A researcher from the University of Kalyani, India, has found that plankton used as food on fish farms, live longer and produce more offspring if reared in diluted urine.
As part of their research, Bara Bihari Jana and his colleagues at the university, mixed ground water with human urine from the university's urinals and added the zooplankton Moina micrura, which is often fed to hatchling fish in commercial fisheries.
They also tried rearing the plankton in various cocktails of cow urine, vermin compost, poultry droppings and cow dung, all of which are commonly used in fish farming in regions where chemical fertilizers are not available.
All treatments used half a litre of urine, or half a kilo of dung, to every 4,500 litres of water.
Findings revealed that young plankton reared in human urine began reproducing at least four days earlier than those in other tanks. They also lived longer and produced more offspring.
According to the researchers human urine contains high concentrations of nitrogen compounds that degrade rapidly to release amino acids and minerals, fertilizing the growth of algae, which the plankton then feed on.
"We believe this quick release of nutrients induced the fast reproduction in the plankton," said Jana.
"We have not yet encountered any diseases or abnormalities in the zooplankton grown in tanks with human urine, but we are looking for hormone residues and antibiotics, just to be sure," he added.
The study appears in the journal Ecological Engineering, reports Nature.