Undercover footage showed a dolphin lying on its back in what appears to be an indoor pool.
A male zookeeper leans over the sea mammal and uses his glove hand to perform the sex act before feeding the dolphin a fish.
They also claimed there were “gay” dolphins at the zoo that have sex with each other in their tanks.
Leonie Vestering, leader of animal party Pvd D, pressed charges and accused the zoo of sexual abuse.
A zoo has been criticised after footage appeared to show a keeper performing a sex act on a dolphin .
But investigators say the act isn’t a crime because it was part of a “breeding programme”.
The zoo has claimed the weird act is to “de-stress” the animals.