Parasite Infection Of Telescope Shiners Varies Seasonally

Students in my lab have been working this summer on a project that might seem like a white whale. They've been pulling the gills from the preserved telescope shiners that we collected monthly from February through September in 2007 from Hurricane Creek at the Walls of Jericho, and counting the number of gill flukes (Dactylogyrus spatulus) from each fish. We have ~30 fish from each month, so it's a reasonable data set. February through July are now finished, and it's shaping up as an interesting story. There's a rise in infestation from February (1.5 flukes per fish) to May (almost 6 flukes per fish), and then a decline in June and July. The numbers are significantly different at least between May on one hand, and February and July on the other. Check out the graph below, with error bars equal to one standard error.
We've heard anecdotally that parasite numbers in shiner-type fishes seemed to have a seasonal basis, but there's next to nothing in the literature about it. So once we finish the August and September collections we'll have the basis for a short article, demonstrating that at least telescope shiners show evidence of a seasonal variation in gill fluke numbers. I still have no good idea why this is, but it certainly needs more research.