Premium
Cadmium accumulation and toxicity in the unicellular alga Pseudokirchneriella subcapitata : Influence of metal‐binding exudates and exposure time
Author(s) -
Paquet Nathalie,
Lavoie Michel,
Maloney Frédéric,
Duval Jérôme F.L.,
Campbell Peter G.C.,
Fortin Claude
Publication year - 2015
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1002/etc.2927
Subject(s) - cadmium , environmental chemistry , metal toxicity , toxicity , metal , heavy metals , chemistry , environmental science , toxicology , biology , organic chemistry
Predicting metal availability and toxicity for chronic (several hours or days) metal exposure scenarios, even for unicellular algae, is a major challenge to existing toxicity models. This is because several factors affecting metal uptake and toxicity, such as the release of metal‐binding exudates, changes in the kinetics of metal uptake and toxicity over time, and algal physiological acclimation to internalized metals, are still poorly understood. The present study assessed the influence of these factors on Cd uptake and toxicity in laboratory batch cultures of the freshwater alga Pseudokirchneriella subcapitata . To do so, changes in the free Cd 2+ concentrations caused by the release of metal‐binding algal exudates were monitored, 109 Cd accumulation in algal cells was measured, and Cd‐induced inhibition of algal growth as a function of exposure time (from 12 h to 96 h) was followed. Results indicate that metal‐binding exudates may decrease the proportion of the free Cd 2+ ion in solution up to 2‐fold, a decrease that affects Cd uptake and toxicity. Pseudokirchneriella subcapitata has the capacity to decrease net Cd uptake rate on short time scales (<24 h), but this reduction in the Cd uptake rate disappeared after 24 h, and Cd toxicity occurred at relatively high Cd concentrations in solution. These data illustrate some of the pitfalls of standard algal toxicity assays, which were designed for acute exposures, and suggest how robust chronic bioassays might be developed. Environ Toxicol Chem 2015;34:1524–1532. © 2015 SETAC