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Assessing Sperm Health of the Endangered Ozark Hellbender
Midwest Region, October 2, 2012
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Service Biologist Trisha Crabill mixes a dilution solution used to assess the concentration of sperm samples from Ozark hellbenders.
Service Biologist Trisha Crabill mixes a dilution solution used to assess the concentration of sperm samples from Ozark hellbenders. - Photo Credit: Jeffrey Briggler, Missouri Department of Conservation
Missouri Department of Conservation Biologist Dr. Jeffrey Briggler extracts sperm from an Ozark hellbender.
Missouri Department of Conservation Biologist Dr. Jeffrey Briggler extracts sperm from an Ozark hellbender. - Photo Credit: USFWS
Magnified dead (stained dark pink) and live (unstained) sperm cells of an Ozark hellbender. Membranes surrounding heads of dead sperm cells are permeable and absorb the stain, but live cells are impermeable to the stain.
Magnified dead (stained dark pink) and live (unstained) sperm cells of an Ozark hellbender. Membranes surrounding heads of dead sperm cells are permeable and absorb the stain, but live cells are impermeable to the stain. - Photo Credit: Jeffrey Briggler, Missouri Department of Conservation

Drastic declines have occurred in populations of the Ozark hellbender since the 1970s, and experts are still working to understand reasons for the salamander's decline.

 

One factor which has been identified as potentially contributing to declines, and in particular the reduced recruitment observed in the wild, is the sperm health of males. Endocrine disrupting compounds, which have been shown to alter normal reproductive development in various aquatic species, have been detected in streams occupied by Ozark hellbenders. Although concentrations of these compounds were lower than EPA standards to protect aquatic life, biologists have questioned if the presence of these or other undetected compounds, might be interfering with successful fertilization of eggs.

To address this question, Columbia Missouri Ecological Services Field Office is partnering with the Missouri Department of Conservation to assess the sperm health of wild Ozark hellbenders. Since 2010, Service biologist Trisha Crabill and MDC biologist Jeff Briggler have been capturing Ozark hellbenders during the breeding season and assessing rates of motility (percentage of moving cells), viability (percentage of live cells), and concentration of sperm samples.

The first year of assessments involved various modifications to techniques, as well as answering questions relevant to the Ozark hellbender captive propagation program at the Saint Louis Zoo, such as:

- How long can sperm samples be stored (unfrozen) before losing fertilizing potential?
- How quickly does the motility and viability of sperm cells diminish?
- What is the best way to activate sperm (i.e., trigger motility)?
- Is the quality of sperm consistent throughout the breeding season?
- What are the best combinations and concentrations extenders and cryoprotectants to cryopreserve hellbender sperm?

Assessments so far have focused primarily on males captured in the North Fork of the White River and the Eleven Point River. However, preliminary results indicate that Ozark hellbenders are producing healthy sperm, with viability and motility rates approaching 100 percent in some instances. In addition, males used in the breeding program at the Saint Louis Zoo have been assessed and also appear to have healthy sperm. Although exact causes behind Ozark hellbender declines continue to remain unclear, these results certainly bode well for captive breeding efforts and for natural reproduction in the wild.


Contact Info: Trisha Crabill, 573-234-2132 x 121, trisha_crabill@fws.gov



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