HR: 09:45h
AN: NB41D-06    [Abstracts]
TI: Use of Relic Shells to Determine Time Since Mortality
AU: * Ashcraft, E A
EM: eashcraft@astate.edu
AF: Department of Biological Sciences, Arkansas State University, P.O. Box 599, State University, AR 72467 United States
AU: Farris, J L
EM: jlfarris@astate.edu
AF: Department of Biological Sciences, Arkansas State University, P.O. Box 599, State University, AR 72467 United States
AU: Farris, J L
EM: jlfarris@astate.edu
AF: Environmental Sciences Program, Arkansas State University, P.O. Box 847, State University, AR 72467 United States
AU: Walker, B L
EM: blwalker@astate.edu
AF: Department of Biological Sciences, Arkansas State University, P.O. Box 599, State University, AR 72467 United States
AU: Hannigan, R
EM: hannigan@astate.edu
AF: Environmental Sciences Program, Arkansas State University, P.O. Box 847, State University, AR 72467 United States
AB: As potential ecosystem impairment and/or degradation indicators, relic freshwater mussel valves may contain valuable information pertaining to life history, mortality, and taphonomy. Relic shells persist in aquatic systems long after mussel mortality and may be used to identify time passed since mortality. Such information may provide evidence in determinations of causality, responsibility, and reciprocity with applications that potentially extends beyond relics to modeling future populations or events. Using Unionids and surrogates, factors influencing decomposition rates for visceral mass, periostracum, nacre, hinge and overall valve condition were measured through both laboratory and field experimentations. Analysis of microbial communities associated with decomposing visceral mass provided short-term decomposition markers. X-Ray diffraction of nacre indicated calcium carbonate polymorph variations within and among different age and species. Digital microscopy with polarized light and geographic information system (GIS) mapping of thin-sections allowed percentage comparisons of aragonite and other calcium carbonate polymorphs and possible mineral replacements within shells. Selection of factors influencing decomposition and decomposition rate will enable measurable changes in shell integrity to be determined for the amount of time since mortality. Currently validation and consideration for decomposition rates incorporate both site and species-specific factors of relic shells whose time since mortality can be validated.
DE: 3699 General or miscellaneous
DE: 3954 X ray, neutron, and electron spectroscopy and diffraction
DE: 4840 Microbiology
DE: 9820 Techniques applicable in three or more fields
DE: 9902 NABS Student Award Applied Research
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly