Trace Element Distributions in Aquatic Insects: Variations among Genera, Elements, and Lakes

Abstract

The distribution patterns of trace element contaminants (As, Cd, Cu, Pb, Zn) among the tissues of freshwater insects (Chironomus, Clinotanypus, Procladius, Hexagenia, Sialis) are both taxon and element specific. In quantity terms (micrograms per animal), the gut is the major organ of Cd accumulation, while most of the As, Cu, Pb, and Zn accumulates in the body (i.e. animal minus gut and other organs). In concentration terms (micrograms per gram), Cd, Cu, and Zn are often highest in the gut, while Pb and As are not. Much of the As, and in some genera the Pb, appears to be bound externally. Respiratory and excretory structures generally contain small proportions of the total trace element burdens, except for Cu. Trace elements are not uniformly distributed along the gut but tend to accumulate either in the mesenteron (midgut) or in the proctodeum (hindgut), depending on the element and insect concerned. The distribution patterns of most of the trace elements vary little among populations of the mayfly Hexagenia from different lakes with the exception of Cd, for which the proportion of the total Cd burden localized in the gut increases markedly with increasing Cd concentrations in the whole nymph.

Arsenic accumulation, biotransformation and localisation in bertha armyworm moths

“…[33] Arsenate is additionally found, albeit at low levels, in the anterior foregut (Fig. 2h), a region that is relatively low in As III (SR) 3 .…”

Effects of acid‐volatile sulfide on zinc bioavailability and toxicity to benthic macroinvertebrates: A spiked‐sediment field experiment

“…Furthermore, zinc concentrations in chironomids generally did not show an increase with increasing sediment zinc (SEM zinc) concentration, suggesting either that zinc was not bioavailable, that chironomids were capable of actively regulating zinc concentrations in their tissues, or both. Since zinc is an essential element and since chironomids are capable of regulating zinc body burdens [38,39], both explanations seem probable. In addition, the mean zinc tissue concentrations recorded in this study (1.4-12.0 mol/g) are comparable to total chironomid tissue concentrations reported by other researchers.…”

Toxicity and Bioaccumulation of Cadmium in the Freshwater Bivalve Corbicula Fluminalis Müller, 1774.

“…More over it was found that concentrations of Cadmium were lower in shell than the corresponding values in soft tissue. This seems to be a common behavior for many aquatic organisms (Hare et al, 1991;Abdel Gawad, 2001& 2005, where the exoskeleton of contaminated organisms contains smaller amounts of trace metals relative to internal parts. …”