Prevalence and seasonality of Zoothamnium duplicatum (Protozoa : Ciliophora) epibiont on an estuarine mysid (Crustacea : Mysida) in tropical mangrove brackish water

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The estuarine mysid Mesopodopsis tenuipes (Crustacea: Mysida) was often found carrying the peritrich ciliate Zoothamnium duplicatum (Protozoa: Ciliophora) on its body. The prevalence and seasonality of this association were studied on the basis of a year-round survey conducted in the Merbok mangrove brackish water in north-western Peninsular Malaysia from March 2005 to February 2006. The frequency of mysids hosting ciliates varied from 0 to 57.3%, with an annual mean of 17.0%. Juveniles showed a significantly lower prevalence of ciliates than adult mysids. There was no difference in infestation prevalence between the sexes. An epibiotic renewal process could be assessed through observations in breeding females. The infestation prevalence and loads were appreciably lower in the females carrying earlier stages of embryos than in those with developed ones, indicating that zoothamnid ciliates may require two or more days to reach a saturation phase in terms of prevalence when ciliate reproduction is high. This, in turn, suggests that the high moulting frequency of the tropical mysid may inhibit high colonisation pressure by the epibiont. A periodic seasonal trend was not determined, although mysids in lower salinity conditions were more likely to carry epibionts than those at higher salinities.
2010-02-01