Species- and element-specific patterns of metal flux from contaminated wetlands versus metals shed with exuviae in emerging dragonflies

Dean E Fletcher; Angela H Lindell; Paul T Stankus; Christina M Fulghum; Erin A Spivey

doi:10.1016/j.envpol.2022.118976

Species- and element-specific patterns of metal flux from contaminated wetlands versus metals shed with exuviae in emerging dragonflies

Environ Pollut. 2022 May 1:300:118976. doi: 10.1016/j.envpol.2022.118976. Epub 2022 Feb 9.

Authors

Dean E Fletcher¹, Angela H Lindell², Paul T Stankus³, Christina M Fulghum⁴, Erin A Spivey⁵

Affiliations

¹ Savannah River Ecology Laboratory, University of Georgia, P. O. Drawer E, Aiken, SC, 29802, USA. Electronic address: fletcher@srel.uga.edu.
² Savannah River Ecology Laboratory, University of Georgia, P. O. Drawer E, Aiken, SC, 29802, USA. Electronic address: lindell@srel.uga.edu.
³ Savannah River Ecology Laboratory, University of Georgia, P. O. Drawer E, Aiken, SC, 29802, USA. Electronic address: stankus@srel.uga.edu.
⁴ Savannah River Ecology Laboratory, University of Georgia, P. O. Drawer E, Aiken, SC, 29802, USA. Electronic address: cfulghum@uga.edu.
⁵ Savannah River Ecology Laboratory, University of Georgia, P. O. Drawer E, Aiken, SC, 29802, USA. Electronic address: erin.spivey@uga.edu.

PMID: 35150795
DOI: 10.1016/j.envpol.2022.118976

Abstract

Dragonfly adults and their aquatic immature stages are important parts of food webs and provide a link between aquatic and terrestrial components. During emergence, contaminants can be exported into terrestrial food webs as immature adults fly away or be shed with their exuviae and remain in the wetland. Our previous work established metals accumulating in dragonfly nymphs throughout a contaminated constructed wetland designed to regulate pH and sequester trace metals from an industrial effluent line. Here, we evaluated the concentration and mass of metals leaving the wetland in flying emergents versus remaining in the wetland with the shed exuviae in 10 species of dragonflies belonging to 8 genera. Nine elements (Cu, Zn, Cd, Mn, V, Mg, Fe, Al, Pb) were evaluated that include essential and nonessential elements as well as trace and major metals. Metal concentrations in the emergent body and exuviae can differ by orders of magnitude. Aluminum, Fe, Mn, and Pb were largely shed in the exuviae. Vanadium and Cd were more variable among species but also tended to be shed with the exuviae. In contrast, Cu, Zn, and Mg showed a higher tendency to leave the wetland with an emerging dragonfly. Metals shed in dragonfly exuviae can moderate the transport of metals from contaminated wetlands. Taxonomic- and metal-specific variability in daily metal flux from the wetland depended upon concentration accumulated, individual body mass, and number of individuals emerging, with each factor's relative importance often differing among species. This illustrates the importance of evaluating the mass of metals in an individual and not only concentrations. Furthermore, differences in numbers of each species emerging will magnify differences in individual metal flux when calculating community metal flux. A better understanding of the variability of metal accumulation in nymphs/larvae and metal shedding during metamorphosis among both metals and species is needed.

Keywords: Aquatic insect; Aquatic-terrestrial linkages; Contamination; Dragonfly; Insect emergence; Metal.

MeSH terms

Animals
Environmental Monitoring
Metals
Metals, Heavy* / analysis
Odonata*
Trace Elements* / analysis
Water Pollutants, Chemical* / analysis
Wetlands

Substances

Metals
Metals, Heavy
Trace Elements
Water Pollutants, Chemical