Floating lab to save largest freshwater lake in Northeast

Thrice a week, five young girls take a back-breaking one and half hours of journey from Imphal to Loktak, Northeast India's biggest freshwater lake, located 54 km from Manipur's capital.

They run a floating laboratory on the nearly 300 sq km lake   - twice the size of the city of Mysore -   which has begun to throw up its first signs of degradation.

In some parts of the lake, the water turns acidic and in other parts, an increased volume of floating biomass islets begin to choke the gigantic water body.

Unless these problems are not nipped in the bud, the degeneration could spell an ecological disaster not only for the Northeast but for the famed Indo-Burma biodiversity hotspot as well.

"The lake has not gone to the ICU so far, but it is somewhere near," Dinabandhu Sahoo, director of the Institute of Bioresources and Sustainable Development, who leads the research effort on Loktak told DH sitting inside the floating laboratory on the lake.

The institute last month launched  a unique experimental station   - a motorboat that was converted into a data collection centre- to keep an eye on the lake's health.

IBSD researchers Sabeela Beevi, Kikku Kunui, Yambamree Nata, Rijeeba Haoba and Rajkumari Supriya collect data at 15 specific points.

Those spots were surveyed in 2001 and a fresh data set will illustrate the deterioration of the lake in the last two decades.

"Some of the parameters like temperature, electrical conductivity, dissolved oxygen and turbidity are analysed on the spot. For others like BOD (biological oxygen demand), COD (chemical oxygen demand), Fluoride, Phosphate and Nitrogen we take the samples to the IBSD," said Kikku, an IBSD senior research fellow.

The laboratory will function for at least one year to complete the data collection, on the basis of which an intervention can be designed.

Loktak is a unique ecosystem because of hundreds of floating islands of biomass -   locally called phumdi   -   that dots the picturesque lake.

With eutrophication, the biomass is growing rapidly beyond the carrying capacity of the lake  and shrinking the water body.

"It happens because untreated sewage from Imphal and surrounding areas is discharged directly. The huge inflow of nitrogen and phosphorus triggers a dense growth of plants (eutrophication) as the water becomes rich with nutrients favourable for plant growth," said Sahoo.

Excess nitrogen in the water adversely affects the indigenous fish species on which the livelihood of locals depends, whereas acidification harms numerous shellfish, mollusc and prawns. But in the absence of monitoring, the discharge continues.

With the floating laboratory in operation, IBSD now plans to set up a permanent station on one of the biomass islands (phumdi) with a data buoy that can automatically collect the data and transmit it throughout the year.