Metamorphosis affects metal concentrations and isotopic signatures in a mayfly (Baetis tricaudatus): Implications for the aquatic-terrestrial transfer of metals

Environmental Science & Technology
By: , and 

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Abstract

Insect metamorphosis often results in substantial chemical changes that can alter contaminant concentrations and fractionate isotopes. We exposed larval mayflies (Baetis tricaudatus) and their food (periphyton) to an aqueous zinc gradient (3-340 µg Zn/l) and measured zinc concentrations at different stages of metamorphosis: larval, subimago, and imago. We also measured changes in stable isotopes (δ15N and δ13C) in unexposed mayflies. Larval zinc concentrations were positively related to aqueous zinc, increasing 9-fold across the exposure gradient. Adult zinc concentrations were also positively related to aqueous zinc, but were 7-fold lower than larvae. This relationship varied according to adult substage and sex. Tissue concentrations in female imagoes were not related to exposure concentrations, but the converse was true for all other stage-by-sex combinations. Metamorphosis also increased δ15N by ~0.8‰, but not δ13C. Thus, the main effects of metamorphosis on insect chemistry were large declines in zinc concentrations coupled with increased δ15N signatures. For zinc, this change was largely consistent across the aqueous exposure gradient. However, differences among sexes and stages suggest that caution is warranted when using nitrogen isotopes or metal concentrations measured in one insect stage (e.g. larvae) to assess risk to wildlife that feed on subsequent life stages (e.g. adults).

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Metamorphosis affects metal concentrations and isotopic signatures in a mayfly (Baetis tricaudatus): Implications for the aquatic-terrestrial transfer of metals
Series title Environmental Science & Technology
DOI 10.1021/acs.est.6b05471
Volume 51
Issue 4
Year Published 2017
Language English
Publisher American Chemical Society
Publisher location Easton, PA
Contributing office(s) Fort Collins Science Center
Description 9 p.
First page 2438
Last page 2446