Trematode infection causes malformations and population effects in a declining New Zealand fish
Article first published online: 3 NOV 2009
© 2009 The Authors. Journal compilation © 2009 British Ecological Society
Journal of Animal Ecology
Volume 79, Issue 2, pages 445–452, March 2010
How to Cite
Kelly, D. W., Thomas, H., Thieltges, D. W., Poulin, R. and Tompkins, D. M. (2010), Trematode infection causes malformations and population effects in a declining New Zealand fish. Journal of Animal Ecology, 79: 445–452. doi: 10.1111/j.1365-2656.2009.01636.x
- Issue published online: 5 FEB 2010
- Article first published online: 3 NOV 2009
- Received 20 July 2009; accepted 11 October 2009 Handling Editor: Rob Knell
1. Animal malformations engender wide public and scientific concern because of associated environmental health risks. This is highlighted by increased incidence of limb malformations in amphibians associated with trematode infections and disturbance. Malformations may signal new emerging disease threats, but whether the phenomenon is broadly applicable across taxa, or has population-scale impacts, is unknown.
2. Malformations are widely reported in fish and, until now, have been attributed mainly to contaminants. We tested whether the trematode Telogaster opisthorchis caused severe malformations, leading to population effects, in Galaxias anomalus, a threatened New Zealand freshwater fish.
3. Experimental infection of larval fish caused increasing spinal malformation and mortality with infection intensity that closely matched field patterns. Field malformation frequency peaked in January (65%), before declining sharply in February (25%) and remaining low thereafter.
4. The peak occurred during a ‘critical window’ of larval development, with the decline coincident with a population crash, indicating that malformation was causing mortality in the field.
5. The occurrence of such critical developmental windows may explain why this mechanism of population impact has been overlooked. With global environmental stressors predicted to enhance trematode infections, our results show that parasite-induced malformation, and its population-scale impacts, could be more widespread than previously considered.