Host mortality and variability in epizootics of Schistocephalus solidus infecting the threespine stickleback, Gasterosteus aculeatus

• Published in: Parasitology Vol. 137; no. 11; pp. 1681 - 1686
• Main Authors: HEINS, D. C., BIRDEN, E. L., BAKER, J. A.
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.09.2010
• Subjects: Alaska - epidemiology; Animal and plant ecology; Animal, plant and microbial ecology; Animals; Biological and medical sciences; Cestoda - growth & development; Cestoda - pathogenicity; Cestode Infections - epidemiology; Cestode Infections - mortality; Cestode Infections - parasitology; Cestode Infections - veterinary; Demecology; epizootic; Fish Diseases - epidemiology; Fish Diseases - mortality; Fish Diseases - parasitology; Freshwater; Fundamental and applied biological sciences. Psychology; Gasterosteus aculeatus; General aspects; General aspects and techniques. Study of several systematic groups. Models; Host-Parasite Interactions; intensity; Invertebrates; parasite index; Population Dynamics; Prevalence; Reproduction; Schistocephalus solidus; Smegmamorpha - parasitology; Smegmamorpha - physiology; threespine stickleback; Alaska; USA, Alaska; intensity; prevalence; epizootic; threespine stickleback; Schistocephalus solidus; parasite index; Gasterosteus aculeatus; population dynamics; Prevalence; Mortality; Parasite; Host; Epizootics; Vertebrata; Pisces; Population dynamics
• ISSN: 0031-1820; 1469-8161
• DOI: 10.1017/S003118201000048X

An analysis of the metrics of Schistocephalus solidus infection of the threespine stickleback, Gasterosteus aculeatus, in Walby Lake, Alaska, showed that an epizootic ended between 1996 and 1998 and another occurred between 1998 and 2003. The end of the first epizootic was associated with a crash in population size of the stickleback, which serves as the second intermediate host. The likely cause of the end of that epizootic is mass mortality of host fish over winter in 1996–1997. The deleterious impact of the parasite on host reproduction and increased host predation associated with parasitic manipulation of host behaviour and morphology to facilitate transmission might also have played a role, along with unknown environmental factors acting on heavily infected fish or fish in poor condition. The second epizootic was linked to relatively high levels of prevalence and mean intensity of infection, but parasite:host mass ratios were quite low at the peak and there were no apparent mass deaths of the host. A number of abiotic and biotic factors are likely to interact to contribute to the occurrence of epizootics in S. solidus, which appear to be unstable and variable. Epizootics appear to depend on particular and, at times, rare sets of circumstances.