Parasite Community Structure in \u3ci\u3ePimephales promelas\u3c/i\u3e (Pisces: Cyprinidae) from Two Converging Streams

Parasites of the fathead minnow, Pimephales promelas, were examined in fish collected from Elk Creek (40.88534°N, 96.83366°W) and West Oak Creek (40.90821°N, 96.81432°W), Lancaster County, Nebraska. These two streams are part of the Salt Valley watershed and flow together approximately 2 km downstream from the collection sites to form Oak Creek. This study examined the extent to which the two tributaries constitute a continuous habitat with respect to fish hosts. The parasite community included Trichodina sp., Myxobolus sp., Dactylogyrus simplex, D. bychowskyi, and D. pectenatus (all on gills); Gyrodactylus hoffmani (gill and body surface); Posthodiplostomum sp. (neascus, body cavity); and Uvulifer ambloplitis (encysted in skin). Among 46 fish from Elk Creek and 56 fish from West Oak Creek taken on five dates during April-July 1998, U. ambloplitis was found in Elk Creek fish at prevalences of 44-100% but in only two West Oak fish on one date. Prevalence and mean abundance of D. simplex also differed between the two sites. On the basis of these observations, fish populations in the two streams were considered to be distinct, with little or no fish movement between the tributarie