Trace element accumulation in lotic dragonfly nymphs: Genus matters

PLoS One. 2017 Feb 16;12(2):e0172016. doi: 10.1371/journal.pone.0172016. eCollection 2017.

Abstract

Constituents of coal combustion waste (CCW) expose aquatic organisms to complex mixtures of potentially toxic metals and metalloids. Multi-element trace element analyses were used to distinguish patterns of accumulation among 8 genera of dragonfly nymphs collected from two sites on a CCW contaminated coastal plain stream. Dragonfly nymphs are exceptional for comparing trace element accumulation in syntopic macroinvertebrates that are all predators within the same order (Odonata) and suborder (Anisoptera), but differ vastly in habitat use and body form. Sixteen trace element (Be, V, Cr, Ni, Cu, Zn, As, Se, Sr, Cd, Sb, Cs, Ba, Hg, Tl, and Pb) were analyzed and trophic position and basal carbon sources assessed with stable isotope analyses (C and N). Trophic positions varied within relatively narrow ranges. Size did not appear to influence trophic position. Trophic position rarely influenced trace element accumulation within genera and did not consistently correlate with accumulation among genera. Patterns between δ13C and trace element accumulation were generally driven by differences between sites. An increase in trace element accumulation was associated with a divergence of carbon sources between sites in two genera. Higher trace element concentrations tended to accumulate in nymphs from the upstream site, closer to contaminant sources. Influences of factors such as body form and habitat use appeared more influential on trace element accumulation than phylogeny for several elements (Ni, Ba, Sr, V, Be, Cd, and Cr) as higher concentrations accumulated in sprawler and the climber-sprawler genera, irrespective of family. In contrast, As and Se accumulated variably higher in burrowers, but accumulation in sprawlers differed between sites. Greater variation between genera than within genera suggests genus as an acceptable unit of comparison in dragonfly nymphs. Overall, taxonomic differences in trace element accumulation can be substantial, often exceeding variation between sites. Our results underscore the element and taxa specific nature of trace element accumulation, but we provide evidence of accumulation of some trace elements differing among dragonflies that differ in body form and utilize different sub-habitats within a stream reach.

MeSH terms

  • Animals
  • Environmental Monitoring / methods*
  • Heavy Metal Poisoning*
  • Nymph / drug effects
  • Nymph / metabolism*
  • Odonata / drug effects
  • Odonata / metabolism*
  • Poisoning*
  • Trace Elements / analysis
  • Trace Elements / metabolism*
  • Water Pollutants, Chemical / analysis*

Substances

  • Trace Elements
  • Water Pollutants, Chemical

Grants and funding

This material is based upon work supported by the Department of Energy and the Area Completion Projects group-Savannah River Nuclear Solutions under Award Number DE-EM0004391 to the University of Georgia Research Foundation. SAB of Area Completion Projects assisted with establishing the project goals and general study design of providing a detailed assessment of contaminant accumulation in biota of Beaver Dam Creek. This work has led to several publications on contaminant accumulations in this system. SAB is a trained fish ecologist with experience on the Savannah River Site where the study was conducted. The funding agency provided support in the form of salaries for authors [DEF, JVM, AHL, GKS] and research materials. The funding agency did not have an additional role in the detailed study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the 'author contributions' section. All final decisions on study design, data interpretation, and presentation in the submitted manuscript were made by DEF and JVM.