Date of Graduation

Summer 2002

Degree

Master of Science in Biology

Department

Biology

Committee Chair

M. Chris Barnhart

Abstract

The Neosho mucket is a freshwater bivalve that occurs in the upper Arkansas river system in SE Kansas, NE Oklahoma, NW Arkansas and SW Missouri. Timing of reproduction was compared at two sites in the Spring River system: Shoal Creek at Joplin, MO and Spring River at Carthage, MO. Monthly samples of 6-30 individuals were examined at each site in 2001 for the presence of brooded larvae. Females spawned in May and brooded eggs and larvae from May through July. This timing is atypical of Lampsilis species, which typically brood continuously from fall through summer. Gonad fluid was collected in the field and examined microscopically for occurrence of eggs or sperm. Observations of gametes in gonad fluid samples indicate that Neosho muckets undergo gametogenesis in the late summer and early fall. This pattern appears consistent with the primitive lampsiline pattern of fall spawning. At Shoal Creek, 90% of females reproduced in 2001, but only 40% of the females at Spring River did so. Sterilizing trematodes (Rhipidocotyle sp.) were observed in gonad samples from some individuals in both populations. These samples lacked gametes. Shell size differed significantly between the two populations. Mean lengths of Spring River and Shoal Creek shells were 96.4 and 71 mm, respectively. Growth curves derived from shell annuli were compared among ages, sexes, and sites. Size was consistently smaller at the same inferred age in Shoal Creek. Host acquisition of immunity to glochidia was tested by repeated infestations of largemouth bass. Transformation success decreased from 87% to 55% when bass were exposed twice in succession. Transformation success of a related species, L. cardium, on bass decreased from 68% to 23% after previous exposure Neosho mucket glochidia. These results demonstrate that immunity develops after infestation and extends to closely related species.

Subject Categories

Biology

Copyright

© Melissa Shiver

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