Chironomidae (Midge) Sensitivities to Ammonia Using Multiple Endpoints in China and Australia for the Development of Water Quality Criteria for Freshwater River Systems in China

Abstract

Deriving water quality criteria (WQC) for aquatic risk assessment requires sufficient toxicity data, which can determine the accuracy of WQC. Given that toxicity data vary between test species and endpoints, there is a great need to compare such data to generate the most suitable data set for WQC derivation. In the present study, a series of 11 ammonia exposure bioassays were conducted on Chironomidae species in either China or Australia, with test species and test endpoints varied (2 Chironomus sp., enzymatic up to lethal endpoints, and no-observed-effect concentration up to median lethal concentration [LC50] as endpoint metrics). There were no statistically significant differences between toxicity results generated from China compared to Australia using Chironomus sp., indicating that published data on native species generated in different countries could be appropriate for inclusion in the development of local Chinese WQC. In addition, the Chironomidae larvae laboratory-based toxicity value (LC50 = 384.6 mg/L) was lower than that of the in situ field-based toxicity value (LC50 ≥ 451.2 mg/L) where sensitive life stages are used, and, specifically for C. riparius, endpoints linked to biochemical and gene expression effects could be as sensitive as or more sensitive than chronic endpoints, both of which were more sensitive than acute endpoints. These findings help in the development of WQC by demonstrating the suitability of inclusion of toxicity data from a range of sources, as well as adding to the overall pool of knowledge regarding sensitivity to ammonia which can be used in aquatic risk assessment.