Community structure and dynamics of Monogenea and Trematoda in three North American cyprinid species in the Salt Valley Watershed, Nebraska

The gill monogene communities of Pimephales promelas (fathead minnow) in 3 distinct sites on converging streams were investigated from 2004 to 2006 in 3 different seasons. Thirty collections of P. promelas were made in southeastern Nebraska along 3 converging tributaries: Elk Creek (40.88534 ̊N, 96.83366 ̊W), West Oak Creek (40.9082 ̊N, 96.81432 ̊W) and Oak Creek (40.91402 ̊N, 96.770583 ̊W), Lancaster County, Nebraska. In all, 103 P. promelas were collected from Elk Creek, 115 from West Oak Creek, and 78 from Oak Creek, and examined for gill monogenes. Among the P. promelas collected, 93.5% were infected with up to 3 species of Dactylogyrus including: D. simplex Mizelle, 1937; D. bychowskyi Mizelle, 1937; and D. pectenatus Mayes, 1977. Mean intensities at Elk Creek, West Oak Creek, and Oak Creek were 17.6, 22.8, and 25.1, and prevalences 88%, 95%, and 97%, respectively. At these 3 sites: (1) P. promelas is not sharing Dactylogyrus species with Semotilus atromaculatus (Creek chub) or Notropis stramineus (Sand shiner); (2) fish size and sex are not predictive of Dactylogyrus infection; (3) Dactylogyrus spp. vary (not always predictably) in their seasonal occurrence; (4) populations of Dactylogyrus spp. respond to environmental differences among sites; and (5) the community structure of Dactylogyrus spp. (order of abundance) is independent of environment.