Conservation genetics of two endangered unionid bivalve species: Epioblasma florentina walkeri and Epioblasma capsaeformis (Unionidae: Lampsilini)

Journal Molluscan Studies (Impact Factor: 1.5). 01/2002; 68:385-391.
  • [Show abstract] [Hide abstract]
    ABSTRACT: High concentrations of tetrodotoxin (TTX) have been detected in some New Zealand populations of Pleurobranchaea maculata (grey side-gilled sea slug). Within toxic populations there is significant variability in TTX concentrations among individuals, with up to 60-fold differences measured. This variability has led to challenges when conducting controlled laboratory experiments. The current method for assessing TTX concentrations within P. maculata is lethal, thus multiple individuals must be harvested at each sampling point to produce statistically meaningful data. In this study a method was developed for taking approximately 200 mg tissue biopsies using a TemnoEvolution® 18G × 11 cm Biopsy Needle inserted transversely into the foot. Correlation between the TTX concentrations in the biopsy sample and total TTX levels and in individual tissues were assessed. Six P. maculata were biopsied twice (nine days apart) and each individual was frozen immediately following the second sampling. Tetrodotoxin concentrations in biopsy samples and in the gonad, stomach, mantle and the remaining combined tissues and fluids were measured using liquid chromatography-mass spectrometry. Based on the proportional weight of the organs/tissues a total TTX concentration for each individual was calculated. There were strong correlations between biopsy TTX concentrations and the total (r(2) = 0.88), stomach (r(2) = 0.92) and gonad (r(2) = 0.83) TTX concentrations. This technique will enable more robust laboratory studies to be undertaken, thereby assisting in understanding TTX kinetics, ecological function and origin within P. maculata.
    Toxicon 08/2013; DOI:10.1016/j.toxicon.2013.07.024 · 2.58 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Non-lethal DNA sampling has long appealed to researchers studying population and conservation genetics, as it does not necessitate removing individuals permanently from their natural environment or destroying valuable samples. However, such an approach has not yet been well established in bivalves. In this study, we demonstrate that the gill represents a good source of tissue for non-lethal sampling in scallops. Removal of a few gill filaments caused no noticeable behavioral abnormalities or increased mortality rates in Zhikong scallop (Chlamys farreri) during a three-month period of observation. To facilitate rapid gill-based DNA extraction, six methods (MA-MF) were designed and evaluated, each requiring less than one hour of processing time. The optimal method was identified as MF, in terms of maintaining DNA integrity and genotyping accuracy. Further optimization of MF method by orthogonal experimental design suggested that the utilization of gills could be limited to 2 mg of sample, which is sufficient for performing up to 20,000 PCR reactions. We also demonstrate the excellent cross-species utility of MF in two additional scallop species, Yesso scallop (Patinopecten yessoensis) and bay scallop (Argopecten irradians). Taken together, our study provides a rapid and efficient approach for applying non-lethal DNA sampling in bivalve species, which would serve as a valuable tool for maintaining bivalve populations and conservation genetics, as well as in breeding studies.
    PLoS ONE 07/2013; 8(7):e68096. DOI:10.1371/journal.pone.0068096 · 3.53 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A new species and a new subspecies of Epioblasma are described from the Tennessee River drainage, USA. Epioblasma ahlstedti (Duck River Dartersnapper) currently is restricted to the Duck River in west-central Tennessee (TN). However, museum collections indicate that the species likely occurred in the Buffalo River, TN, a tributary to the Duck River, and in the Tennessee River at Muscle Shoals, Alabama (AL), and lower Shoal Creek, AL. The following diagnostic morphological characteristics of E. ahlstedti are based on the female: (1) pronounced posterior-ventral shell expansion of the adult female shell; (2) slate-gray to dark-purple mantle-pad; (3) spongy texture of the mantle-pad; and (4) display of a single, tan-colored micro-lure that moves slowly side-to-side. Epioblasma florentina aureola (Golden Riffleshell) currently is restricted to Indian Creek, a tributary to the upper Clinch River, Virginia. Historically , the species occurred in numerous tributaries in the Ten-nessee River drainage downstream at least to the Duck River. The following diagnostic morphological characteristics of E. florentina aureola are based on the female: (1) gray mantle-pad with a black mottled background; and (2) mantle-pad is pustuled but the pustules are rounded. The genus Epioblasma represents the most endangered group of freshwater mussels in North America; 18 of the recognized 25 species or subspecies are already extinct. Likewise, these newly described species and subspecies are critically endangered and despite being listed as endangered under the Endangered Species Act remain in need of focused conservation to prevent their extinction.


Available from
May 28, 2014