a consultancy business in 2005 and is a director, Future Fisheries Veterinary Service Pty Ltd, an Associate researcher, Sydney University, Faculty of Veterinary Science, and an Adjunct senior lecturer, Charles Sturt University, School of Animal and Veterinary Sciences. Through his research, Dr Landos is concerned about the amount of pesticides entering our streams and food chain which are ultimately having and adverse effect on fish, prawns and oysters and our bodies. He said the exposures in aquatic animals happen through the water interface which can be contaminated by spray drift, agricultural run-off, contaminated rainfall from vapour drift and contaminated groundwater and in aquaculture where residues can be in raw materials which are included in the fish feed. "It is important to recognise that the spectrum of contaminants in water is almost never just pesticides- so the picture is complicated with water now widely contaminated with surfactants, PFAS chemicals and PBDE flame retardants from wastewater/stormwater pathways, pharmaceuticals, microplastics, hydrocarbons and personal care products," Dr Landos said. The power of analytical laboratories has continued to improve with time to identify the fate of pesticides after application, and Dr Landos said it is now unarguable that glyphosate moves off the paddock where it was applied. He is also anxious about the escalating human health issues, but is cautious to lay blame. "Pesticides are likely to be a significant contributor to conditions such as Parkinsons, Breast and Prostate cancer, obesity, diabetes and attention deficit hyperactivity disorder (ADHD), but are not the only contributor- as complex mixture exposures are occurring," Dr Landos said. "The oyster industry is another example where pesticides and their spray adjuvants are a contributor to stress. "This is important as more and more oyster growing areas are being abandoned due to the oysters failing to survive." He added that the state of the fish stocks is catastrophic, and he has recently heard from Victoria's lead research agency, The Arthur Rylah Institute for Environmental Research (ARI), stating that our native silver perch is functionally extinct from the northern Murray Darling Basin, when speaking at the World Recreational Fishing Conference in Melbourne, held on 20-22 February. The entry of pesticides in our streams should not be underestimated. Dr Matt Landos, director of consultancy Future Fisheries Veterinary Services Pty Ltd said there are many impacts caused by use of pesticides in the landscape and not just in agricultural production. They include, the promotion of blue-green algal blooms- which create a toxicity hazard for stock drinking the water and wildlife. "It also creates a hazard for people living near the blooms due to aerosolised toxins," he said. "And these blooms create challenges for municipal water suppliers to filter out the toxins to make water palatable and potable. These blooms when they die can contribute to deoxygenation of the water." The decline of insect abundance and biodiversity is another issue because insects are a key part of the aquatic food webs. "When you have less bugs there is less food for fish to eat, which means far fewer fish survive," Dr Landos said. "Insects also often have life stages in waterways which play ecological roles in keeping the sediments of rivers healthy." Dr Landos further pointed to the impact pesticides have on the food which is critical for the survival of the native fish larvae, and that many pesticides are endocrine disruptors at sub-lethal exposures, and contribute in complex mixtures to disturbances of reproduction, through reduced gamete production, and changes to behaviors of fish. "Pesticides and other contaminants are contributing to reduced resilience to fish diseases," he said. "There is an urgent need to change the regulation of pesticides as the current system is unsafe. "The mounting costs to human health and the environment are not being counted."