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Amphipods set to help toxicity testing of rivers, sediments

Hyalella azteca, a small amphipod commonly found in the aquatic system in North America, may provide the Environmental Protection Administration’s (EPA) National Institute of Environmental Analysis with a new level of sensitivity in its biotoxicity testing of rivers and sediments, the EPA said yesterday.

Amphipods are an order of animals that includes more than 7,000 described species of shrimp-like crustaceans.

The development was the result of a successful preliminary technical transfer from the US Geological Survey and the US Environmental Protection Agency to Taiwan, researcher Yang Hsi-nan (楊喜男) said.

ADVANTAGES

Before the hyalella, the institute had employed other live creatures — such as carp — as biotoxicity testers for toxins in river systems as well as treated water going into them, Yang said, adding that the hyalella offers many advantages that the other creatures do not.

“Because of its biological traits, the hyalella can provide a sensitivity to toxins that is up to 10 times that of carp,” Yang said.

This means that carp may detect toxic elements at 10 parts per million (ppm), but the hyalella can offer a positive test result for as low as 1ppm, he said.

Toxicity — usually pertaining to chemicals or metal residues — is usually measured in water and sediment in terms of “lethal concentration,” Yang said.

“For example, in acute biotoxicity tests, the lethal concentration is the concentration that kills half of the tested culture in a given amount of time [usually under 96 hours],” he said.

SENSITIVITY

The hyalella’s high sensitivity also means that test times can be shortened, Yang said, adding that the creature is cheap — the hyalella is about NT$100 per culture but carp are about NT$5,000 each.

Another advantage is that the hyalella can be used in the testing of 2,000 to 3,000 different types of toxins, Yang said.

So far, the institute had tested the crustacean in river water and sediment collected from Taipei’s Tamsui and Keelung rivers, Yang said, adding that after the initial testing is completed the creature would be applied to other river systems.
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