Sperm Production and Larval Development in Hellbenders (Cryptobranchus Alleganiensis Alleganiensis And C. A. Bishopi): A Comparison of Declining and Stable Populations

Shem D. Unger

Date of Graduation

Summer 2003

Degree

Master of Science in Biology

Department

Biology

Committee Chair

Alicia Mathis

Abstract

The Ozark hellbender (Crytobranchus alleganiensis bishopi) has experienced severe population declines throughout its narrow geographic range. The eastern hellbender (C. a. alleganiensis), more widely distributed, is declining in some states but appears to be relatively stable in other areas. Previous studies estimate that populations of both subspecies in Missouri have declined 70-85%. This decline appears to be due at least in part to low recruitment. I compared sperm of declining Ozark and eastern hellbenders with that of males from healthy populations of eastern hellbenders. I also compared development of eggs and growth of larvae of declining and stable populations. There was no significant difference among populations in sperm motility, viability, and rate of forward progression. Sperm concentrations (sp/ml) were significantly lower in Missouri populations of both subspecies than in hellbenders from healthy populations in eastern states. There was no significant difference in development of eggs or growth of larvae among populations.

Subject Categories

Biology

Copyright

© Shem D. Unger

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