High sensitivity of the Antarctic rotifer Adineta editae to metals and ecological relevance in contaminated site risk assessments.

Anthropogenic activities in Antarctica have led to contamination of terrestrial sites, and soils in ice-free areas have elevated concentrations of metals, particularly around current and historic research stations. Effective management of Antarctic contaminated sites depends on the assessment of risks to a representative range of native terrestrial species. Bdelloid rotifers are an abundant and biodiverse component of Antarctic limno-terrestrial communities, and play a key role in nutrient cycling in Antarctic ecosystems. This study investigates the toxicity of 5 metals (cadmium, copper, nickel, lead and zinc) to the endemic bdelloid rotifer Adineta editae, both singly and in metal mixtures. Based on the concentrations tested, zinc was the most toxic metal to survival with a 7-d LC50 of 344 µg Zn/L, followed by cadmium with a 7-d LC50 of 1542 µg Cd/L. Rotifers showed high sensitivity using cryptobiosis (chemobiosis) as a sub-lethal behavioural endpoint. Chemobiosis was triggered in A. editae at low metal concentrations (e.g. 6 µg/L Pb) and is likely a protective mechanism and survival strategy to minimise exposure to stressful conditions. Lead and copper were most toxic to rotifer behaviour with 4-d EC50s of 18 and 27 µg/L, respectively, followed by zinc and cadmium (4-d EC50 values of 52 and 245 µg/L, respectively). The response of rotifers to the metal mixtures was antagonistic, with less toxicity observed than was predicted by the model developed from the single metal exposure data. This study provides evidence that this bdelloid rotifer represents a relatively sensitive microinvertebrate species to metals, and is recommended for use in contaminant risk assessments in Antarctica. This article is protected by copyright. All rights reserved. Environ Toxicol Chem 2023;00:0-0. © 2023 SETAC.