Differences in dissolved cadmium and zinc uptake among stream insects: Mechanistic explanations

Environmental Science & Technology
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Abstract

This study examined the extent to which dissolved Cd and Zn uptake rates vary in several aquatic insect taxa commonly used as indicators of ecological health. We further attempted to explain the mechanisms underlying observed differences. By comparing dissolved Cd and Zn uptake rates in several aquatic insect species, we demonstrated that species vary widely in these processes. Dissolved uptake rates were not related to gross morphological features such as body size or gill size-features that influence water permeability and therefore have ionoregulatory importance. However, finer morphological features, specifically, the relative numbers of ionoregulatory cells (chloride cells), appeared to be related to dissolved metal uptake rates. This observation was supported by Michaelis-Menten type kinetics experiments, which showed that dissolved Cd uptake rates were driven by the numbers of Cd transporters and not by the affinities of those transporters to Cd. Calcium concentrations in exposure media similarly affected Cd and Zn uptake rates in the caddisfly Hydropsyche californica. Dissolved Cd and Zn uptake rates strongly co-varied among species, suggesting that these metals are transported by similar mechanisms.
Publication type Article
Publication Subtype Journal Article
Title Differences in dissolved cadmium and zinc uptake among stream insects: Mechanistic explanations
Series title Environmental Science & Technology
DOI 10.1021/es0404421
Volume 39
Issue 2
Year Published 2005
Language English
Publisher ACS
Contributing office(s) Toxic Substances Hydrology Program
Description 7 p.
First page 498
Last page 504
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