Community Structure and Seasonal Dynamics of Dactylogyrus spp. (Monogenea) on the Fathead Minnow (Pimephales promelas) from the Salt Valley Watershed, Lancaster County, Nebraska

The gill monogene communities of Pimephales promelas (fathead minnow) in three distinct sites on converging streams were investigated from 2004 to 2006 in three different seasons. Thirty collections of P. promelas were made in southeastern Nebraska along three 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 three species of Dactylogyrus, including Dactylogyrus simplex Mizelle, 1937, Dactylogyrus bychowskyi Mizelle, 1937, and Dactylogyrus 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 three sites: (1) P. promelas does not share 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.

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

An investigation was made of the communities of gill monogene genus Dactylogyrus (Platyhelminthes, Monogenea) and the populations of blackspot parasite (Platyhelminthes, Trematoda) of Pimephales promelas, Notropis stramineus, and Semotilus atromaculatus in 3 distinct sites along the 3 converging tributaries in southeastern Nebraska from 2004 to 2006. This work constitutes the first multi-site, multi-year study of a complex community of Dactylogyrus spp. and their reproductive activities on native North American cyprinid species. The biological hypothesis that closely related species with direct lifecycles respond differently to shared environmental conditions was tested. It was revealed that in this system that, Cyprinid species do not share Dactylogyrus species, host size and sex are not predictive of infection, and Dactylogyrus community structure is stable, despite variation in seasonal occurrence and populations among sites. The biological hypothesis that closely related species have innate differences in reproductive activities that provide structure to their populations and influence their roles in the parasite community was tested. It was revealed that in this system, host size, sex, and collection site are not predictive of reproductive activities, that egg production is not always continuous and varies in duration among congeners, and that recruitment of larval Dactylogyrus is not continuous across parasites’ reproductive periods. Hatch timing and host availability, not reproductive timing, are the critical factors determining population dynamics of the gill monogenes in time and space. Lastly, the biological hypothesis that innate blackspot biology is responsible for parasite host-specificity, host recruitment strategies and parasite population structure was tested. Field collections revealed that for blackspot, host size, sex, and collection month and year are not predictive of infection, that parasite cysts survive winter, and that host movement is restricted among the 3 collection sites. Finally, experimental infections of hosts with cercaria isolated from 1st intermediate snail hosts reveal that cercarial biology, not environmental circumstances, are responsible for differences in infection among hosts.

Examining the use of terms "Conservation" "Restoration" and "Preservation" between Natural Resource Professionals and Literature Reviews

ABSTRACT This thesis will determine if there is a discrepancy between how literature defines conservation, preservation, and restoration, and how natural resource professionals define these terms. Interviews were conducted with six professionals from six different agencies that deal with natural resources. These agencies consisted of both government and non-government groups. In addition to interviewing these professionals regarding how they define the terms, they were asked where their work fits into the context of these terms. The interviewees’ responses were then compared with the literature to determine inconsistencies with the use of these terms in the literature and real world settings. The literature and the interviewees have agreed on the term conservation. There are some different points of view about preservation, some see it as ‘no management’ and some others see it as keeping things the same or ‘static.’ Restoration was the term where both the literature and professionals thought of moving an ecosystem from one point of succession or community, to another point on a continuum. The only thing in which they disagree on is the final goal of a restoration project. The literature would suggest restoring the ecosystem to a past historic condition, where the interviewees said to restore it to the best of their abilities and to a functioning ecosystem.