Title page for ETD etd-12202004-233343

Type of Document Master's Thesis
Author Valenti, Theodore Walter
Author's Email Address tvalenti@vt.edu
URN etd-12202004-233343
Title Approaches for assessing toxicity of selected contaminants to freshwater mussels (Bivalvia: Unionidae)
Degree Master of Science
Department Biology
Advisory Committee
Advisor Name Title
Cherry, Donald S. Committee Chair
Currie, Rebecca J. Committee Member
Neves, Richard J. Committee Member
  • juveniles
  • toxicity
  • mercury
  • glochidia
  • freshwater mussel
  • chlorine
Date of Defense 2004-12-14
Availability unrestricted
Laboratory bioassays results suggest that early life stages of freshwater mussels are sensitivity to toxicants. However, toxicological databases for unionids are rather limited because standard test methods are yet developed, and no published studies report endpoints for chronic test that are > 9 days. The primary goals of my thesis research were to assess acute and chronic toxicities of chlorine and mercury to early life stages.

Inter- and intra-specific species variability in the tolerances of glochidia was observed during acute laboratory bioassays as endpoints were between 8 - 43 ppb for Hg tests, 1.0 - 2.5 ppm for NaCl tests, and 70 - 260 ppb for chlorine (TRC) tests. Glochidia of several species had equal or greater sensitivities to Hg and NaCl than test organisms commonly used to assess environmental risk (i.e.Ceridaphnia dubia, Daphnia magna, Pimephales promelas), whereas they were far more tolerant to TRC than many species.

Twenty-one day chronic test endpoints for juveniles were substantially lower than those calculated during acute bioassays with glochidia. Villosa iris 3-mo old juveniles were found to be quite sensitive to Hg as growth was significantly impaired at 8 ppb Hg. Chronic bioassays with TRC revealed a distinct decrease in susceptibility with increased aged for V. iris (relative sensitivities 3-mo > 6-mo > 12-mo), and that 2-mo old Epioblasma capsaeformis were more sensitive than comparable age classes of V. iris. However, both species were tolerant compared to other aquatic organisms, as the lowest endpoint was 20 ppb TRC.

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