Yet More Parasite Count Analysis

Below is close to the final statement of the graph of gill fluke parasites found in telescope shiners at the Walls of Jericho (the graph can be enlarged by clicking on it, and the error bars are one standard error). With Jennifer's help (in SPSS on her computer) we ran a one way ANOVA of our eight months of gill fluke counts data followed up by a post-hoc Tukey HSD. The whole point of this is to determine if parasite infestation varies monthly in a statistically significant way. And yes, it does. The Tukey test established that there are three clusters of months within the eight that have essentially identical parasite infestations: a, which is low; b; which is medium; and c, which is high. These categories overlap, so that on the graph several months are presented as b, c and one month is a, b. But only one month, May, is unequivocally in the high infestation group, c. The big news here is that this pattern of infestation is very similar to the monthly pattern of gonadal maturation we found for this group of telescope shiners -- for whatever reason, gill fluke infestation peaks as reproductive potential peaks. We still have to finish analyzing whether there's a statistically significant relationship between relative gonad size (GSI) and gill fluke infestation. Andrew will hopefully have a fuller accounting of that later in the week.