A public aquarium in South Africa is trying to determine why the water it pumps into its tanks from the sea has become polluted with potentially dangerous ammonia.
According to a report by The Mercury, staff at the uShaka Marine World aquarium in Durban detected harmful ammonia in the intake water they suck up from the sea last year.
Mark Penning of uShaka told The Mercury that 0.l5 ppm of ammonia had been detected and was not likely to pose a threat to most fishes, but curator Mike de Maine was worried that the pollutant could cause problems for the aquarium's more sensitive inhabitants.
Francois Talbot, a marine chemist from the Department of Agriculture and Environmental Affairs has been brought in to investigate the cause of the water contamination.
According to the report, the aquarium draws in seawater from 60 wells located under a pier in front of the aquarium.
Rather than drawing in water directly from the sea, it is "filtered" by sucking it through 5m of beach sand.
The aquarium uses 600,000 litres of water per hour to run its aquaria which house around 8000 fish.
Many of the UK's public aquaria also utilise natural sea water for their aquariums.