A growth-promoting hormone used worldwide in the beef industry has been found to affect the sexual behaviours of fish at a very low concentration in waterways – with potentially serious ecological and evolutionary consequences.
Researchers from Monash University, in collaboration with researchers from Åbo Akademi University in Finland, have found that the steroid 17β-trenbolone – used on livestock to increase muscle growth – alters male reproductive behaviour in guppy fish (Poecilia reticulata).
This androgenic growth promoter is part of a group of contaminants called endocrine disrupting chemicals (EDCs) that enter the environment through a variety of sources – from discharge of household waste to agricultural run-off and industrial effluent.
Lead researcher Michael Bertram, a PhD student in the School of Biological Sciences at Monash University, said over the past few decades concern has been mounting over EDCs, and that their contamination of aquatic habitats is a serious environmental problem.
“Endocrine disrupting chemicals (EDCs) are cause for concern given their capacity to disturb the natural functioning of the endocrine (hormonal) system, often at very low concentrations, with potentially catastrophic effects," MR Bertram said.
"Research until now has focused primarily on the morphological and physiological effects of EDC exposure. For the first time, our research has shown that exposure to an environmentally realistic concentration of 17β-trenbolone – just 22 nanograms per litre - is sufficient to alter male reproductive behaviour.”
The research shows exposure of South American native guppy fish to 17β-trenbolone affects the fish's breeding mate selection, which can profoundly affect individual populations and species, with potentially devastating long term evolutionary and ecological impacts.
Mr Bertram said that by illustrating the capacity of the agricultural contaminant to alter reproductive behaviour, the research demonstrated the possibility of widespread disruption of mating systems in wild populations.
