Chironomus riparius sediment toxicity testing based on the European Union's relevant sediment toxicity test protocol was carried out and its suitability was assessed. The sensitivity of Chironomus riparius was then compared to Hyalella azteca by evaluating two standard reference toxicants, Cd and fluoranthene A commonly used toxicological species, C. riparius, has been successfully acclimatized in the laboratory. The toxicological responses of reference toxicant KCl obtained by acute (48 h test) LC50 values for C. riparius ranged from 2.287 to 2.744 g/L, and the CV value was 6.9%. These results were highly reproducible. A pre-test determination of the health of H. azteca and C. riparius test specimens was consistent with the recommended CV values being below 50%. In metal and organic compound toxicity tests, the acute (96 h) LC50 values of Cd and fluoranthene for H. azteca were 6.26±0.28 μg/L and 35.39±2.03μg/L, respectively. The acute (48 h) LC50 values for C. riparius were 5.66±0.65 μg/L for Cd and 82.28±2.75 μg/L for fluoranthene. The TIE results for whole sediment showed that the main toxicants at sites HJ1, CGB, and CGC were PAH compounds due to significantly reduced toxicity after the addition of coconut charcoal. Porewater toxicity was significantly reduced after the addition of EDTA, showing that the main toxicant was trace metal at site CGA. Overall, TIE can be used to confirm that a causative toxicant has been correctly identified and quantitatively correlate its toxicity to the measured concentration. This study revealed that different (organic or inorganic) compounds showed specific toxicities in whole sediment and porewater toxicity tests; however, other confounding factors such as chemicals or organic carbons that change the dynamic equilibrium defy toxicity identification. Using benthic invertebrate organisms for evaluating guidelines for sediment quality showed that the sensitivity of the amphipods H. azteca and C. riparius to trace metals and organic compounds were sufficient to assess sediment quality. In the future, such benthic bioassay should be combined with chemical analysis to provide biological risk assessments that include bioavailability of toxicants of contaminated sediments for regulatory pratice

Amphipods, Chironomid, Sediment Quality Guidelines