Research

Collecting Minnows in August with Dr. Janovy at West Oak Creek, Lancaster County Nebraska and in the lab.

Collection Sites: The three sites chosen for this project include three converging streams located northwest of the city of Lincoln, in an agricultural region of the Salt Valley watershed of Lancaster County, Nebraska. Although the sites superficially resemble each other, stream and snail survey data reveal variation in biotic and abiotic factors between sites.

Collection sites: Elk Creek, West Oak Creek and Oak Creek in south eastern Nebraska

Study Organisms: The study focuses on parasites which belong to two different classes within the phylum Platyhelminthes; Monogenea and Trematoda, and which parasitize minnows (Cyprinidae).

Dactylogyrus (Cl. Monogenea) live on the gills of fish, are host specific, have direct life cycles (single fish host), and are bound by the movement of the fish host in the environment. Fish movement, and therefore monogene movement is restricted within a stream system by the extent to which stream flow is interrupted by natural or man-made barriers. As a result, the three Salt Valley Watershed collection sites are effectively isolated in so far as fish communities are isolated, and may be regarded as three distinct parasite communities.

Uvulifer (Cl. Trematoda) encyst under the skin of minnows, are generalist parasites, have multiple intermediate hosts in the lifecycle (ex. snail, fish and fish-eating bird), and may be carried great distances across the landscape by the bird definitive host. The infected birds release trematode eggs each time they defecate, though the trematode life cycle is completed only when the eggs land in streams where the second and third intermediate hosts are available. As a result the trematode communities are not isolated, but are limited by the availability of intermediate hosts at the different sites.

Due to variation in host specificity and complexity of life cycle among parasites, it is necessary to study a number of different parasites at locations which vary biotically and abiotically, in order to understand the ways in which habitat affect the ability of parasites to distribute themselves in nature. Quantification of this variation in stream site morphology is being conducted through measurements of flow rate, turbidity, temperature, width, depth, dissolved particles (electrical conductivity), and bacteria levels. The variation in sites has helped to rule out different factors determining parasite distribution in hosts.

In three years of research, data collection in the Salt Valley watershed has revealed interesting differences in the distribution of the parasites that live on the surface of minnows, including that congeneric parasite species (Dactylogyrus) exist in communities with site-specific structures. The work concentrated on three species of fish in this family is biologically meaningful, in that Pimephales promelas, Notropis stramineus and Semotilus atromaculatus and their respective parasitic worm communities are a system that can be used to reveal general principles by which parasite populations are maintained in nature. Such a small scale study, on the distribution of parasites in the environment, will answer questions of host specificity and relationships between parasites and their hosts spanning areas which vary abiotically.

Peruvian Amazon 2008

Alaine Kathryn Knipes, Ph.D.
Postdoctoral Research Associate: School of Biological Sciences at University of Nebraska- Lincoln,
AND Department of Biomedical Sciences: University of Zambia School of Medicine, P.O. Box 50110 Lusaka, Zambia.
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