Impact of an Undescribed Heterophyid Trematode on the Fountain Darter Etheostoma fonticola
Date
2000-05
Authors
Salmon, Melissa J.
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Abstract
An undescribed heterophyid trematode causes considerable pathogenicity in fountain darters Etheostoma fonticola collected from the Comal River, Texas Survivorship was monitored under refugium conditions and compared between wild fish collected from two sections of the Comal River, where the parasite is well established, and from two sections of the San Marcos River where it is not yet epizootic. Significantly lower survival was seen for fish collected from one section of the Comal River Wildinfected fish were challenged in a sealed-jar hypoxia test and no correlation was found between lethal dissolved oxygen (DO) values and parasite load. Also, five groups of labinfected fish were challenged in identical hypoxia tests at various times post-exposure to see if DO tolerance changes as time progressed after exposure The correlation for the lab-infected fish between decreasing mean lethal DO and increasing time post infection was significant, as well as the correlations between increasing parasite load and lethal DO for each group. Uninfected lab-reared fish were also tested in the sealed-jar hypoxia test in order to ascertain that the scattering of lethal DO values immediately after exposure was not due to handling stress The mean lethal DO of the infected fish was significantly higher than the mean lethal DO of the uninfected fish immediately after exposure. It was determined that this gill parasite does have an adverse affect on the fountain darter and that heavy parasite loads could impact the health of the fish.
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Keywords
etheostoma, trematoda, parasites
Citation
Salmon, M. J. (2000). Impact of an undescribed heterophyid trematode on the fountain darter Etheostoma fonticola (Unpublished thesis). Southwest Texas State University, San Marcos, Texas.