Toxicity of water and sediment from stormwater retarding basins to Hydra hexactinella
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Updated: Jan 25, 2026

Generation and Long-term Maintenance of Nerve-free Hydra
Published on: July 7, 2017
Rikke T Rosenkrantz1, Carmel A Pollino, Dayanthi Nugegoda
1Technical University of Denmark, Department of Environmental Engineering, Miljoevej, Building 113, DK-2800 Kgs. Lyngby, Denmark. rtr@env.dtu.dk
Abstract:
Hydra hexactinella was used to assess the toxicity of stormwater and sediment samples from three retarding basins in Melbourne, Australia, using an acute test, a sublethal test, and a pulse test. Stormwater from the Avoca St retarding basins resulted in a LC50 of 613 ml/L, NOEC and LOEC values of 50 ml/L and 100 ml/L, while the 7h pulse exposure caused a significant increase in the mean population growth rate compared to the control. Water samples from the two other retarding basins were found non-toxic to H. hexactinella. This is the first study to employ sediment tests with Hydra spp. on stormwater sediments and a lower population growth rate was observed for organisms exposed to sediment from the Avoca St retarding basins. The behavioral study showed that H. hexactinella tended to avoid the sediment-water interface when exposed to sediment from all retarding basins, compared to the reference sediment. Further work is needed to determine the long-term effects of stormwater polluted sediments and acute effects due to organism exposure to short-term high concentrations during rain events.
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