Metamorphosis enhances the effects of metal exposure on the mayfly, Centroptilum triangulifer

Environmental Science & Technology
By: , and 

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Abstract

The response of larval aquatic insects to stressors such as metals is used to assess the ecological condition of streams worldwide. However, nearly all larval insects metamorphose from aquatic larvae to winged adults, and recent surveys indicate that adults may be a more sensitive indicator of stream metal toxicity than larvae. One hypothesis to explain this pattern is that insects exposed to elevated metal in their larval stages have a reduced ability to successfully complete metamorphosis. To test this hypothesis we exposed late-instar larvae of the mayfly, Centroptilum triangulifer, to an aqueous Zn gradient (32–476 μg/L) in the laboratory. After 6 days of exposure, when metamorphosis began, larval survival was unaffected by zinc. However, Zn reduced wingpad development at concentrations above 139 μg/L. In contrast, emergence of subimagos and imagos tended to decline with any increase in Zn. At Zn concentrations below 105 μg/L (hardness-adjusted aquatic life criterion), survival between the wingpad and subimago stages declined 5-fold across the Zn gradient. These results support the hypothesis that metamorphosis may be a survival bottleneck, particularly in contaminated streams. Thus, death during metamorphosis may be a key mechanism explaining how stream metal contamination can impact terrestrial communities by reducing aquatic insect emergence.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Metamorphosis enhances the effects of metal exposure on the mayfly, Centroptilum triangulifer
Series title Environmental Science & Technology
DOI 10.1021/es501914y
Volume 48
Issue 17
Year Published 2014
Language English
Publisher American Chemical Society
Contributing office(s) Fort Collins Science Center, Contaminant Biology Program
Description 8 p.
First page 10415
Last page 10422