Associations between fish reproductive cycle and t

Authors: Andrea Šimková Jiří Jarkovský Božena Koubková Vlastimil Baruš Miroslav Prokeš

Publish Date: 2004/11/25

Volume: 95, Issue: 1, Pages: 65-72

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Abstract

The parasite fauna of the stone loach Barbatula barbatula was investigated monthly from May to December 2001 Four parasite species were recorded Gyrodactylus spp Monogenea Tylodelphys clavata Digenea Proteocephalus sagittus Cestoda and Raphidascaris acus Nematoda The changes in the seasonal dynamics of parasite infection were investigated throughout the 8 months The potential effect of the reproductive investment of the host measured by gonad mass and gonadosomatic index GSI on the parasite infection was tested against the prediction that during periods of high reproductive investment beginning of the breeding period or forming gonads after breeding the fish are more susceptible to parasite infection Differences between parasite loads between genders were also hypothesized Seasonal differences in infection were observed for all parasite species studied The values of GSI showed a pattern of energy accumulation in the prereproductive period and at the beginning of breeding a decrease during breeding and an increase in the postbreeding period A similar pattern was observed for parasite abundance a strong or weak increase in spring and/or autumn and a decrease during summer July and August Positive correlations between the abundance of Gyrodactylus spp and R acus and both gonad mass and GSI were found in females after eliminating the effect of fish weight Our results suggest that stone loach females are more susceptible to parasite infection in periods of higher reproductive investment The main factor determining the infection of T clavata was fish size The abundance of P sagittus was positively correlated with GSI in the total fish sample with no detectable effect of sex or fish weight The increase in cestode infection in spring supports the hypothesis that the parasite life cycle could by synchronized with the beginning of host reproduction probably induced by increasing fish hormone levels in the springThis study was supported by the Grant Agency of the Academy of Sciences of the Czech Republic project no A 6093104 to MP BK and VB Grant Agency of the Czech Republic no 524/01/1314 to VB Research Project of the Masaryk University no MSM 143100010 and Improving Human Potential Programme COBICE project no 510 AŠ was funded by the Grant Agency of the Czech Republic project no 524/03/P108 The stay of AŠ in France was funded by NATO fellowship We would like to thank Serge Morand and JeanFrançois Martin from the Centre of Biology and Management of Populations Montferrier sur Lez France for useful comments on the first draft We are very grateful to Iveta Douglas and Carey O Cunningham from the FRS Marine Laboratory Aberdeen Scotland for correction of the English The experiments comply with the current laws of our country

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