Date of Graduation

Fall 2002


Master of Science in Biology



Committee Chair

M. Chris Barnhart


Freshwater mussels have a unique life cycle in which they parasitize a fish host during their larval stage. While fish hosts of many mussel species have been identified, little is known of variation in host-specificity among populations, within species. I investigated host compatibility in two populations of the ellipse mussel in the Spring River and Gasconade River in southern Missouri. Preliminary tests confirmed that orangethroat and rainbow darters from the Gasconade River were suitable hosts for the Gasconade River ellipse mussel (38% and 43% transformation success, respectively). I then compared the suitability of orangethroat darters from the Gasconade and Spring River for mussels from both sites. I hypothesized that each mussel population would transform most effectively on the fish population with which it co-occurs. Although a few fish transformed large proportions of attached glochidia, average transformation success was very low (<5%) in all 4 of the population pairings. There were no significant differences in transformation success among these pairings. The poor transformation of Gasconade glochidia on Gasconade fish was inconsistent with the first experiment. Gasconade glochidia initially attached in significantly larger numbers than Spring River glochidia, and there were also differences in attachment success among individual mussels. Spring River glochidia also transformed poorly on Spring River orangethroat darters in a subsequent experiment at three different water temperatures. The available data indicate that the Gasconade ellipse can be compatible with orangethroat darters, but there is no such evidence for the Spring River ellipse. Further study is needed to test the hypothesis of population differences in host compatibility in this species.

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