OREANDA-NEWS. May 2, 2012. The “summer shift” of crayfish has entered on duty at South-West Wastewater Treatment Plant. Australian red-clawed Cherax quadricarinatus will monitor the treated effluent quality. They replaced slender clawed crayfish, which feel more comfortable in cool water.

Scientists from St.-Petersburg Research Center for Ecological Safety of Russian Academy of Science, who have developed the biomonitoring system, replace “employees” at South-West Wastewater Treatment Plant (SWTP) twice a year: in late autumn and on the eve of summer.

As the warm weather comes the temperature of wastewater increases. If even in winter its temperature doesn’t fall below 16-18oC, in summer it becomes higher by 15-20oC.

In winter, native crayfish are used as animal bioindicators to monitor the composition of treated effluents at South-West Wastewater Treatment Plant. For them the optimal temperature should not exceed 22-23oC. In summer, Australian crayfish replace them – for these the comfortable temperature range is 18-31oC.

Watching the crayfish in the familiar environment will allow to avoid a false alarm system caused by the fact the animal feels discomfort due to water temperature.

Six crayfish monitor water state. This number of crayfish is necessary to get objective data. Only arthropods males work at the wastewater treatment plants. They are more stress-resistant and balanced.

Australian red clawed crayfish started to work at South-West Wastewater Treatment Plant in July 2011. In November, the scientists replaced these thermophilic crayfish with other slender clawed dwelling in the Neva. Now again “the summer shift” started to work.

To substitute the crayfish, the scientists take off a sensor from one animal to fix it to a similar tiny fastening glued to the carapace of the other. The slender clawed were taken to a laboratory where scientists will examine the animals and carry out an original “health check” by assessing their physiological status.