Investigating the Adequacy of Selected Micro-Scale Bioassays to Predict the Toxic Potential of Freshwater Sediments through a Tier Process

Abstract

A battery of 20 bioassays was applied to assess test and endpoint performance in detecting the toxic potential of 15 freshwater sediment samples collected in the St. Lawrence River/Great Lakes systems. The bioassays included 18 micro-scale assays performed either on whole sediment, pore water or sediment organic extracts, as well as two standardized whole sediment bioassays undertaken with macroinvertebrates (Chironomus riparius and Hyalella azteca). Physical and chemical parameters of selected sediments were also analyzed to aid in the interpretation of results. Several qualitative and quantitative criteria were established for evaluating the reliability and usefulness of the micro-scale bioassays in predicting sediment toxicity based on a two-tier system. In Tier 1, micro-scale testing results were compared for general concordance with those of the benthic bioassays, benthic community structure index and with sediment contaminant levels. Micro-assays which complied with Tier 1 standards were further evaluated via a Tier 2 process consisting of selected (quantitative and qualitative) scientific and practical criteria. Of the 20 bioassays investigated, the two benthic assays and seven micro-scale assays successfully passed the double-tiered assessment. Micro-scale tests whose results most closely matched those of the benthic tests for appraisal of whole sediment toxicity, sediment contamination level and benthic community structure index included three bacterial assays (ATP assay, a micro-plate adaptation of the Microtox® assay, SOS Chromotest™), one algal assay (algal solid-phase test) and three micro-invertebrate assays (Thamnotoxkit™ F, Daphtoxkit™ F and Hydra assay). Two selected batteries, composed of the seven micro-scale assays and benthic invertebrate bioassays, are proposed for cost-effective appraisal of freshwater sediment toxicity.

A Review of the Microtox® Toxicity Test System for Assessing the Toxicity of Sediments and Soils

“…In a similarly ambitious study, Côté et al (1998) assembled a battery of 20 tests to assess the toxicity of 15 sediment samples collected from the St. Lawrence River and Great Lakes. In contrast to the study by Burton et al (1996), the majority of tests in this study were "microscale" tests.…”

Toxicity assessment of reference and natural freshwater sediments with the LuminoTox assay

“…A fairly large number of bioassays can be used to measure the toxicity of sediment elutriates, pore waters, and extracts, but fewer are presently available to evaluate that of whole sediment where both readily-soluble and adsorbed toxicants may be present (Côté et al, 1998). Recommended whole sediment toxicity tests are usually performed with benthic organisms that measure growth and survival after 10 or 14 days of exposure (Borgmann et al, 2005;Péry et al, 2005).…”

The SED‐TOX index: Toxicity‐directed management tool to assess and rank sediments based on their hazard—concept and application

“…Several exposure or test phases, such as pore water, elutriates, organic extract, wet sediment, and whole sediment, may also be examined. Numerous test batteries have been proposed for freshwater [4–6] and marine or estuarine [1,7,8] sediments. Given the wide range of possibilities in the choice of effect endpoints, receptors, and exposure phases, it is hardly surprising that combining toxicity results can be a very complex task.…”