Synergistic effects of glyphosate formulation and parasite infection on fish malformations and survival
Article first published online: 17 FEB 2010
© 2010 The Authors. Journal compilation © 2010 British Ecological Society
Journal of Applied Ecology
Volume 47, Issue 2, pages 498–504, April 2010
How to Cite
Kelly, D. W., Poulin, R., Tompkins, D. M. and Townsend, C. R. (2010), Synergistic effects of glyphosate formulation and parasite infection on fish malformations and survival. Journal of Applied Ecology, 47: 498–504. doi: 10.1111/j.1365-2664.2010.01791.x
- Issue published online: 8 MAR 2010
- Article first published online: 17 FEB 2010
- Received 11 October 2009; accepted 20 January 2010 Handling Editor: Chris Frid
- fish populations;
- multiple stressors;
- toxicity tests
1. Anthropogenic pollution and disease can cause both lethal and sub-lethal effects in aquatic species but our understanding of how these stressors interact is often not known. Contaminants can reduce host resistance to disease, but whether hosts are impacted at environmentally relevant concentrations is poorly understood.
2. We investigated the independent and combined effects of exposure to the common herbicide glyphosate and the trematode parasite Telogaster opisthorchis on survival and the development of spinal malformations in juvenile Galaxias anomalus, a New Zealand freshwater fish. We then investigated how exposure to a glyphosate concentration gradient (0·36, 3·6, 36 mg active ingredient (a.i.) L−1) affected the production and release of the infective cercarial stage of the parasite by its snail intermediate host Potamopyrgus antipodarum.
3. Survival of juvenile fish was unaffected by exposure to glyphosate alone (at an environmentally relevant concentration; 0·36 mg a.i. L−1) or by T. opisthorchis infection alone. However, simultaneous exposure to infection and glyphosate significantly reduced fish survival.
4. Juvenile fish developed spinal malformations when exposed either to infections alone or to infections and glyphosate, with a trend towards greater severity of spinal malformation after exposure to both stressors.
5. All snails exposed to the highest glyphosate concentration (36 mg a.i. L−1) died within 24 h. Snails exposed to a moderate concentration (3·6 mg a.i. L−1) produced significantly more T. opisthorchis cercariae than snails in the control group or the low concentration group (0·36 mg a.i. L−1; the same concentration as in the fish experiment).
6. Synthesis and applications. This is the first study to show that parasites and glyphosate can act synergistically on aquatic vertebrates at environmentally relevant concentrations, and that glyphosate might increase the risk of disease in fish. Our results have important implications when identifying risks to aquatic communities and suggest that threshold levels of glyphosate currently set by regulatory authorities do not adequately protect freshwater systems.