Potential effects of food addition to sediment on test conditions in sediment toxicity tests

Abstract

Purpose Standardized sediment toxicity assays often employ periodic additions of uncontaminated food to sustain energy and growth requirements of the test organisms. Consequently, selective feeding on this uncontaminated food may reduce exposure to sediment particles containing the test substance. To address this issue, some standard guidelines propose to add food to the sediment before spiking with the test substance to account for multiple exposure routes, including ingestion of contaminated food. The present study focused on the influence of different feeding regimens and compositions of the aqueous medium on water quality (ammonia concentrations) and test organism development. Materials and methods Lumbriculus variegatus, Hyalella azteca, and Chironomus riparius larvae were used as test organisms. Ammonia production was investigated under different feeding regimens and test conditions as well as under the presence of a potential inhibitor of nitrification, 4,4'-methylenedianiline. Results and discussion Ammonia concentrations strongly depended on the feeding regimen and on the type of food. An influence of 4,4'-methylenedianiline on test organisms or ammonia concentrations was not found at the tested level. Independently of ammonia concentrations, L. variegatus were more sensitive to food type and less sensitive to medium composition than H. azteca. Ammonia levels, emergence ratio, and development rate of C. riparius were not different under periodic feeding and single addition of Urtica. Findings suggest that in case of a "sediment-incorporated" feeding regimen, the time point of food addition to the sediment and careful pH control appear critical. For H. azteca and L. variegatus, an Urtica/cellulose mixture provides a balance between ammonia production and organism development. Conclusions This article gives recommendations and caveats for conducting spiked-sediment tests with a single addition of sediment-incorporated food. The presented work also contributed to the development of two recently adopted OECD test guidelines related to sediment toxicity and bioaccumulation testing with endobenthic oligochaetes.

Toxicity of fullerene (C60) to sediment‐dwelling invertebrate Chironomus riparius larvae

“…The mean head capsule length for the control larvae was 0.73 AE 0.09 mm and 0.66 AE 0.11 mm for the exposed organisms, a significant decrease ( p ¼ 0.0016, n ¼ 28, Mann-Whitney test). The highest ammonia concentration measured in the present study was in the exposure treatment in experiment 3 and was 6.2 mg/L, an amount much lower than 18 mg/L, which reportedly did not cause harmful effects on development or emergence of C. riparius [34]. 6C).…”

“…Ammonia (NH 4 þ), a compound that may cause toxic effects to organisms if present at high concentrations under alkaline conditions [34], was tested as a composite sample at the conclusions of the experiments, and the values were below those that would raise concerns about potentially harmful effects. Ammonia (NH 4 þ), a compound that may cause toxic effects to organisms if present at high concentrations under alkaline conditions [34], was tested as a composite sample at the conclusions of the experiments, and the values were below those that would raise concerns about potentially harmful effects.…”

Juvenile food limitation in standardized tests: a warning to ecotoxicologists

“…The influence of different food sources is mainly studied concerning the growth of animals, not only in eco(toxico)logical experiments (e.g., Ristola 1995; e.g., Egeler et al. 2010), but also in bioproduction for human consumption (e.g., Van Dam et al. 2002).…”

Fullerenes(nC60) affect the growth and development of the sediment-dwelling invertebrate Chironomus riparius larvae

“…The ammonium (NH 4 þ) content was measured from a composite sample at the end of the experiment. The ammonium content did not rise to a level (>18 mg/L) which could be harmful to a larva and its development (Egeler et al, 2010). The sediment pH was checked at the beginning and end of the experiments.…”