Trace element accumulation in lotic dragonfly nymphs: Genus matters

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.

Comparing Trace Element Bioaccumulation and Depuration in Snails and Mayfly Nymphs at a Coal Ash–Contaminated Site

“…Although our study showed that concentrations of the coal ash–associated contaminants As and Se were higher in all the sample matrices including snails and mayflies at ash‐affected sites than at the reference sites, major remediation activities removed much of the spilled ash from the site in 2010 and 2011; and as a result, trace element concentrations in mayfly nymphs were shown to decrease in the 4 yr following the spill (Smith et al 2016). Overall, concentrations of trace elements associated with coal ash measured in mayfly nymphs in the present study remained similar to the ones reported in mayflies in other sites (Cid et al 2010; Opfer et al 2011; Fletcher et al 2014, 2017).…”

“…Although our study showed that concentrations of the coal ash-associated contaminants As and Se were higher in all the sample matrices including snails and mayflies at ash-affected 2: Biomagnification factors (BMFs) calculated as the ratio between the average concentrations of each trace element (expressed as parts per million dry wt) in the biota (i.e., mayfly nymphs and adult snails) and the average concentration of each trace element (expressed as parts per million dry wt) in their respective food resources (i.e., sediment and periphyton) a sites than at the reference sites, major remediation activities removed much of the spilled ash from the site in 2010 and 2011; and as a result, trace element concentrations in mayfly nymphs were shown to decrease in the 4 yr following the spill (Smith et al 2016). Overall, concentrations of trace elements associated with coal ash measured in mayfly nymphs in the present study remained similar to the ones reported in mayflies in other sites (Cid et al 2010;Opfer et al 2011;Fletcher et al 2014Fletcher et al , 2017. It is always complex to address the risks associated with trace elements on aquatic biota based solely on their concentrations because many factors can significantly affect trace element bioavailability and toxicity and, therefore, the consequences on the invertebrate populations (e.g., Mathews et al 2020).…”

Functional Feeding Groups of Aquatic Insects Influence Trace Element Accumulation: Findings for Filterers, Scrapers and Predators from the Po Basin

“…Aquatic invertebrates within closely related taxa, down to species in the same genus living in the same habitat, may well have very different body concentrations of trace metals [59,75]. For example, Fletcher et al [83] studied the trace element accumulations in eight genera of lotic dragonfly nymphs, revealing both a generic and intrageneric variation in accumulation patterns. Furthermore, the same authors found that the accumulations of some trace elements differed significantly among dragonflies that were different in body forms.…”

Contaminant characterization in wetland media surrounding a pulp mill industrial effluent treatment facility

“…During an earlier sampling event for a separate study, it was found that Odonata larvae were present in all wetlands in this study. Due to differences in body forms and habitat uses between Odonata families and genera (Fletcher et al 2017), the family Libellulidae was solely selected for sampling and were collected using a triangular dip net. Following sweeps through vegetated areas of wetlands, dip nets were emptied into a FieldmasterÒ 35 mesh, 500 lm sieve where Libellulidae of similar size (three to four cm length) were selectively removed.…”